JP2010240655A - Method for controlling press machine with motor load reducing function, and apparus for controlling press machine with motor load reducing function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an apparatus for controlling a press machine with a motor load reducing function, by which a press working is continuously conducted by reducing torque per one stroke as possible, thereby stabilizing the heat generation of the motor. <P>SOLUTION: Movements of a work shaft, a T shaft, and an A shaft, and completion of them are detected by providing a ram position calculating portion 31a, a starting point determining portion 31b, a timer value selecting and writing portion 31c, a ram shaft stopping portion 31e, and a stroke classification-motor startup standby time table for each starting point stored in a second storing means 32, in a CNC 30. When movements of the work shaft and the T shaft have been completed and the ram shaft is elevated and stopped, the starting point of the rum shaft at this time is determined (top dead center, second top dead center, rise end), the ram is stopped with a timer value in accordance with the stroke classification of the starting point, and subsequently the ram is moved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a press machine control method with a motor load reduction function, and more particularly to load reduction of a motor that drives a ram shaft.

  As an example of a press using a motion conversion mechanism for converting the rotational motion of the motor into the reciprocating motion of the ram, there is a press of the type that reciprocates the ram by rotating the screw mechanism forward and backward. As an example of a press in which the bell crank is reciprocally rotated by forward and reverse rotation of the screw mechanism and the ram is reciprocated (vertically moved) by the reciprocating rotation of the bell crank, a press as described in Patent Document 1 is used. There is.

  As shown in FIG. 10, the press described in Patent Document 1 has a configuration including a press machine main body 1 and a control device 2.

  The press machine main body 1 has a press machine 3, which is an example of a motion conversion mechanism that is rotated forward and backward by a motor 5 such as a servo motor mounted on a part 4 of a frame. A screw mechanism 7 is provided. One end of a first link 13 is pivotally connected to a ball nut 11 that is reciprocally engaged with the ball screw 9 in the screw mechanism 7. The other end of the first link 13 is pivotally connected to one end of a bell crank 17 that is pivotally supported by a bracket 15 provided in a part 4 of the frame.

  One end portion of the second link 19 is pivotally connected to the other end side of the bell crank 17, and the other end portion of the second link 19 reciprocates vertically in a guide portion 21 provided on the frame. It is pivotally connected to a ram 23 that is guided freely. A punch and a die (not shown) are located under the ram, and the punch and the die cooperate with each other to press the workpiece 24. The workpiece 24 is provided so as to be freely positioned at a machining position by a driving means (not shown).

  Since such a press machine is driven by a motor, by combining forward rotation and reverse rotation, the starting point and the descending end can be freely changed, and the speed can also be freely changed.

  As a feature of the motor control, since the output torque of the motor is larger in the low-speed rotation than in the high-speed rotation, it is necessary to process at a low speed in order to increase the applied pressure.

  Further, the motor torque varies depending on various factors such as the current value and the thickness and winding method of the coil winding. That is, during the acceleration / deceleration of the motor, the motor itself needs an acceleration torque for changing the rotation speed.

  Generally, when a torque for rotating a motor is generated, a current flows through the motor, but not all of the flowing current is used for rotational energy. Most of the surplus energy is converted to heat.

  Also, in general servo motors, when rotating below the specified ambient temperature and below the rated torque, the balance between the heat generation and heat dissipation becomes a temperature that does not destroy the motor function. It becomes.

  Furthermore, when designing a machine, the performance of the motor cannot be designed without considering the size, inertia, installation location, volume, cost, etc. of the motor. For this reason, as a result of comprehensive judgment, the acceleration torque in the selected motor is often higher than the rated torque.

  In other words, it is essential that the servo press be designed in consideration of motor heat generation in the process of determining machine performance.

  Conventionally, as a method of suppressing the heat generation of the motor of Patent Document 2, a temperature meter is installed in the motor to actually measure the heat generation amount, or the heat generation amount is estimated from conditions such as the material and the mold, and the temperature and the estimated value are determined. When a preset threshold value is exceeded, the effective value of the motor has been lowered by starting the cooling device to forcibly cool it or stopping the motor for a desired time.

