Electric press, control procedures and program

Abstract

Electrical press (100), comprehensive: - an electric motor (4); - a motor driver (13) to supply the electric motor (4) with drive energy; - a plunger (1) for performing the pressing work on a workpiece (W) with the driving force of the electric motor (4); - a target load memory (25) which stores a target load (F t ) of the plunger (1) stores; - a load detector (27) that detects an actual load (F0) exerted on the plunger (1); and - a velocity detector (30) that detects a velocity (V) of the plunger (1); and comprising: - a first estimation section (31) which, based on the detected velocity (V) of the plunger (1), estimates a distance (D v ) estimates by how much the plunger (1) travels beyond an actual stopping position after the supply of drive command pulse signals to the motor driver (13) is interrupted; - a second estimation section (34) which, based on a difference between the actual load (F0) and the target load (F t ) of the plunger (1), a remaining distance of movement (D t ) of the plunger (1) until the target load (F) is reached t ) estimates; and - an interrupter for drive command pulse signals (35) which interrupts the supply of drive command pulse signals at a time when an estimated value of the distance (D) v ) of the first estimation section equals an estimated value of the remaining distance traveled (D t ) of the second estimation section.

Description

TECHNICAL AREA

[0001] The present invention relates to an electric press, a control method and a program. BACKGROUND

[0002] In general, an electric press has drive modes, such as "stopping under load at constant speed," "difference-dependent stopping at constant speed," etc. In such drive modes, a phenomenon may occur whereby a ram extends beyond its initial stopping position (overshoot). The overshoot magnitude generally depends on the ram's drive speed. It is known that the overshoot magnitude increases with increasing drive speed.

[0003] To prevent the overshoot phenomenon, various methods are provided, such as a control system called "load rate-based delay", in which pressing takes place at a lower drive speed when a predetermined load rate is reached compared to a target load, and a control system called "stop position comparison", in which an estimated stop position of the ram is specified and pressing takes place from this position at an ultra-low speed.

[0004] To reduce the overshoot magnitude, the following method is also disclosed, in which the drive speed is adaptively changed based on the difference between target and actual load, on an increasing load tendency, among other things (see e.g. JP 3 076 755 B).

[0005] US 2012 / 0249042A1 discloses a method for controlling an electric cylinder and a control system for the cylinder that can prevent a pressurization load from significantly exceeding a target load and can reduce the pressurization time. A servo controller can adjust the rod speed and a stop load, which determines whether the rod should be stopped so that the pressurization load does not significantly exceed the target load. The servo controller drives the rod in position control mode and determines whether the pressurization load, detected by a load detector, is greater than or equal to the stop load.If it determines that the load for pressurization is greater than or equal to the load for stopping, the servo controller delivers a reversal command pulse signal to a servo amplifier, causing the stored pulses in the servo amplifier to decrease in order to stop the rod with the load, which does not significantly exceed a target load. Overview of the invention Problem to be solved by the invention

[0006] However, JP 3 076 755 B employs a technique that prevents the ram from extending by reducing the drive speed as the workpiece approaches a target. Reducing the drive speed increases the machining time, thus preventing any reduction in cycle time.

[0007] Furthermore, when a servo motor is pulse-controlled by a motor driver, the supply of command pulse signals to the motor driver may be interrupted. In this case, the plunger is generally moved a distance further forward than the position at which the supply of command pulse signals is interrupted, and then stopped. The distance traveled corresponds to the difference between a position according to the command pulses held by the motor driver at that moment and a position indicated by the motor encoder, i.e., so-called "cumulative pulses." Regarding this phenomenon, it is conceivable that the overshoot phenomenon could be prevented by simultaneously eliminating the "cumulative pulses" when the supply of command pulse signals is interrupted.

[0008] When the "cumulative impulses" are balanced, the plunger is finally stopped at the position where the supply of command pulse signals was interrupted. However, the plunger behaves in such a way that it first moves out of the position where the supply of command pulse signals was interrupted and then returns and stops.

[0009] Consequently, this behavior is unsuitable for a press used for pressing operations. If, in practice, the ram extends during bending or pressing operations and presses against the workpiece, it is pointless to subsequently return the ram to its correct position. Furthermore, the problem arises that the load value no longer reaches its maximum value when the ram stops during pressing, and this value is therefore inadequate.

