JP2024020682A - electric press equipment - Google Patents

Abstract

The present invention provides an electric press device that can optimize the deceleration load rate and reduce variations in the stop position of a ram and the load at the time of stop even when there are differences in workpieces or press environments. [Solution] A ram 1 that performs pressurizing work on a work W, a load detection section 31 that detects the load applied to the ram 1, a target stopping load storage section 15 that stores a target stopping load value LT, and a load detection section 31 that detects the load applied to the ram 1. A stop unit 21 that stops the ram 1 when the unit 31 detects the target stop load value LT, a deceleration load rate storage unit 16 that stores the deceleration load rate R, and a load detection unit 31 that detects the deceleration load rate R and the target stop A speed control unit 22 that controls the speed of the ram 1 to be decelerated to a set speed VL when a load value multiplied by the load value LT is detected, the speed of the ram at the target stopping load value LT, and the setting. The electric press apparatus includes a determination unit 23 that determines whether the deceleration load rate R is appropriate based on the result of comparison with the speed VL. [Selection diagram] Figure 3

Description

The present invention relates to an electric press device.

2. Description of the Related Art An electric press device is known that uses an electric motor such as a servo motor as a drive source to move a ram up and down and presses an object with the ram (for example, see Patent Document 1).

JP2022-33563A

In the electric press device, a drive stop mode such as "load stop" is set. In "load stop", the drive command is stopped when the set "target stop load value" is detected, but at this time, a phenomenon may occur in which the ram overshoots from the position where it should stop. Since the ram advances by the overshot distance and then stops, the load also exceeds the set "target stopping load value" accordingly. The overshoot distance generally depends on the drive speed of the ram, with the higher the drive speed, the greater the overshoot distance.

In order to reduce this kind of overshoot phenomenon, a method is available that decelerates to a preset value or a fixed value "set speed VL" and pressurizes when the "deceleration start load value" is detected. has been done. In this method, instead of directly specifying the "deceleration start load value", the "deceleration start load value" is set by setting the "deceleration load rate" expressed as a percentage of the "target stopping load value". . That is, the "deceleration start load value" can be expressed as "target stop load value x deceleration load rate".

Originally, it would be sufficient if the ram could be quickly decelerated to the set speed VL for deceleration when the set value of the "deceleration start load value", that is, "target stop load value x deceleration load rate" satisfies a predetermined set value. However, in reality it takes some time to slow down the ram. Therefore, if the set value of the "deceleration load rate" is not appropriate, the ram speed will reach the "target stop load value" before it decelerates to the set speed VL during deceleration, and as a result, when the drive command is stopped. The speed of the ram varies. This variation causes variation in the overshoot distance, resulting in variation in the overshoot load, and as a result, causes the ram stop position and load value to vary unnecessarily.

Furthermore, the appropriate value for the "deceleration load rate" that is set to reduce work time and overshoot will vary depending on the workpiece and press environment. Even if you are operating with a "deceleration load rate" that remains within the allowable range, if you add equipment or make small changes to the workpiece, the variation will increase and the allowable range will increase. may exceed. If press operation is performed without confirming that the deceleration load rate exceeds the allowable range, variations in the ram stop position and load may become large.

In view of the above problems, the present invention has developed an electric press that can optimize the deceleration load rate and reduce variations in the ram stop position and the load at the time of stop, even when there are differences in workpieces and press environments. Provide equipment.

In order to solve the above problems, according to an embodiment of the present invention, a ram that performs pressurizing work on a workpiece, a load detection section that detects the load applied to the ram, and a target stopping load value of the ram that is stored. a deceleration load rate storage unit that stores a deceleration load rate at which the ram starts decelerating before the target stopping load value, which is expressed as a percentage of the target stopping load value; and a load detection unit. , a speed control section that controls the speed of the ram to be decelerated to a set speed from the time when a load value obtained by multiplying the deceleration load rate and the target stopping load value is detected, and the speed of the ram at the target stopping load value. , and a determination unit that determines whether the deceleration load rate is appropriate based on a comparison result with a set speed.

