The BPMN 2. More information on deployment can be found in the dedicated section on deployment. As described in that section, deployment can happen in several ways. One way is through the API as follows. Note that all interaction with the Activiti engine happens through its services. Now we can start a new process instance using the id we defined in the process definition see process element in the XML file.
Note that this id in Activiti terminology is called the key. This will create a process instance that will first go through the start event. After the start event, it follows all the outgoing sequence flows only one in this case and the first task write monthly financial report is reached. The Activiti engine will now store a task in the persistent database. At this point, the user or group assignments attached to the task are resolved and also stored in the database. At such a wait state, the current state of the process instance is stored in the database. It remains in that state until a user decides to complete their task.
At that point, the engine will continue until it reaches a new wait state or the end of the process. When the engine reboots or crashes in the meantime, the state of the process is safe and well in the database. After the task is created, the startProcessInstanceByKey method will return since the user task activity is a wait state. In this case, the task is assigned to a group, which means that every member of the group is a candidate to perform the task.
We can now throw this all together and create a simple Java program. Create a new Eclipse project and add the Activiti JARs and dependencies to its classpath these can be found in the libs folder of the Activiti distribution. Before we can call the Activiti services, we must first construct a ProcessEngine that gives us access to the services. Here we use the 'standalone' configuration, which constructs a ProcessEngine that uses the database also used in the demo setup. You can download the process definition XML here.
This file contains the XML as shown above, but also contains the necessary BPMN diagram interchange information to visualize the process in the Activiti tools. We can now retrieve this task through the TaskService by adding the following logic:. Note that the user we pass to this operation needs to be a member of the accountancy group, since that was declared in the process definition:. We could also use the task query API to get the same results using the name of the group. We can now add the following logic to our code:. By default, no user is in the accountancy group.
Then click Users and add the group to fozzie. As explained, the process will execute up to the first user task. Select the Tasks page to view this new task. Note that even if the process was started by someone else, the task would still be visible as a candidate task to everyone in the accountancy group. An accountant now needs to claim the task. By claiming the task, the specific user will become the assignee of the task and the task will disappear from every task list of the other members of the accountancy group. Claiming a task is programmatically done as follows:.
In the Activiti UI App, clicking the claim button will call the same operation. The task will now move to the personal task list of the logged on user. You also see that the assignee of the task changed to the current logged in user. The accountant can now start working on the financial report. Once the report is finished, he can complete the task , which means that all work for that task is done.
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For the Activiti engine, this is an external signal that the process instance execution must be continued. The task itself is removed from the runtime data. The single outgoing transition out of the task is followed, moving the execution to the second task 'verification of the report'. The same mechanism as described for the first task will now be used to assign the second task, with the small difference that the task will be assigned to the management group.
In the demo setup, completing the task is done by clicking the complete button in the task list. The second task is now visible in the unassigned task lists. The verification task can be retrieved and claimed in exactly the same way as before. Completing this second task will move process execution to the end event, which finishes the process instance. The process instance and all related runtime execution data are removed from the datastore. When you log into Activiti Explorer you can verify this, since no records will be found in the table where the process executions are stored. Programmatically, you can also verify that the process is ended using the historyService.
Combine all the snippets from previous sections, and you should have something like this this code takes in account that you probably will have started a few process instances through the Activiti Explorer UI. As such, it always retrieves a list of tasks instead of one task, so it always works :. However, as you are going through the BPMN 2.
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This way, a manager could reject the financial report which would recreate the task for the accountant. Frameworks, and particularly open-source frameworks such as Activiti, can implement a solution that has the same and often better implemented ;- features as those of a big vendor. Due to the BPMN 2. The downside of a standard however, is the fact that it is always the result of many discussions and compromises between different companies and often visions. As a developer reading the BPMN 2. Since Activiti puts ease of development as a top-priority, we introduced something called the Activiti BPMN extensions.
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These extensions are new constructs or ways to simplify certain constructs that are not in the BPMN 2. Although the BPMN 2. The prerequisite of such a custom extension is that there always must be a simple transformation to the standard way of doing things. When using a custom extension, this is always clearly indicated by giving the new XML element, attribute, etc.