[0010] In view of the above problems, the present invention aims to provide an electric press, a control method and a program wherein the pressing operation for a workpiece with an appropriate load can be carried out without increasing the cycle time. MEANS OF SOLVING THE TASK Form 1:

[0011] In at least one embodiment of the present invention, an electric press is provided comprising the features of claim 1. Form 2:

[0012] In at least one embodiment of the present invention, an electric press is provided which has the features of claim 2. Form 3:

[0013] In at least one embodiment of the present invention, an electric press is provided comprising the features of claim 3. Form 4:

[0014] In at least one embodiment of the present invention, an electric press is provided comprising the features of claim 4. Form 5:

[0015] In at least one embodiment of the present invention, an electric press with the features of claim 5 is provided. Form 6:

[0016] In at least one embodiment of the present invention, an electric press with the features of claim 6 is provided. Form 7:

[0017] In at least one embodiment of the present invention, an electric press with the features of claim 7 is provided. Form 8:

[0018] In at least one embodiment of the present invention, an electric press with the features of claim 8 is provided. Form 9:

[0019] In at least one embodiment of the present invention, an electric press with the features of claim 9 is provided. Form 10:

[0020] In at least one embodiment of the present invention, an electric press with the features of claim 10 is provided. Form 11:

[0021] In at least one embodiment of the present invention, a control method for an electric press with the features of claim 11 is provided. Form 12:

[0022] In at least one embodiment of the present invention, a program is provided for causing a computer to perform a control procedure for an electric press having the features of claim 12. EFFECT OF INVENTION

[0023] The present invention according to at least one embodiment has the advantage that the pressing operation for a workpiece with an appropriate load can be carried out without extending the cycle time. BRIEF EXPLANATION OF THE DRAWINGS Fig. Figure 1 is a view showing the construction of the electric press according to a first embodiment of the present invention. Fig. Figure 2 is a view showing the electrical construction of the electric press according to the first embodiment of the present invention. Fig. Figure 3 is a view showing the electrical construction of a central computing unit according to the first embodiment of the present invention. Fig. Figure 4 is a view showing the electrical construction of an interrupter for drive command pulse signals according to the first embodiment of the present invention. Fig. Figure 5 is a view showing processing operations in the electric press according to the first embodiment of the present invention. Fig. Figure 6 shows a relationship between a speed V and a distance to the standstill of the plunger from a time of termination of a drive command pulse signal according to the first embodiment of the present invention, if the speed V is changed as a parameter in the zero load state. Fig. Figure 7 is a view showing the electrical construction of the central computing unit according to a second embodiment of the present invention. Fig. Figure 8 is a view showing processing operations in the electric press according to the second embodiment of the present invention. Fig. Figure 9 is a view showing the electrical construction of the electric press according to a third embodiment of the present invention. Fig. Figure 10 is a view showing the electrical construction of the central computing unit according to the third embodiment of the present invention. Fig. Figure 11 is a view showing processing operations in the electric press according to the third embodiment of the present invention. FORM OF EXECUTION OF THE INVENTION<Erste Ausführungsform>

[0024] The present invention is described below according to the first embodiment with reference to Fig. 1 to Fig. 6 explained. <Aufbau der Elektropresse>

[0025] Based on Fig. 1 The construction of the electric press according to the present embodiment is explained.

[0026] As in Fig. As shown in Figure 1, the electric press 100 according to the present embodiment consists of a ram 1 for pressing, which exerts a desired pressure on a workpiece W (machining object) by raising and lowering it, and a ball screw drive 2 for raising and lowering (linear movement) the ram 1. These components are provided in a press body 3. A servo motor 4, such as an AC servo motor or similar, which serves as a drive source, is also housed in a frame at the top of a housing 5 connected to the press body 3. The drive of the servo motor 4 is transmitted to the ball screw drive 2 via pulleys and a belt.

[0027] As in Fig. As shown in Figure 1, the plunger 1 is cylindrical. Specifically, an axially extending cavity is formed in a cylindrical main body 1a, into which a screw shaft 2a of the ball screw drive 2 can be inserted. Furthermore, a nut body 2b for the ball screw drive 2 is fixed to the axial end of the cylindrical main body 1a of the plunger 1.

[0028] The front end of the cylindrical main body 1a is designed to be fitted with a bending beam 9. In practice, the bending beam 9 is placed against the workpiece W to apply pressure. The bending beam 9 is designed to be fitted with an extensometer, which can detect the pressure exerted on the workpiece W.

[0029] A cylindrical guide 6 is provided to enclose the outer circumferential surface of the cylindrical main body 1a. The cylindrical guide 6 is fixed in the housing 5 so that the plunger 1 can be raised / lowered along the cylindrical guide 6. <Elektrische Konstruktion der Elektropresse>

[0030] As in Fig. As shown in Figure 2, the electric press 100 according to the present embodiment consists of a servo motor driver 13, an encoder 14, a CPU (central processing unit) 20, a control program memory 21, a display 22, an operator 23, an intermediate memory 24, a target load memory 25, a data sequence memory 26, a circuit section 27, a drive command pulse generator 28 and an encoder position counter 29.