According to the present invention, an electric press device is provided that can optimize the deceleration load rate and reduce variations in the ram stop position and load when stopped even when there are differences in workpieces or press environments. can.

1 is a perspective view showing an example of an electric press device according to an embodiment of the present invention. 1 is a sectional view showing the configuration of a mechanical part of an electric press device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration example of a controller part and its peripheral parts of an electric press apparatus according to an embodiment of the present invention. It is a graph showing an example of the relationship between the ram load and speed when the deceleration load rate is appropriate. It is a graph showing an example of the relationship between ram load and speed when the deceleration load rate is not appropriate. It is a graph showing how the load of the ram varies when the deceleration load rate is not appropriate. It is a flowchart which shows the 1st example (automatic setting method) of the calculation method of the deceleration load rate of the electric press apparatus based on embodiment of this invention. 8 is a graph showing an example of the result when the termination condition δ=2 is set and the deceleration load rate is calculated according to the flowchart of FIG. 7. 8 is a graph showing an example of the result when the termination condition δ=4 is set and the deceleration load rate is calculated according to the flowchart of FIG. 7. It is a flowchart which shows the 2nd example (semi-automatic setting method) of the calculation method of the deceleration load rate of the electric press apparatus based on embodiment of this invention. It is a graph which shows the example of the relationship between the load of a ram, and speed when calculating|requiring the speed of a ram based on Formula (1). It is a graph showing an example of the relationship between the load of the ram and the speed when the speed of the ram is determined using the least squares method. It is a graph showing an example of the relationship between load and speed when driving is executed multiple times under the same conditions.

Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings below, the same or similar parts are denoted by the same or similar symbols. The embodiments shown below are illustrative of devices and methods for embodying the technical idea of this invention. It is not something specific.

<Structure of electric press device>
The electric press apparatus according to the embodiment of the present invention includes a main body mechanical part as shown in FIGS. 1 and 2, and a controller part as shown in FIG. 3. The mechanical part of the main body includes a conversion mechanism that converts rotational force into linear operation of the press ram 1 using a screw mechanism. For example, as shown in FIG. 2, the conversion mechanism includes a press ram 1 that applies a desired pressure to a workpiece W (workpiece) by linear operation, and a ball screw 2 that provides linear operation to the ram 1. , these are provided inside the main body upper part 4 of the press device.

The ram 1 is provided inside the main body upper part 4. A servo motor 3 as an electric motor for providing power to the ram 1 is also provided in the upper part 4 of the main body. The drive of the servo motor 3 is transmitted to the ball screw 2 via a pulley and a belt. The upper part 4 of the main body is fixed to a column 7 arranged at the lower part of the upper part 4 of the main body, and the column 7 is fixed to a base 8. The base 8 is made of a material such as aluminum or iron, and a workpiece W to be pressed is placed on the base 8. The guide portion 6 extends along the axial direction adjacent to the ram 1 and is configured to guide the ram 1 along the axial direction. Switches 9a and 9b are connected to the ends of the base 8, which are operated by an operator when starting or stopping the pressing operation of the work W.

The ram 1 has a cylindrical body with a hollow part formed along the axial direction inside the cylindrical body, and the screw shaft 2a of the ball screw 2 can be inserted into the hollow part. A nut body 2b of a ball screw 2 is fixed to an end in the axial direction of the cylindrical body of the ram 1. A strain-generating column 1b is configured to be freely attached to the tip of the cylindrical main body. The strain-generating column 1b comes into contact with the workpiece W to apply appropriate pressure. A strain gauge is arranged so as to be attachable to the strain-generating column 1b, and the load value applied to the workpiece W can be detected by this strain gauge.

FIG. 3 is a schematic diagram of the vicinity of a controller (control mechanism) that controls the mechanical parts of the main body shown in FIGS. 1 and 2. FIG. The controller includes a processor (CPU) 20. A control program storage section 11 , a display section 12 , an operation section 13 , a primary storage section 14 , a target stopping load storage section 15 , and a deceleration load rate storage section 16 are connected to the processor 20 .