So whether you want to use a custom extension or not, is completely up to you. Several factors will influence this decision graphical editor usage, company policy, etc. We only provide them since we believe that some points in the standard can be done simpler or more efficient. Who knows, some day your idea might pop up in the specification! Events are used to model something that happens during the lifetime process.
Events are always visualized as a circle. In BPMN 2. Catching: when process execution arrives in the event, it will wait for a trigger to happen. The type of trigger is defined by the inner icon or the type declaration in the XML. Catching events are visually differentiated from a throwing event by the inner icon that is not filled i. Throwing: when process execution arrives in the event, a trigger is fired. Throwing events are visually differentiated from a catching event by the inner icon that is filled with black.
Event definitions define the semantics of an event. Without an event definition, an event "does nothing special". For instance a start event without and event definition does not specify what exactly starts the process. If we add an event definition to the start event like for instance a timer event definition we declare what "type" of event starts the process in the case of a timer event definition the fact that a certain point in time is reached.
Timer events are events which are triggered by defined timer. They can be used as start event , intermediate event or boundary event.
The behavior of the time event depends on the business calendar used. Every timer event has a default business calendar, but the business calendar can also be defined on the timer event definition. Where businessCalendarName points to business calendar in process engine configuration. When business calendar is omitted default business calendars are used. This format specifies fixed date in ISO format, when trigger will be fired. To specify how long the timer should run before it is fired, a timeDuration can be specified as sub-element of timerEventDefinition.
Example interval lasting 10 days :. Specifies repeating interval, which can be useful for starting process periodically, or for sending multiple reminders for overdue user task. Time cycle element can be in two formats. First is the format of recurring time duration, as specified by ISO standard. Example 3 repeating intervals, each lasting 10 hours :. When the endDate is reached the application will stop creating other jobs for this task.
Additionally, you can specify time cycle using cron expressions, example below shows trigger firing every 5 minutes, starting at full hour:. Please see this tutorial for using cron expressions. The recurring time duration is better suited for handling relative timers, which are calculated with respect to some particular point in time e. You can use expressions for the timer event definitions, by doing so you can influence the timer definition based on process variables.
The process variables must contain the ISO or cron for cycle type string for appropriate timer type. Note: timers are only fired when the job or async executor is enabled i. In fact, the two have nothing in common. BPMN error events are a way of modeling business exceptions.
Java exceptions are handled in their own specific way. Signal events are events which reference a named signal. A signal event definition is declared using the signalEventDefinition element. The attribute signalRef references a signal element declared as a child element of the definitions root element. The following is an excerpt of a process where a signal event is thrown and caught by intermediate events. The following methods on the org. RuntimeService can be used to throw a signal programmatically:. The difference between signalEventReceived String signalName ; and signalEventReceived String signalName, String executionId ; is that the first method throws the signal globally to all subscribed handlers broadcast semantics and the second method delivers the signal to a specific execution only.
We could then use the signalEventReceived String signalName, String executionId method to deliver the signal to these executions. By default, signals are broadcast process engine wide. This means that you can throw a signal event in a process instance, and other process instances with different process definitions can react on the occurrence of this event. However, sometimes it is wanted to react to a signal event only within the same process instance. A use case for example is a synchronization mechanism in the process instance, if two or more activities are mutually exclusive.
To restrict the scope of the signal event, add the non-BPMN 2. The following is an example of two separate processes communicating using signals. The first process is started if an insurance policy is updated or changed. After the changes have been reviewed by a human participant, a signal event is thrown, signaling that a policy has changed:. This event can now be caught by all process instances which are interested. The following is an example of a process subscribing to the event. Note: it is important to understand that a signal event is broadcast to all active handlers.
This means in the case of the example given above, that all instances of the process catching the signal would receive the event. In this case this is what we want. However, there are also situations where the broadcast behavior is unintended. Consider the following process:. The pattern described in the process above is not supported by BPMN. The idea is that the error thrown while performing the "do something" task is caught by the boundary error event and would be propagated to the parallel path of execution using the signal throw event and then interrupt the "do something in parallel" task.