JP 2001-9534 A JP 2001-150200 A

  However, in the case of conventional electric servo punch presses, it is a function to prevent abnormal temperature rise of the motor based on the assumption that the torque required for workpiece plastic processing is generated. In spite of an important relationship, there has been no direct measure for the relationship between the amount of heat generated by the motor and the acceleration torque.

  This is for the reason explained below.

  In general, when the machining load is not large and high-speed machining is emphasized with a short stroke, the phenomenon described later is noticeable.

  In the case of punching, the torque required for workpiece plastic processing is the torque that is applied instantaneously when the workpiece breaks. Therefore, if the energy per stroke unit time is calculated, the averaged effective torque is obtained. May never be high.

  In comparison, the energy per one stroke unit time occupied by the acceleration torque becomes long enough to require a high-speed rotation because of a long stroke, and it may never be ignored.

  That is, when press work with a longer stroke is continuously performed in the press machine, there is a problem that the motor generates heat and reaches an abnormal temperature even if the torque necessary for workpiece plasticity is negligible.

  FIG. 11 (a) shows the relationship between the speed pattern from the starting point to the descending end and the torque when the stroke is lengthened, and FIG. 11 (b) shows the relationship between the speed pattern and the torque with the short stroke. FIG. 11C shows the relationship between the speed pattern and the torque when the stroke is short, and FIG. 11D shows the relationship between the speed pattern and the torque with the shortest stroke.

  In these drawings, the hatched portion indicates the torque. That is, when the stroke is increased, the torque amount per one stroke unit time is increased. In other words, it is desirable to perform motor control of press working that can stabilize the heat generation of the motor and continuously perform the press work by reducing the torque amount per one stroke unit time as much as possible.

The present invention relates to a control method for a press machine that performs press working while performing movement control to lower or raise the ram shaft by a motor based on a machining program.
Storing the ram start-up waiting time in the storage means for each stroke length from the starting point of the ram to the descending end; and
Calculating the stroke length of the ram shaft that is controlled to move based on the machining program;
Extracting the ram start waiting time corresponding to the stroke length calculated in the previous step from the storage means;
Waiting for the movement control until the extracted activation waiting time elapses when the next ram is activated; and
The gist is that when the standby time has elapsed, the movement control of the ram shaft is continued to perform press working. Further, the present invention provides a control device for a press machine that performs press working while performing movement control for lowering or raising the ram shaft by a motor based on a machining program.
Storage means for storing the ram start-up waiting time corresponding to each stroke length from the starting point of the ram to the descending end;
Stroke length calculation means for calculating the stroke length of the ram shaft that is movement-controlled based on the machining program;
Extracting means for extracting from the storage means the ram start waiting time corresponding to the stroke length calculated by the stroke length calculating means;
Waiting means for waiting for the movement control until the extracted start waiting time elapses when starting the next ram;
The gist of the present invention is to have press means for continuing the movement control of the ram shaft when the standby time has elapsed.

  As described above, according to the present invention, the stroke of the ram based on the machining program is divided, the waiting time of the ram after punching is set for each of the divided strokes, and one stroke is obtained each time actual machining is performed. The starting point (top dead center, second top dead center, ascending end) of the ram position is determined every time, and after the punch is punched out with the waiting time of the divided stroke corresponding to the determined starting point, the ascending of the ram is stopped.

  For this reason, since the amount of torque per one stroke unit time becomes small, the heat generation of the motor can be stabilized and press working can be continuously performed.