The control program storage unit 11 stores various control programs for controlling the processor 20. The display unit 12 displays processing results, such as graphs shown in FIGS. 4 to 6, showing the relationship between the speed of the ram 1 and the detected load on the ram 1. The operation unit 13 is composed of a mouse, a keyboard, etc., through which various parameters necessary for operating conditions of the ram 1 and press processing of the workpiece W can be input. The primary storage unit 14 is composed of a memory or the like that can store temporary data during the calculation process.

The target stop load storage unit 15 stores a target stop load value (Load of Target) LT[N] that is a target load when stopping the press operation of the ram 1. The deceleration load rate storage unit 16 stores the deceleration load rate (Ratio) R [%] when deceleration of the ram 1 starts before the target stopping load value, which is expressed as a ratio (%) to the target stopping load value. .

The processor 20 is further connected to a load detection section 31, a command pulse generator 32, a servo motor driver 33, and an encoder position counter 35, which are connected to the strain column 1b. The load detection unit 31 amplifies a signal corresponding to a change in resistance of the strain gauge attached to the strain column 1b, converts the analog signal into a digital signal through A/D conversion processing, and outputs the converted signal to the processor 20. The command pulse generator 32 generates a desired drive command pulse based on the command from the processor 20 and outputs the drive command pulse signal generated via the processor 20 to the servo motor driver 33 . Then, by driving the servo motor 3 under the control of the servo motor driver 33, the ram 1 is moved up and down.

Servo motor 3 is connected to encoder 34 . The encoder 34 is for detecting the rotation angle of the servo motor, and functions as a position detection section that detects the position of the ram 1. The information from the encoder 34 provides position information to the servo motor driver 33 in order to perform feedback control. Further, the position information of the encoder 34 is output to the processor 20 via the encoder position counter 35, so that the position of the ram 1 can be detected.

The processor 20 includes a stop section 21, a speed control section 22, a determination section 23, a search section 24, and a notification section 25. The stop unit 21 sends a control signal to the servo motor 3 to stop the servo motor 3, which is an electric motor, when the load detection unit 31 detects a target stop load value LT for stopping the pressurizing work of the ram 1. The ram 1 is stopped by outputting an output to the servo motor 3 to stop the servo motor 3. The speed control unit 22 controls the speed of the ram 1, and when the load detection unit 31 detects a deceleration start load value which is a load value obtained by multiplying the deceleration load rate R and the target stop load value LT, the speed control unit 22 determines the target stop load. Controls the speed of ram 1 at value LT to be decelerated to a set speed (Velocity of Low) VL [mm/sec] that is lower than the preset pressing speed (Velocity of Pressing) VP [mm/sec]. do.

The determination unit 23 compares the speed of the ram 1 at the target stopping load value LT and the set speed VL during deceleration, and determines whether the deceleration load rate R is appropriate based on the comparison result, that is, the speed It is determined whether or not the ram 1 is being decelerated correctly by the control unit 22. The determination unit 23 determines that the deceleration load rate R is appropriate when the speed of the ram 1 at the target stopping load value LT is equal to or lower than the set speed VL. On the other hand, if the speed of the ram 1 at the target stopping load value LT is greater than the set speed VL during deceleration, the determination unit 23 determines that the deceleration load rate R is not appropriate.

If the deceleration load rate R is not appropriate, the ram 1 will overshoot from the position where it should stop, causing variations in the stopping position of the ram 1 and the load at the time of stopping. When the speed of the ram 1 at the target stopping load value LT is larger than the set speed VL during deceleration, the search unit 24 changes the value of the deceleration load rate R in stages, and changes the deceleration load rate R after the change. By conducting a test in which the press operation of the ram 1 is executed at the time, an appropriate deceleration load rate R for properly decelerating the ram 1 before the stop position is searched and found.