[0031] The control program memory 21 stores control programs for controlling the operation and processing of the entire electric press 100 by the CPU (central processing unit) 20. In the present embodiment, for example, not only a main program for the pressing operation is stored, but also the program modules described below, such as... - a program module for estimating a distance by which the plunger 1 extends after the supply of drive command pulse signals to the servo motor driver 13 is interrupted, - a program module for estimating the distance traveled by the plunger 1 until a target load is reached and - a program module for interrupting the supply of drive command pulse signals at a time when an estimated value of the program module for estimating an overshoot reaches an estimated value of the program module for estimating a stroke distance of the plunger.

[0032] Display 22 is a display device for showing various pieces of information. In the present embodiment, the display shows information such as program numbers, pressing conditions, the number of workpieces processed, etc.

[0033] The control unit 23 consists of a touchscreen, a tactile switch, and other components for setting pressing conditions, among other things. The intermediate memory 24 stores temporary data. The target load memory 25 stores a target load for the ram 1. The data sequence memory 26 stores position information obtained from the encoder position counter 29 and correlated with load values ​​determined at the bending beam 9 and in the circuit section 27.

[0034] Circuit section 27 amplifies a signal relative to a change in resistance of the strain gauge attached to the bending beam 9, converts the analog signal into a digital signal via A / D conversion, and outputs the resulting signal to the CPU (central processing unit) 20. The CPU (central processing unit) 20 determines a load value from the digital signal received by circuit section 27.

[0035] The drive command pulse generator 28 generates a desired drive command pulse based on instructions from the CPU (central processing unit) 20 and outputs it to the servo motor driver 13 via a drive command pulse signal interrupter, which is explained below. The encoder 14 is used to detect the position of the plunger 1 and is connected to the servo motor 4. The encoder position counter 29 counts a pulse signal from the encoder 14 upwards. The CPU (central processing unit) 20 determines the position of the plunger 1 from a count value of the encoder 14. <Elektrische Konstruktion der zentralen Recheneinheit>

[0036] As in Fig. As shown in Figure 3, the central computing unit 20 according to the present embodiment consists of a velocity detector 30, a first estimation section 31, a computing section 33 for load gradients, a second estimation section 34 and an interrupter 35 for drive command pulse signals.

[0037] The velocity detector 30 determines the velocity of the plunger 1 from an input signal of the encoder position counter 29 and a value of a timer (not shown) and outputs these values ​​to the first estimation section 31.

[0038] The first estimation section 31 estimates a distance by which the plunger 1 extends after the supply of drive command pulse signals to the servo motor driver 13 is interrupted.

[0039] When a load (plunger 1 according to the present embodiment) is driven by the servomotor 4, the load's displacement based on the rotation of the servomotor 4 depends on a motor rotation angle for each drive command pulse signal from the servomotor driver 13, which is determined based on the characteristics of the servomotor 4. However, during load drive, a difference (deviation) is generated in practice between a displayed position and an actual position. As a result, the so-called overshoot phenomenon occurs, whereby the load continues to move even after the drive command pulse signal is terminated. The overshoot magnitude is accordingly referred to below as the "cumulative pulse magnitude." The first estimation section 31 estimates the cumulative pulse magnitude.

[0040] Specifically, the motion quantity (cumulative momentum quantity) of the extending plunger 1 comprises a component proportional to the velocity and a component proportional to the load. The cumulative momentum quantity is therefore estimated based on formula 1, where the cumulative momentum quantity is denoted by D. vf [mm], a velocity-dependent coefficient with K v [s], the velocity of the plunger 1 with V [mm / s], a load-dependent coefficient with K f [s / N] and the load is denoted by F [N]. Dvf=Kv∗V+Kf∗F∗V

[0041] The velocity-dependent coefficient K v is the coefficient of a cumulative momentum quantity proportional to velocity. The load-dependent coefficient K fis the coefficient of a cumulative momentum quantity generated depending on the load. This latter coefficient also depends on the velocity. The cumulative momentum quantity is therefore estimated as the sum of the two coefficients. The velocity-dependent coefficient K v and the load-dependent coefficient K f These values ​​change depending on the feedback factor of the drive system or the servo motor driver 13. Therefore, these coefficient values ​​are determined in advance by measurement. Specifically, in the zero-load state (load F = 0), the velocity V is changed as a parameter, whereupon the distance from the time the drive command pulse signal is terminated until the moving load (plumb 1 according to the present embodiment) comes to a stop is measured. Fig. Figure 6 shows a concrete example of this. In Fig. 6. The gradient of the diagram line corresponds to the velocity-dependent coefficient K. vFor the load-dependent coefficient K f When the load is applied (piston 1 according to the present embodiment), the same measurement is taken as for the velocity-dependent coefficient K. v The value can be determined from the coefficient, with the exception of one term of K. v *V will be determined.