It is a schematic block diagram of the press control apparatus with a motor load reduction function of this Embodiment. It is explanatory drawing explaining the relationship between the stroke of this Embodiment, and a timer value. It is a flowchart explaining the actual operation | movement of the press control apparatus with a motor load reduction function of this Embodiment. It is a flowchart explaining the actual operation | movement of the press control apparatus with a motor load reduction function of this Embodiment. It is explanatory drawing explaining calculation of a parameter. It is explanatory drawing explaining calculation of a stroke. It is a wave form diagram explaining the speed waveform and positioning timing of each axis. It is explanatory drawing explaining the ram position waveform when the waiting time (timer value) of this Embodiment is put. It is explanatory drawing explaining the effect by putting the waiting time of this Embodiment. It is a schematic block diagram of the conventional press. It is explanatory drawing for demonstrating a subject.

  The present embodiment is a press machine control device with a motor load reduction function that regulates the maximum hit rate according to the ram stroke in order to keep the load of the motor of the press machine below a certain range.

  When pressing from a short stroke to a long stroke, that is, when pressing is performed on the ram shaft with different acceleration / deceleration times of the motor, the required energy per unit time differs, so the amount of heat generated by the motor differs.

  Therefore, in order to stabilize the heat generation amount of the motor according to the stroke amount and continuously perform the press work without causing the motor to become abnormal temperature, the starting point (top dead center, second top dead center, rising end) is determined from the press pattern information. ) And the descending end, and the stroke amount is determined based on this result.

  Then, the stroke amount is classified into preset divisions, and a timer value corresponding to the division is calculated from the punch completion point.

  Next, after waiting for the timer value to expire, the next punch is activated.

  That is, the timer value corresponding to the ram stroke (the shortest time from when the ram axis passes the punch completion point to the start of the next ram axis operation) is set so that the motor load factor (effective torque) does not exceed 100%. Set to reduce motor load.

  The essence of this case is that the timer value is changed in order to level the effective torque of the ram shaft, and not only the ram shaft but also the moving distance of the workpiece is implicitly involved. In other words, the following cases are assumed.

  For example, when the stroke is short, such as marking, the effective torque is originally small and the amount of movement of the workpiece at that time is also small, so the timer value may be short.

  On the other hand, when the stroke is longer than the marking such as a thin plate punch, the timer value is set larger than the marking.

  Also, a longer stroke such as a medium-thick plate punch tends to increase the amount of movement of the workpiece, so the timer value is increased.

  Furthermore, since a workpiece having a longer stroke, such as a thick plate punch, tends to increase the amount of movement of the workpiece, the timer value is further increased.

  In other words, in the present embodiment, the machining requiring force tends to increase the ram stroke and the amount of movement of the workpiece. Therefore, the stop time when the ram rises after the die (also called punch) is punched To reduce the effective torque.

<Embodiment>
FIG. 1 is a schematic configuration diagram of a press machine control device with a motor load reduction function according to the present embodiment. In addition, description is abbreviate | omitted to what has attached | subjected the code | symbol similar to FIG. The motor 5 is connected to an encoder 5E (which conventionally has an encoder). The encoder 5E detects the rotational speed of the rotating shaft of the motor 5. The motor 5 is connected to a ball screw 9 of the screw mechanism 7, and the ball screw 9 is connected to a ram 17.

  On the other hand, the CNC 30 (control device) of the present embodiment is provided with each part described below to regulate the maximum hit rate according to the ram stroke in order to keep the motor load within a certain range.

  As shown in FIG. 1, the CNC 30 includes a ram axis control software unit 31, first storage means 33 that stores tool parameters, press patterns, machine parameters, and the like, and timer values (ram axis) for each starting point. Is stored in the second storage means 32, the workpiece movement software unit 34, the tool selection software unit 35, and various parameters and stroke timers. An information setting unit 36 for setting a value is provided.

  Each parameter stored in the first storage means 33 will be specifically described below. The tool parameter stores the length of the punch corresponding to each tool number (TXXX) used in the punch press. The press pattern stores a press ram stroke pattern corresponding to each press pattern number (MOO), and more specifically, set values of positions such as the rising end, falling end, and die upper surface of the ram. FIG. 2 shows machine parameters, in which timer values corresponding to the stroke length of the ram are set and stored. Further, top dead center position information and second top dead center position information are also set and stored as machine parameters.