The notification unit 25 notifies the operator, for example, via the display unit 12, that the deceleration load rate R is inappropriate when the speed of the ram 1 at the target stopping load value LT is higher than the set speed VL. As a result, it is possible to prompt the operator to optimize the deceleration load rate R, so even if there are differences in the workpiece W or press environment, it is possible to deal with variations in the stop position of the ram 1 and the load at the time of stop. can be done at an early stage.

When the ram 1 is in operation, a drive command is given to the servo motor driver 33 by the control program stored in the control program storage unit 11, and thereby the ram 1 is driven at a speed (also referred to as "pressurizing speed") VP. do. When the load value detected by the load detection unit 31 reaches the deceleration load value, which is the value obtained by multiplying the deceleration load rate R and the target stopping load value LT, the speed VP of the ram 1 becomes the set speed VL. , start decelerating. Thereafter, when the load value detected by the load detection section 31 reaches the target stop load value LT, the stop section 21 stops the servo motor 3 to stop driving the ram 1.

FIG. 4 is a graph showing the relationship between the load value (detected load) of the ram 1 and the speed when the ram 1 is appropriately decelerated and stopped. Here, as the setting conditions, the speed of ram 1 (pressurizing speed) VP = 5 mm/sec, the set speed during deceleration VL = 1 mm/sec, the target stopping load value LT = 10000 N, and the deceleration load rate R = 90%. An example of the case is shown below. In the example shown in FIG. 4, as expected, the vehicle is decelerated to 1 mm/sec, reaches 10,000 N, and stops. In the example of FIG. 4, it can be evaluated that an appropriate deceleration load rate R is set.

On the other hand, FIG. 5 shows an example in which the deceleration load rate R is not appropriate. The setting conditions are the same as the example in FIG. In Fig. 5, the speed of ram 1 starts to decelerate when the deceleration load rate R is 9,000N multiplied by the target stopping load value LT, but before the set speed during deceleration reaches VL = 1 mm/sec. The target stopping load value of 10,000N has been reached. In fact, in FIG. 5, the target stopping load value LT is reached when the ram 1 is decelerated to 3 mm/sec. When the drive of the ram 1 was stopped, overshoot occurred and the ram 1 stopped at a load value of 10,300N.

The problem in FIG. 5 is not that the overshoot load is simply increased. The speed at which the target stopping load value LT is reached changes due to differences in the workpiece and press environment, which may result in variations in the pressurizing speed. Then, variations in the pressurizing speed cause variations in the overshoot distance, which eventually appears as variations in the load overshoot.

FIG. 6 shows an example in which overshoot load variations occur because the setting of the deceleration load rate R is inappropriate. The graph of FIG. 6 shows three examples of driving operation results. The solid line shows the same results as the operating behavior in FIG. In the example shown by the dotted line above the solid line, the speed of the ram 1 at the time when the target stopping load value LT10,000N is detected is as high as 4 mm/sec. Therefore, it can be seen that both the overshoot distance and the overshoot load when the ram 1 stops increases, and the load exceeds by about 400N. Further, in the example shown by the dashed line below the solid line, the speed when the target stopping load value LT is 10,000N is as low as 2 mm/sec, and the overshoot load is also small and is within about 200N.

The problem in FIG. 6 is that the target stopping load value LT of 10,000 N is obtained before the deceleration starts at 9000 N and the speed drops to 1 mm/sec, so the overshoot of the load varies.

If a phenomenon as shown in FIG. 6 occurs, the problem can be improved by lowering the deceleration load rate R. If the deceleration load rate R is lowered, for example from R = 90% to R = 80%, deceleration will start at 10,000N x 80% = 8,000N, which means that the load of ram 1 will be lower than in the case of 9000N. It will be before the stop position. As a result, it takes a longer time to reach the target stopping load value LT = 10,000N, so after decelerating to 1 mm/sec, which is the set speed VL during deceleration at the target stopping load value LT, the target stopping load value LT will be able to reach.