So far Activiti would perform as expected. The signal would be propagated to the catching boundary event and interrupt the task. However, due to the broadcast semantics of the signal, it would also be propagated to all other process instances which have subscribed to the signal event. In this case, this might not be what we want. Note: the signal event does not perform any kind of correlation to a specific process instance. On the contrary, it is broadcast to all process instances. If you need to deliver a signal to a specific process instance only, perform correlation manually and use signalEventReceived String signalName, String executionId and the appropriate query mechanisms.
Activiti does have a way to fix this, by adding the scope attribute to the signal event and set it to processInstance. Message events are events which reference a named message. A message has a name and a payload. Unlike a signal, a message event is always directed at a single receiver. A message event definition is declared using the messageEventDefinition element. The attribute messageRef references a message element declared as a child element of the definitions root element.
The following is an excerpt of a process where two message events is declared and referenced by a start event and an intermediate catching message event. As an embeddable process engine, Activiti is not concerned with actually receiving a message. The reception of messages is therefore something you have to implement as part of the application or infrastructure into which the process engine is embedded. After you have received a message inside your application, you must decide what to do with it. If the message should trigger the start of a new process instance, choose between the following methods offered by the runtime service:.
If the message needs to be received by an existing process instance, you first have to correlate the message to a specific process instance see next section and then trigger the continuation of the waiting execution. The runtime service offers the following methods for triggering an execution based on a message event subscription:. In the case of a message start event, the message event subscription is associated with a particular process definition. Such message subscriptions can be queried using a ProcessDefinitionQuery :. Since there can only be one process definition for a specific message subscription, the query always returns zero or one results.
If a process definition is updated, only the newest version of the process definition has a subscription to the message event. In the case of an intermediate catch message event, the message event subscription is associated with a particular execution. Such message event subscriptions can be queried using a ExecutionQuery :.
Such queries are called correlation queries and usually require knowledge about the processes in this case that there will be at most one process instance for a given orderId. This is useful if the process needs alternative ways to react to different start events but eventually continues in a uniform way.
How It All Goes Down
A start event indicates where a process starts. The type of start event process starts on arrival of message, on specific time intervals, etc. In the XML representation, the type is given by the declaration of a sub-element.
Start events are always catching : conceptually the event is at any time waiting until a certain trigger happens. The authenticated user must be set with the method IdentityService. This code is baked into the Activiti Explorer application. So it works in combination with Forms. A none start event technically means that the trigger for starting the process instance is unspecified. This means that the engine cannot anticipate when the process instance must be started.
The XML representation of a none start event is the normal start event declaration, without any sub-element other start event types all have a sub-element declaring the type. More information can be found in the forms section Example:. A timer start event is used to create process instance at given time. It can be used both for processes which should start only once and for processes that should start in specific time intervals. Note: a start timer event is scheduled as soon as process is deployed.
Note: when a new version of a process with a start timer event is deployed, the job corresponding with the previous timer will be removed. The reasoning is that normally it is not wanted to keep automatically starting new process instances of this old version of the process. The XML representation of a timer start event is the normal start event declaration, with timer definition sub-element.
Please refer to timer definitions for configuration details. A message start event can be used to start a process instance using a named message. This effectively allows us to select the right start event from a set of alternative start events using the message name. When deploying a process definition with one or more message start events, the following considerations apply:.
The name of the message start event must be unique across a given process definition. A process definition must not have multiple message start events with the same name. Activiti throws an exception upon deployment of a process definition such that two or more message start events reference the same message of if two or more message start events reference messages with the same message name. The name of the message start event must be unique across all deployed process definitions.
Activiti throws an exception upon deployment of a process definition such that one or more message start events reference a message with the same name as a message start event already deployed by a different process definition.
Process versioning: Upon deployment of a new version of a process definition, the message subscriptions of the previous version are cancelled. This is also true for message events that are not present in the new version. When starting a process instance, a message start event can be triggered using the following methods on the RuntimeService :. The messageName is the name given in the name attribute of the message element referenced by the messageRef attribute of the messageEventDefinition.
The following considerations apply when starting a process instance:. Message start events are only supported on top-level processes. Message start events are not supported on embedded sub processes. If a process definition has multiple message start events, runtimeService. If a process definition has multiple message start events and a single none start event, runtimeService. If a process definition has multiple message start events and no none start event, runtimeService.