  The ram axis control software unit 31 includes a ram position calculation unit 31a, a start point determination unit 31b, a timer value selection / write unit 31c, a ram axis start standby unit 31e, and the like, and the current start point (top dead center) of the ram axis. Point, second top dead center, ascending end), and after setting the time to wait for the start of the next ram operation with the timer value corresponding to the stroke classification of the starting point, the ram is moved.

  That is, immediately after the tool is selected, the timer value starts at the top dead center at the timing when the workpiece movement is completed before the die contacts the workpiece, that is, immediately before the workpiece movement is completed so as to synchronize with the completion of the workpiece movement. Is set to start the ram, and then the timer is started at the punch completion point at which the mold is detached from the work, and the next work movement is started. The next ram activation is after the waiting time of the timer has elapsed and immediately before completion of the workpiece movement. Also, immediately before the start of the ram, the starting point of the current ram (top dead center, second top dead center, rising edge) is determined, and the appropriate timer value is set as the time to wait for the start of the next ram operation based on the stroke length. Set.

  Therefore, the workpiece movement software unit 34 controls the movement of the workpiece based on the machining program, and notifies the ram axis control software unit 31 of the workpiece movement start or movement completion.

  The tool selection software unit 35 controls the tool selection based on the machining program, and notifies the ram axis control software unit 31 of the start or completion of movement of the tool selection.

  The ram position calculation unit 31a detects the position of the ram shaft based on the pulse signal from the encoder 5E.

  The start point determination unit 31b determines the current position of the ram axis (A axis) when the conditions of the ram axis start condition (after the timer standby time has elapsed and immediately before the completion of the work table movement) are met. Whether it is the starting point (top dead center, second top dead center, or rising end) is determined from the machine parameter of the first storage means 33, and the determination result is notified to the timer value selection / writing unit 31c.

  When the timer value selecting / writing unit 31c classifies the stroke from the starting point (top dead center, second top dead center, or rising end) from the starting point determination unit 31b, the timer value corresponding to the classification (also referred to as waiting time). ) Is extracted from the stroke classification-start waiting time table of the second storage means 32, and the timer value of the corresponding starting point is selected.

  The ram axis activation standby unit 31e sets the selected timer value as a use timer (CNC parameter timer in FIG. 1), and waits for activation of the motor 5 (ram) until this timer value at the next punch activation.

  The information setting unit 36 stores a stroke classification-motor activation standby time table obtained by a simulation apparatus to be described later in the second storage unit 32, while storing machine parameters, a press pattern, and the like in the first storage unit 33. .

  The press machine control apparatus with a motor load reduction function configured as described above will be described below.

  First, a description will be given of a simulation apparatus which is a setting operation of the stroke classification-motor activation standby time table stored in the second storage means 32 in FIG. The setting operation of the stroke classification-motor activation standby time table is performed by a simulation device (not shown). Of course, the function of the simulation apparatus may be provided in the CNC 30.

  First, in the present embodiment, the information setting unit 36 registers initial settings of machine parameters, tool parameters, and press pattern parameters in advance.

  Next, the stroke classification / motor activation standby time table creation unit 40 reads the machining program 41 and reads the press pattern number (M500), the tool number (T201), etc. written in the machining program 41. Then, the press pattern parameter 43 corresponding to the press pattern number is extracted, the rising end, the die upper surface, the falling end, etc. are read, and the die length, punch length, etc. of the tool parameter 42 corresponding to the tool number are read.

  Based on these data, the distance (RB) from the rising end to the falling end, which is the length of each stroke, is calculated, the distance (RA) from the second top dead center to the falling end, and the falling end from the top dead center. Is calculated (see FIG. 6). Then, the top dead center, the second top dead center, and the stroke length of the rising end (RC) from the timer value corresponding to the stroke length of the ram shown in FIG. , RB, RA) An appropriate timer corresponding to the selected timer is selected and stored in the second storage means 32 of the stroke classification / motor activation standby time table as a timer table for each starting point.