The validity of the deceleration load rate R can be determined by checking the speed of the ram 1 when the target stopping load value LT=10,000N is reached. That is, when the target stopping load value LT is reached, if the speed of the ram 1 is the set speed during deceleration VL = 1 mm/sec, the deceleration load rate R is appropriate, and if it is greater than 1 mm/sec, It can be determined that the deceleration load rate R is not appropriate.

Generally, if the deceleration load rate R is made smaller, the reliability of decelerating the speed of the ram 1 to the set speed VL during deceleration by the time the ram 1 stops increases, but the distance to be decelerated and driven becomes longer. Therefore, the pressurization time becomes longer, the takt time becomes longer, and the productivity decreases. At present, the deceleration load rate R is set based on the experience and intuition of experienced persons, and an appropriate method for setting the deceleration load rate R has not been established.

As a tool for setting the deceleration load rate R to an appropriate value, for example, there is PC application software that analyzes time series data. Time series data is a sequence of values of positions and detected loads sampled at regular time intervals, for example, at 1 msec intervals. The PC application software has the function of performing a trial pressure machining operation during the setup stage, importing the time-series data from that time, and displaying this as a position-load graph. It is mainly used to verify the validity of judgment functions and judgment values. Here, the judgment function specifies the position range, upper limit load, and lower limit load as set values, and detects whether the position and load during actual machining work passes within this judgment frame, and detects whether the position and load in actual machining work pass within this judgment frame. This function outputs an error when the error occurs.

However, such PC application software is difficult to use for the purpose of verifying the validity of the set value of the deceleration load rate R. As a result, experienced people have used spreadsheet software to find reasonable values based on this time-series data.

On the other hand, according to the electric press device according to the embodiment of the present invention, it is determined whether the deceleration load rate R is appropriate based on the comparison result between the speed of the ram at the target stopping load value LT and the set speed VL. By providing the determination unit 23 that determines whether the ram 1 is in the same position or not, the deceleration load rate R can be optimized even when there are differences in the workpiece W or the press environment, and variations in the stop position of the ram 1 and the load at the time of stop can be reduced. It is possible to provide an electric press device that can do this.

<Automatic search method for deceleration load rate R by search unit 24>
An example of an algorithm for a specific method of searching for the deceleration load rate R is shown in the flowchart of FIG. This algorithm is based on dichotomy. Here, a method will be described in which the deceleration load rate R% is increased or decreased by the deceleration load rate adjustment width ΔR%, and the deceleration load rate adjustment width ΔR% is halved.

In step 71, the search unit 24 sets an initial value of the deceleration load rate adjustment range ΔR [%]. The initial value can be, for example, a negative value, for example -16 [%]. Next, in step 72, the search unit 24 sets an initial value of the deceleration load rate R [%]. The initial value can be, for example, 84[%]. Next, in step 73, the ram 1 is operated for press processing using the initial values set in steps 71 and 72. In step 74, based on the data of the position of the ram 1 and the load of the ram 1 detected by the encoder position counter 35 and the load detection unit 31, the search unit 24 determines when the load of the ram 1 reaches the target stopping load value LT. Calculate the speed of ram 1.

In step 75, the determination unit 73 determines whether the calculated speed of the ram 1 is greater than the set speed VL. If the calculated speed of the ram 1 is greater than the set speed VL, the determination unit 73 determines that this deceleration load rate R is not an appropriate value, and proceeds to step 76. In step 76, the search unit 24 updates the deceleration load rate R so that the deceleration load rate R becomes R+ΔR, and the process returns to step 73. As mentioned above, ΔR has a negative value. Here, the deceleration load rate R is lowered in stages until it reaches a reasonable value within the deceleration load rate adjustment range ΔR.

In step 75, if the calculated speed of the ram 1 is less than or equal to the set speed VL, this indicates that the ram 1 is being decelerated appropriately and the deceleration load rate R is an appropriate value. . In this case, the process advances to step 77. In step 77, the search unit 24 sets the deceleration load rate adjustment range ΔR to 1/2 and to a positive value.