If a process definition has a single message start event, runtimeService. A message start event is visualized as a circle with a message event symbol. The symbol is unfilled, to visualize the catching receiving behavior. The XML representation of a message start event is the normal start event declaration with a messageEventDefinition child-element:. A signal start event can be used to start a process instance using a named signal. The signal can be fired from within a process instance using the intermediary signal throw event or through the API runtimeService. In both cases, all process definitions that have a signal start event with the same name will be started.
Note that in both cases, it is also possible to choose between a synchronous and asynchronous starting of the process instances. The signalName that must be passed in the API is the name given in the name attribute of the signal element referenced by the signalRef attribute of the signalEventDefinition. A signal start event is visualized as a circle with a signal event symbol. The XML representation of a signal start event is the normal start event declaration with a signalEventDefinition child-element:.
An error start event can be used to trigger an Event Sub-Process. An error start event cannot be used for starting a process instance. An error start event is visualized as a circle with an error event symbol. The XML representation of an error start event is the normal start event declaration with an errorEventDefinition child-element:.
An end event signifies the end of a path of a sub process. An end event is always throwing. This means that when process execution arrives in the end event, a result is thrown. The type of result is depicted by the inner black icon of the event. A none end event means that the result thrown when the event is reached is unspecified. As such, the engine will not do anything extra besides ending the current path of execution.
A none end event is visualized as a circle with a thick border with no inner icon no result type. The XML representation of a none end event is the normal end event declaration, without any sub-element other end event types all have a sub-element declaring the type. When process execution arrives in an error end event , the current path of execution is ended and an error is thrown. This error can caught by a matching intermediate boundary error event. In case no matching boundary error event is found, an exception will be thrown.
An error end event is visualized as a typical end event circle with thick border , with the error icon inside. The error icon is completely black, to indicate the throwing semantics. And error end event is represented as an end event, with an errorEventDefinition child element. The errorRef attribute can reference an error element that is defined outside the process:. The errorCode of the error will be used to find the matching catching boundary error event.
If the errorRef does not match any defined error , then the errorRef is used as a shortcut for the errorCode. This is an Activiti specific shortcut. More concretely, following snippets are equivalent in functionality. When a terminate end event is reached, the current process instance or sub-process will be terminated.
Conceptually, when an execution arrives in a terminate end event, the first scope process or sub-process will be determined and ended. Note that in BPMN 2. This rule applies in general: when for example there is a multi-instance call activity or embedded subprocess, only that instance will be ended, the other instances and the process instance are not affected. There is an optional attribute terminateAll that can be added. When true , regardless of the placement of the terminate end event in the process definition and regardless of being in a sub-process even nested , the root process instance will be terminated.
A cancel end event visualized as a typical end event circle with thick outline , with a full black circle inside. A terminate end event is represented as an end event, with a terminateEventDefinition child element. The cancel end event can only be used in combination with a bpmn transaction subprocess. When the cancel end event is reached, a cancel event is thrown which must be caught by a cancel boundary event. The cancel boundary event then cancels the transaction and triggers compensation. A cancel end event visualized as a typical end event circle with thick outline , with the cancel icon inside.
The cancel icon is completely black, to indicate the throwing semantics. A cancel end event is represented as an end event, with a cancelEventDefinition child element. Boundary events are catching events that are attached to an activity a boundary event can never be throwing.
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This means that while the activity is running, the event is listening for a certain type of trigger. When the event is caught , the activity is interrupted and the sequence flow going out of the event are followed. A reference to the activity to which the event is attached through the attachedToRef attribute. Note that a boundary event is defined on the same level as the activities to which they are attached i. See the specific boundary event types for more details.
A timer boundary event acts as a stopwatch and alarm clock. When an execution arrives in the activity where the boundary event is attached to, a timer is started. When the timer fires e. A timer boundary event is visualized as a typical boundary event i. A timer boundary event is defined as a regular boundary event. The specific type sub-element is in this case a timerEventDefinition element.
Please refer to timer event definition for details on timer configuration. In the graphical representation, the line of the circle is dotted as you can see in this example above:. A typical use case is sending an escalation email additionally but not interrupt the normal process flow.