  Then, immediately before the start of the ram, which is the actual machining based on the machining program, the top dead center, the second top dead center, or the rising end of the current ram is determined, and the stroke classification-motor start standby time table An appropriate timer value corresponding to any one of the top dead center, the second top dead center, and the rising end, which is the starting point stored in the second storage means 32, is set as a time for waiting for the start of the next ram operation. After the ram is started and the ram is waited for the set timer value after passing through the punch completion position, when the ram is started at the next machining position, the top dead center and the second top dead center are similarly set. A timer corresponding to either the point or the rising edge is set. It is repeated in the same way for each subsequent ram activation.

  Further, when the machining by the machining program 41 progresses and the press pattern number or the tool number is changed, the setting operation of the stroke classification-motor activation standby time table is again performed by the above-described simulation apparatus, and a new operation corresponding to the stroke is performed. The timer value is stored in the second storage means 32.

  Next, the timer value determination process according to the ram stroke length shown in FIG. 2 which is a machine parameter set in advance before actual machining by the machining program will be further described.

For each stroke length, try applying it while gradually increasing the startup standby time (timer value), and the effective value (effective torque) that does not exceed the rated effective value of the motor torque and can have a constant torque Is calculated. By repeating this, a timer value table corresponding to the stroke as shown in FIG. 2 is set.

The effective value is calculated by the following formula. Effective torque is obtained by multiplying the square of acceleration torque by the required time, multiplying the square of constant speed torque by the required time, multiplying the square of deceleration torque by the required time, and adding these three. It is divided by the total required time and the value is multiplied by 1/2. Note that the total required time here refers to the hit rate, so the time when the ram is not operating, for example, the time when the ram operation is waiting until the workpiece movement is completed (denoted as waiting time in the following formula) The cycle time including

  FIG. 9 is a graph showing the effective torque corresponding to each stroke obtained by the above calculation formula for a predetermined press pattern. In the graph described as “prior art” indicated by Δ, the rated torque may be exceeded when the stroke becomes long when the start standby time (timer value) is not set to “0”. On the other hand, since the present invention in which the start standby time (timer value) is set according to the stroke length is calculated to be less than the rated torque, the ram effective torque is as shown in the graph. become. Therefore, when actual machining is performed with the start-up waiting time (timer value) set here, the effective torque decreases as the stroke length increases, and the motor continues even when machining is performed continuously. Temperature rise can be suppressed.

  Next, actual processing will be described.

  After the setting process (S1) of the stroke classification-motor activation standby time table stored in the second storage means 32 described above with reference to FIG. 3 is completed, the ram axis control software unit 31, the workpiece movement software unit 34, and The tool selection software unit 35 reads a machining program (S2).

  Next, the starting point determination unit 31b of the ram axis control software 31 determines whether or not the tool selection is completed and the workpiece movement is completed (S3).

  Next, the starting point determination unit 31b determines whether or not the ram axis movement has been completed (whether any starting point has been reached) (S4). If it is determined in step S4 that the ram axis movement has been completed, the starting point of the ram axis is determined (S5). That is, it is determined whether the ram is at the top dead center, the second top dead center, or the rising end.

  Then, a timer value corresponding to the determined starting point is selected from the stroke category-motor activation standby time table stored in the second storage means 32 (S6).

  In this process, the starting point determination unit 31b refers to the signal information from the machine and servo from the ram position calculation unit 31a and the machine parameter data in the first storage unit 33, so that the ram has a top dead center, a second top dead center, Determine one of the rising edges.

  Then, based on the determination result, the timer value selecting / writing unit 31c performs the maximum hit rate restriction timer value determining process, and sets the determined timer value in the timer of the ram axis activation standby unit 31e.

  Next, the ram shaft activation standby unit 31e confirms whether or not the T-axis positioning is completed as shown in FIG. 4 from the signal of the ram position calculation unit 31a (S8: refer to FIG. 7).

  Next, it is determined whether or not the workpiece positioning is completed (S9). If it is determined in step S9 that the workpiece positioning has been completed, it is determined whether or not the ram has further lowered (S10).