In step 78, the search unit 24 updates the deceleration load rate R so that the deceleration load rate R becomes R+ΔR, and the process proceeds to step 79, where the press processing operation of the ram 1 is executed at the updated deceleration load rate R. be done. In step 80, based on the data of the position of the ram 1 and the load of the ram 1 detected by the encoder position counter 35 and the load detection section 31, the search section 24 determines when the load of the ram 1 reaches the target stopping load value LT. Calculate the speed of ram 1.

In step 81, the determination unit 73 determines whether the calculated speed of the ram 1 is greater than the set speed VL. If the calculated speed of the ram 1 is greater than the set speed VL, the determination unit 73 determines that the deceleration load rate R is not a valid value (unsuitable), and proceeds to step 82. In step 82, the deceleration load rate adjustment range ΔR is halved to a negative value. In step 83, the determination unit 73 determines whether the absolute value of the deceleration load rate adjustment width ΔR is smaller than the preset termination condition width δ. If the absolute value of the deceleration load rate adjustment width ΔR is not smaller than the termination condition width δ, the process returns to step 73. If the absolute value of the deceleration load rate adjustment width ΔR is smaller than the end condition width δ, the process returns to step 84. The termination condition width δ [%] is a preset value of ΔR at the time of termination, and when the absolute value of ΔR becomes smaller than δ, the process proceeds to step 84. Next, in step 84, since the deceleration load rate R is an inappropriate value, it is returned to the previous appropriate value. Here, since ΔR is half negative, the deceleration load rate R is reset to an appropriate value by doubling and adding the value, and the process proceeds to step 87, where the process ends.

On the other hand, if the calculated speed of the ram 1 is not greater than the set speed VL, it is determined that this deceleration load rate R is appropriate (appropriate), and the process proceeds to step 85. In step 85, the search unit 24 halves the deceleration load rate adjustment width ΔR to make it positive. In step 86, the determination unit 73 determines whether the absolute value of the deceleration load rate adjustment width ΔR is not smaller than the termination condition width δ. If the magnitude of the absolute value of the deceleration load rate adjustment width ΔR is not smaller than the termination condition width δ, the process returns to step 78. If the magnitude of the absolute value of the deceleration load rate adjustment width ΔR is smaller than the termination condition width δ, the process proceeds to step 87 and ends.

FIG. 8 is a table showing the automatic search results for the deceleration load rate R when the end condition width δ is set to 2 in the flowchart shown in FIG. No. 1, when the initial state R = 84 and ΔR = -16, the operation result was inappropriate, so in step 76 the value of deceleration load rate R was updated to R + ΔR, and as a result, the deceleration load rate R was updated to 76%. do. No. 2, if the execution at the deceleration load rate R=68 [%] is appropriate, then ΔR and R are updated in steps 77 and 78. No. 3, ΔR has a positive value of 8, and the deceleration load rate R=76%. If the results of driving under these conditions are valid, the values are updated in steps 85 and 78. Here, in step 86, the absolute values of the termination condition width δ=2 and ΔR=8 are compared, and the termination condition is not yet satisfied. No. 4, if the operation is inappropriate with ΔR=4 and deceleration load rate R=80%, the values are updated in steps 82 and 78. No. 5, if the operation is appropriate with ΔR=-2 and quick load rate R=78%, when ΔR is halved in step 85, the termination condition of step 86 is satisfied, and the process ends in step 87. In the example of FIG. 6, the deceleration load rate R=78%.

FIG. 9 is a table showing the automatic search results for the deceleration load rate when the termination condition width δ is set to 4 in the flowchart shown in FIG. This is No. Since the operation ended when the operation result in step 4 was inappropriate, the value was returned at step 84 and the operation ended when the deceleration load rate R=76%.