Since BPMN 2. The interrupting is the default. The non-interrupting leads to the original activity is not interrupted but the activity stays there. Instead an additional executions is created and send over the outgoing transition of the event. In the XML representation, the cancelActivity attribute is set to false:. Note: boundary timer events are only fired when the job or async executor is enabled i. There is a known issue regarding concurrency when using boundary events of any type. Currently, it is not possible to have multiple outgoing sequence flow attached to a boundary event see issue ACT A solution to this problem is to use one outgoing sequence flow that goes to a parallel gateway.
An intermediate catching error on the boundary of an activity, or boundary error event for short, catches errors that are thrown within the scope of the activity on which it is defined. Defining a boundary error event makes most sense on an embedded subprocess , or a call activity , as a subprocess creates a scope for all activities inside the subprocess. Errors are thrown by error end events. Such an error will propagate its parent scopes upwards until a scope is found on which a boundary error event is defined that matches the error event definition.
When an error event is caught, the activity on which the boundary event is defined is destroyed, also destroying all current executions within e. Process execution continues following the outgoing sequence flow of the boundary event. A boundary error event is visualized as a typical intermediate event circle with smaller circle inside on the boundary, with the error icon inside.
The error icon is white, to indicate the catch semantics. As with the error end event , the errorRef references an error defined outside the process element:. If errorRef is omitted, the boundary error event will catch any error event , regardless of the errorCode of the error. In case an errorRef is provided and it references an existing error , the boundary event will only catch errors with the same error code. Following example process shows how an error end event can be used. When the 'Review profitability' user task is completed by stating that not enough information is provided, an error is thrown.
When this error is caught on the boundary of the subprocess, all active activities within the 'Review sales lead' subprocess are destroyed even if 'Review customer rating' was not yet completed , and the 'Provide additional details' user task is created. This process is shipped as example in the demo setup.
The process XML and unit test can be found in the org. An attached intermediate catching signal on the boundary of an activity, or boundary signal event for short, catches signals with the same signal name as the referenced signal definition. Note: contrary to other events like the boundary error event, a boundary signal event does not only catch signal events thrown from the scope it is attached to.
On the contrary, a signal event has global scope broadcast semantics meaning that the signal can be thrown from any place, even from a different process instance. Note: contrary to other events like an error event, a signal is not consumed if it is caught. If you have two active signal boundary events catching the same signal event, both boundary events are triggered, even if they are part of different process instances. A boundary signal event is visualized as a typical intermediate event Circle with smaller circle inside on the boundary, with the signal icon inside.
The signal icon is white unfilled , to indicate the catch semantics. An attached intermediate catching message on the boundary of an activity, or boundary message event for short, catches messages with the same message name as the referenced message definition. A boundary message event is visualized as a typical intermediate event Circle with smaller circle inside on the boundary, with the message icon inside.
The message icon is white unfilled , to indicate the catch semantics. Note that boundary message event can be both interrupting right hand side and non-interrupting left hand side. A boundary message event is defined as a typical boundary event :. An attached intermediate catching cancel on the boundary of a transaction subprocess, or boundary cancel event for short, is triggered when a transaction is cancelled.
When the cancel boundary event is triggered, it first interrupts all executions active in the current scope. Next, it starts compensation of all active compensation boundary events in the scope of the transaction. Compensation is performed synchronously, i. When compensation is completed, the transaction subprocess is left using the sequence flow s running out of the cancel boundary event. Note: Only a single cancel boundary event is allowed for a transaction subprocess. Note: If the transaction subprocess hosts nested subprocesses, compensation is only triggered for subprocesses that have completed successfully.
Note: If a cancel boundary event is placed on a transaction subprocess with multi instance characteristics, if one instance triggers cancellation, the boundary event cancels all instances. A cancel boundary event is visualized as a typical intermediate event Circle with smaller circle inside on the boundary, with the cancel icon inside.
The cancel icon is white unfilled , to indicate the catching semantics.
Since the cancel boundary event is always interrupting, the cancelActivity attribute is not required. An attached intermediate catching compensation on the boundary of an activity or compensation boundary event for short, can be used to attach a compensation handler to an activity. The compensation boundary event must reference a single compensation handler using a directed association. A compensation boundary event has a different activation policy from other boundary events. Other boundary events like for instance the signal boundary event are activated when the activity they are attached to is started.