  If it is determined in step S10 that the ram has further lowered, it is determined whether or not the ram has been raised after punching the die (S11).

  If it is determined in step S9 that the workpiece positioning is not completed, the process returns to step S9.

  If it is determined in step S11 that the ram has risen, it is determined whether or not the punch completion position has been passed (S13). If it is determined that the vehicle has passed, the timer for the shortest time until the start of the next ram axis start is started, and the ram axis further moves up and moves to the set end point (ascending end, second top dead center, top dead center) and rises. Stop.

  Then, the ram is made to wait until the start of the ram axis starting after the set timer time (S14).

  Next, it is determined whether or not the processing is finished (S15). When it is determined that the processing is finished, the ram ascent is stopped (S16), and it is determined whether or not the processing is finished (S17). If not, the process returns to step S5.

  That is, the ram shaft start standby unit 31e waits for the start (lowering start) of the next ram shaft for a time based on the timer value after the ram shaft passes the punch completion point. Specifically, as shown in FIG. 8, even if the next ram axis activation is a command indicated by ×, the ram movement (down) start is indicated as indicated by ○ after waiting for a time based on the timer value. Will be delayed.

  The start waiting time (timer time) to be set has been described as the timer time starting from the punch completion point. However, after the ram has stopped rising from the top dead center, the second top dead center, or the rising end, It may be set as a timer time.

  In addition, the timer value during the ram machining by the machining program is selected from the top dead center, second top dead center, and rise starting from the timer value in the stroke classification-motor activation standby time table stored in the second storage means 32. The method of selecting by one of the ends has been described, but the stroke length of the next ram activation is obtained without using the stroke classification-motor activation standby time table stored in the second storage means 32, and the stroke of FIG. The timer value may be selected directly from the stroke length obtained using the length and timer value table.

5 Motor 5E Encoder 7 Screw mechanism 9 Ball screw 17 Ram 31 Ram axis control software part 34 Work movement software part 35 T axis movement software part

Claims (6)

In a control method of a press machine that performs press processing while performing movement control to lower or raise the ram shaft by a motor based on a processing program,
Storing the ram start-up waiting time in the storage means for each stroke length from the starting point of the ram to the descending end; and
Calculating the stroke length of the ram shaft that is controlled to move based on the machining program;
Extracting the ram start waiting time corresponding to the stroke length calculated in the previous step from the storage means;
Waiting for the movement control until the extracted activation waiting time elapses when the next ram is activated; and
A press machine control method with a motor load reduction function, wherein, when the standby time has elapsed, press movement is performed by continuing movement control of the ram shaft.   The start waiting time for each stroke length is shorter as the stroke is shorter, and conversely, as the stroke is longer, the start waiting time is longer. Press machine control method with motor load reduction function.   The start waiting time for each stroke length stored in the storage means is stored for each top dead center, second top dead center, or starting point of the rising end ram. The press control method with a motor load reduction function as described. In a control device of a press machine that performs press processing while performing movement control to lower or raise the ram shaft by a motor based on a processing program,
Storage means for storing the ram start-up waiting time corresponding to each stroke length from the starting point of the ram to the descending end;
Stroke length calculation means for calculating the stroke length of the ram shaft that is movement-controlled based on the machining program;
Extracting means for extracting from the storage means the ram activation waiting time corresponding to the stroke length calculated by the stroke length calculating means;
Waiting means for waiting for the movement control until the extracted start waiting time elapses when starting the next ram;
A press machine control device with a motor load reduction function, characterized by comprising means for continuing press control of the ram shaft when the standby time has elapsed.   The start waiting time for each stroke length is shorter as the stroke is shorter, and conversely, as the stroke is longer, the start waiting time is longer. Press control device with motor load reduction function.   The start waiting time for each stroke length stored in the storage means is stored for each top dead center, second top dead center or starting point of the rising end ram. The press control apparatus with a motor load reduction function as described.

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