According to the electric press device according to the embodiment of the present invention, the search unit 24 determines an appropriate deceleration load rate R under predetermined conditions, for example, based on the flowchart of FIG. 7, and determines the determined deceleration load rate R. An appropriate deceleration load rate R can be searched for by repeating the press process operation test. Thereby, it is possible to provide an electric press apparatus that can reduce variations in the stopping position of the ram 1 and the load at the time of stopping even when there are differences in workpieces or press environments.

<Semi-automatic search method for deceleration load rate R using notification unit 25>
FIG. 10 is a flowchart showing a modification of the method of searching for the deceleration load rate R. After starting in step 90, the operator inputs and sets the deceleration load rate R via the operation unit 13 in step 91. In step 92, the pressing process of the ram 1 is executed. The operator may also start this operation. In step 93, the determination unit 23 calculates the speed of the ram 1 at the target stopping load value LT. In step 94, the determining unit 23 compares the calculated speed of the ram 1 at the target stopping load value LT with the set speed VL, and if the calculated speed is greater than the set speed VL, the determining unit 23 determines the deceleration load rate. It is determined that R is inappropriate, and the process proceeds to step 95, where the notification unit 25 notifies the operator via the display unit 12 that the deceleration load rate R is inappropriate, and the process returns to step 91. On the other hand, if the calculated speed is less than or equal to the set speed VL, the determination section 23 determines that the deceleration load rate R is appropriate, and in step 96 the notification section 25 notifies the operator via the display section 12 to decelerate. It is notified that the load rate R is appropriate, and the process returns to step 91.

In step 95, in addition to notifying the operator via the display unit 12 that the deceleration load rate R is inappropriate, the notification unit 25 also notifies the operator via the display unit 12 that the deceleration load rate R is inappropriate. A graph of time series data representing the relationship between the speed of the ram 1 and the load (detected load) applied to the ram 1 may be displayed. Since the operator can adjust the value of the deceleration load rate R input in step 91 by referring to the displayed result of the graph, the operator can more quickly obtain an appropriate value of the deceleration load rate R.

Note that the calculated speed of the ram 1 at the target stopping load value LT calculated in steps 74 and 80 of FIG. 7 and step 93 of FIG. 10 can be calculated by the following calculation method.

The speed can be calculated from the position of the ram 1 observed at regular time intervals. For example, assume that position information of positions P1, P2, . . . is detected at a certain time Tc. At this time, the instantaneous speeds V2, V3, and VN of the ram 1 are expressed by equation (1):
V2=(P2-P1)/Tc
V3=(P3-P2)/Tc
VN=(PN-P(N-1))/Tc...Formula (1)

FIG. 11 shows a graph plotting the relationship between the speed determined based on equation (1) and the detected load. Here, the pressurizing speed VP of the ram 1 is set at 5 mm/sec, and the set speed VL during deceleration is set at 1 mm/sec.

In the speed calculation method using a simple difference as shown in equation (1), the value fluctuates as shown in FIG. 11. In reality, the speed is not fluctuating, but it is a phenomenon that appears to be the case in calculations, and it is thought that the error associated with the quantization of the position of the ram 1 is having an effect. Alternatively, such calculational fluctuations occur because the sampling time interval Tc is not completely constant. Incidentally, the sampling time interval Tc in FIG. 11 is 5 msec.

The graph of FIG. 12 shows the speed calculated as the slope of linear regression using the least squares method. In FIG. 12, it can be seen that the speed value is relatively stable. In FIG. 12, it can be seen that when the target stopping load value is 10,000N, the speed has not completely decreased to 1 mm/sec, but is about 2 mm/sec.

In order to calculate the speed of ram 1, instead of using the calculation method based on two points as in equation (1), we use m data pieces (here m = 6) as shown in equation (2). , it is also possible to assume that these m pieces of data lie on a straight line and find the slope of this straight line using the method of least squares. The calculation formula is shown in the following formula (2).