When the activity is left, they are deactivated and the corresponding event subscription is cancelled. The compensation boundary event is different. The compensation boundary event is activated when the activity it is attached to completes successfully. At this point, the corresponding subscription to the compensation events is created. The subscription is removed either when a compensation event is triggered or when the corresponding process instance ends.
From this, it follows:. When compensation is triggered, the compensation handler associated with the compensation boundary event is invoked the same number of times the activity it is attached to completed successfully. If a compensation boundary event is attached to an activity with multiple instance characteristics, a compensation event subscription is created for each instance.
If a compensation boundary event is attached to an activity which is contained inside a loop, a compensation event subscription is created for each time the activity is executed. Note: the compensation boundary event is not supported on embedded subprocesses. A compensation boundary event is visualized as a typical intermediate event Circle with smaller circle inside on the boundary, with the compensation icon inside.
The compensation icon is white unfilled , to indicate the catching semantics. In addition to a compensation boundary event, the following figure shows a compensation handler associated with the boundary event using a unidirectional association:. A compensation boundary event is defined as a typical boundary event :. Since the compensation boundary event is activated after the activity has completed successfully, the cancelActivity attribute is not supported.
TimerEventDefinition , etc. See the specific catching event types for more details. A timer intermediate event acts as a stopwatch. When an execution arrives in catching event activity, a timer is started. A timer intermediate event is visualized as an intermediate catching event, with the timer icon on the inside. A timer intermediate event is defined as an intermediate catching event. An intermediate catching signal event catches signals with the same signal name as the referenced signal definition. An intermediate signal catch event is visualized as a typical intermediate event Circle with smaller circle inside , with the signal icon inside.
A signal intermediate event is defined as an intermediate catching event. The specific type sub-element is in this case a signalEventDefinition element. An intermediate catching message event catches messages with a specified name. The problem of misties, i. Oftentimes during the continuous use of a tying machine, peelings and chaff from the tie material -- whether the latter be cotton or synthetic twine, plastic tape, or other type material -- will build up behind the stringholder button to such an extent that the desired clamping action of the stringholder mechanism, and the resultant tensioning of the tie material, is greatly diminished.
This in turn will result in misties or even sometimes allow the clamped end of the tie material to completely fall out. The above-noted peeling buildup problem occurs primarily because the prior art stringholders are allowed to oscillate and pivot over, i. Thus, the prior art stringholder buttons can desirably cant over -- while clamping down forcefully against the associated tie material and the bearing face of the stringholder's support structure -- in the direction that the tie material assumes during the completion of the tying machine's wrapping cycle.
However, the button can also undesirably cant over in the direction the tie material assumes during the machine's knotting and pull out cycles and thereby effect excessive clamping forces tending to lock the tie material in place and thus to inhibit the last-mentioned cycles. This excessive clamping action also tends to strip off tie material filaments thereby causing chaff to build up which in turn increases the occurrence of misties, requires systematic stringholder clean up, and necessitates machine down time. For purposes of describing this invention, the specific tie material in question will be cotton twine.
However, it is to be understood that any of the above-noted types of tie materials can be utilized. Test experiments have shown that with prior art stringholders misties occur at the approximate rate of 1 mistie in every tying cycles. However, utilization of the present invention has achieved test results of only 1 mistie per several thousand tying cycles for smaller diameter twines. One specific test ran through approximately 38, tying cycles before a mistie occurred.
Additionally, it is to be noted that misties can occur from what is termed premature pull out, i. This problem is especially prevalent with the plastic tape type of tie materials. Such premature pull out can occur from either the above-noted chaff buildup with attendant diminished clamping power in the stringholder, or from the early severing and then partial pull out of the newly clamped twine end as the previously clamped twine end is properly dislodged by the action of the knife trap assembly; the latter action is discussed in detail later herein.
Another rather significant problem with prior art stringholder mechanisms is the fact that several different stringholder set-ups -- with different hand-filed configurations, surface finishes, and associated spring members -- were required to accommodate the various types, weights, and sizes of natural and synthetic tie materials being utilized by package tying machine users. In recent times, as many as thirty different stringholder mechanism set-ups were needed to handle the various tie materials. Utilization of the herein-disclosed invention, because of its advantageous ability to effectively clamp the twine in limited directions only, has dramatically reduced the requirement for different stringholders to some five basic set-ups.
There is provided in the present invention an improved twine catcher and knife trap assembly for a package tying machine. The improvement in the twine catcher resides in a slotted operating bearing or aperture in the support structure of the stringholder button that is so angled relative to oscillations of the stringholder button as to effect limited movement laterally of the button's shaft to the button.
Thus, the stringholder button can self-cam or cant over to a more forceful clamping position against the mating face of the support structure in a direction generally longitudinally of the slotted hole but is prevented from tilting in the direction generally normal thereto toward the machine's knotter mechanism.
Accordingly, the stringholder button is prevented from excessively clamping down and locking against the twine's original and second clamped end portions during that portion of a package tying operation wherein the knot is being formed and the original twine end is being pulled out from the twine catcher. Additionally, the cutter and pull out members of the machine's knife trap assembly are so positioned relative to one another as to delay the severing action until the pull out action is completed. That is, the pull out member first dislodges the original twine end before the cutter member severs the second twine end from the tied package thereby desirably releasing the tied package while maintaining a clamped hold on the previous second end as the new original end for the next consecutive cycle.
This stepwise procedure of pull out and severing assures that no premature pull out of the second twine end, whether complete or partial, will occur. This, in return, reduces the occurrence of misties and improves the machine's effectiveness. Thus, it is a principal object of this invention to provide an improved stringholder and knife trap assembly for a package tying machine which decreases the occurrence of misties in a package tying machine and thereby increases the machine's operational efficiency.
It is another object of this invention to provide an improved stringholder mechanism which allows maximal stringholder clamping action in limited desired directions. It is a further object of this invention to provide an improved knife trap assembly which decreases the possibility of premature pull out of the tie material by effecting stepwise pull out and severing operations. It is a still further object of this invention to provide an improved stringholder mechanism which can accommodate a much greater range of tie materials than heretofore possible.
The means by which the foregoing and other objects of the present invention are accomplished and the manner of their accomplishment will be readily understood from the following specification upon reference to the accompanying drawings, in which:. Having reference to the drawings, wherein like reference numerals indicate corresponding elements, there is shown in FIG. The assembly 20 is comprised of a stringholder mechanism and a cutter and pull out mechanism which are generally denoted by reference numerals 22, and 24, respectively. I slid to the edge and lowered my arm to the floor.
While I reached for the purse, I shoot a swift glance at the diner entrance as casually as if checking on the metal clock on the wall. But when I found nobody at the door, confusion hit me like a wet cloth. I glanced to Vassie again, as if asking for an explanation. She titled her head and rolled eyes to one side. He reached down, picked up my purse and handed it back to me. I heard about you last night.
The waitress came back with two large plates and settled them in front of us. I was too preoccupied with the unexpected episode with Lectyn. For the rest of the evening, I listened half-heartedly to Vassie chatting with excitement about an upcoming ball scheduled for the Freshmen next month. I drove home after dinner with way more scattered thoughts than I had gone out with. Late at night I was restless, tossing and turning as I struggled to fall asleep.
I kept imagining a butterfly trapped inside me and calling my name in different muffled voices. When I was awake again in the morning, I was exhausted. At breakfast Father asked if I had my things ready for school. You have school. Deep down I grew terrified at the question of how much more was locked up in my memory. I must have started high school two months ago but my recollection of it measured little to none.
When I received no objection to my reach for the car key, I quickly put on my sneaker and skirted out through the side door. I navigated the familiar streets, taking big gulps of air. As I slowly settled in, I began to think that I could really enjoy this newly acquired independence.
Despite having no recollection, I found an instant connection to the new school, when I rolled in with an influx of students. I walked down the busy hallway, rounded the corner to a row of orange lockers. I was grateful for an instant relief, when I spotted Vassie and Christy hanging out by one of lockers. Later when the bell rang, it cost me little effort to figure out where my classes were following a schedule that coincidentally was shared by all three of us.
By the time I was in the fifth period, I was totally at ease, embracing all the excitement of this new experience. Added to the thrill was finding Lectyn sitting right next to me in biology class.
Related Ch. 27 - Table For Two and Ch. 28 - The Time Catcher (The Warper)
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