（ここで、Ｔkは時刻、Ｐkは位置、ｍはデータ個数（図１２ではｍ＝６）を示す）

(Here, Tk is time, Pk is position, and m is the number of data pieces (m=6 in Figure 12))

Since the sampling time interval Tc is 5 msec, when m=6, 5 msec x (6-1) = 25 msec, and the 6 points are on a straight line. The number m of data items may be fixed, but as the speed decreases, the amount of movement decreases, so if the number m is small, the error will become large. On the other hand, if m is made too large, the assumption that the vehicle is on a straight line becomes incorrect. Furthermore, if m is large, followability when the speed fluctuates becomes poor.

The number m of data may be variable depending on the speed. First, the speed of the ram 1 can be calculated by calculating the approximate speed using equation (1), determining the number m of data according to the calculated speed, and calculating the slope of the straight line using equation (2).

FIG. 13 shows a load-speed graph when the operation was executed multiple times (three times) under the same conditions. Even under the same conditions, the graph results will vary due to variations in the workpiece. When automatically searching for the deceleration load rate as shown in the flowchart of FIG. 7, the calculated speed for determination may actually vary as a result of the operation execution in steps 73 and 79. Therefore, in order to judge that the deceleration load rate R is "appropriate", the operation is executed multiple times (for example, 10 times) without changing the deceleration load rate R, and the judgment is made only when all of them are reasonable. Processing such as , etc. is also required. Those who judge it to be inappropriate can judge it based on just one occurrence. Thereby, it is possible to obtain a reliably appropriate deceleration load rate R [%].

Although the present invention has been described by the above embodiments, it should not be understood that the statements and drawings that form part of this disclosure limit the present invention, and various modifications are possible. For example, in the embodiment of the present invention, "load stop" was explained, but "load ramp stop" monitors the amount of change in load, especially the amount of change in load per unit distance, and stops when it exceeds a certain set value. Processing can also be considered in the same way as the present invention. In other words, by applying the above-described embodiment, it is possible to automatically calculate a reasonable "deceleration load gradient rate" in a function that sets a predetermined load gradient value ratio and decelerates when the ratio is exceeded. can.

1... Ram 1b... Strain column 2... Ball screw 2a... Screw shaft 2b... Nut body 3... Servo motor 6... Guide section 7... Support column 8... Base 9a, 9b... Switch 10... Casing 11... Control program storage section 12... Display section 13...Operation section 14...Primary storage section 15...Target stop load storage section 16...Deceleration load rate storage section 20...Processor 21...Stop section 22...Speed control section 23...Determination section 24...Search section 25...Notification section 31 ...Load detection unit 32...Command pulse generator 33...Servo motor driver 34...Encoder 35...Encoder position counter

Claims (5)

A ram that applies pressure to the workpiece,
a load detection unit that detects the load applied to the ram;
a target stopping load storage unit that stores a target stopping load value when stopping the pressurizing work of the ram;
a deceleration load rate storage unit that stores a deceleration load rate when starting deceleration of the ram before the target stop load value, which is expressed as a percentage of the target stop load value;
a speed control unit that controls the speed of the ram to be decelerated to a set speed from the time when the load detection unit detects a load value obtained by multiplying the deceleration load rate and the target stop load value;
An electric press apparatus comprising: a determination unit that determines whether the deceleration load rate is appropriate based on a comparison result between the speed of the ram at the target stop load value and the set speed. The electric press apparatus according to claim 1, further comprising a search unit that searches for the appropriate deceleration load rate when the speed of the ram at the target stopping load value is higher than the set speed. The electric press apparatus according to claim 1 or 2, further comprising a notification unit that notifies that the deceleration load rate is inappropriate when the speed of the ram at the target stopping load value is higher than the set speed. The electric motor according to claim 1 or 2, further comprising an operation unit capable of inputting a set value of the deceleration load rate based on time series data representing a relationship between the speed of the ram and the detection result of the load applied to the ram. Press equipment. Calculating the speed of the ram at the target stopping load value by applying a least squares method to time series data representing the relationship between the speed of the ram and the detection result of the load applied to the ram to find a slope. The electric press device according to claim 1 or 2, comprising:

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