[0042] Instead of determining the cumulative pulse size from the actual speed and the load in the manner described above, the cumulative pulse size can be obtained directly from the servo motor driver 13 in real time by the CPU (central processing unit) 20, provided that the servo motor driver 13 has a function that allows a pulse size accumulated in the servo motor driver 13 to be detected and sent to the CPU (central processing unit) 20.

[0043] Furthermore, the load-dependent coefficient K fSince, according to formula 1, the influence of one element of the load F on the cumulative impulse quantity D is small, one can say that vf is limited. Based on this, the cumulative impulse size D can be calculated. v [mm] alternatively simply from the velocity-dependent coefficient K v [s] and the velocity V [mm / s] of the plunger 1 are determined according to formula 2. Dv=Kv∗V

[0044] The calculation section 33 for load gradients calculates a load gradient based on a data sequence stored in the data sequence memory 26. The calculation section 33 for load gradients calculates, as the load gradient, a first differential value of the load with respect to the change in the position of the plunger 1. Specifically, it calculates, for example, the load gradient S. f [N / mm] based on formula 3, where the load gradient is S f [N / mm], where the load is denoted by F [N] and the distance by D [mm]. Sf=dF / dD

[0045] Section 33 for calculating load gradients can also determine the load gradient by calculating a linear regression using a regression line. The load gradient S is then calculated. f [N / mm] calculated based on formula 4, where the load gradient is S f [N / mm], a data sequence regarding the position of a press point is designated by (x1, x2, ..., xn) and a data sequence regarding the load is designated by (y1, y2, ..., yn). Sf=n∑i=1nxiyi−∑i=1nxi∑i=1nyin∑i=1nxi2−(∑i=1nxi)2

[0046] The second estimation section 34 estimates the distance traveled by the plunger 1 until a target load is reached. Specifically, it estimates the distance traveled by the plunger 1 until a load is reached, as determined by the circuit section (load detector) 27, relative to a target load stored in the target load memory 25. This estimate is based on an actual load exerted on the plunger 1, determined by the circuit section (load detector) 27, and a load gradient calculated by the calculation section 33 for load gradients. A relationship according to formula 5 applies, where the actual load in the zero-load state is denoted by F0 [N], and the load gradient calculated in the calculation section 33 for load gradients is denoted by S. f [N / mm] and the determined distance traveled by the plunger 1 is denoted by D [mm]. F=F0+Sf∗D.

[0047] In formula 5, the target load is represented by F. t[N] and the distance the plunger travels until the target load F is reached t with D t The relationship shown in formula 6 is derived. Rearranging formula 6 yields formula 7 for determining the distance of movement D. t of the plunger until the target load F is reached t In formula 7, values ​​of the target load F are used. t [N], the actual load F0 [N] and the load gradient S f [N / mm] can therefore be used to determine the distance of movement D t of the plunger 1 until the target load F is reached t to be determined. Ft=F0+Sf∗Dt Dt=(Ft−F0) / Sf

[0048] The above described the procedure for determining a movement distance D. t of the plunger 1 until a target load F is reached t as a linear approximation of the load gradient S f[N / mm] explained. However, it is also possible to determine a movement distance D using a second differential value of the load relative to the distance. t of the plunger 1 until the target load F is reached t is determined by quadratic approximation.

[0049] Specifically, the load F is represented by formula 9, where S is the second differential value. sf [N / mm 2 The load formula in formula 8 applies. If the load F in formula 9 is replaced by the target load F t and the distance D through the distance D t of the plunger 1 until the target load F is reached t Substituting this, we get formula 10. Formula 10 is then transformed into a quadratic equation with respect to D. t By rearranging the equation according to formula 11 and solving it, the value D can be determined. t can be determined as shown in Formula 12. Ssf=d2F / dD2 F=F0+Sf∗D+(Ssf∗D∗D) / 2 Ft=F0+Sf∗Dt+(Ssf∗Dt∗Dt) / 2 (Ssf / 2)∗Dt∗Dt+Sf∗Dt+(F0−Ft)=0 Dt=(−Sf±Sf∗Sf+2∗Ssf∗(Ft−F0)) / Ssf

[0050] The interrupter 35 for drive command pulse signals interrupts the supply of drive command pulse signals at a time when an estimated value (cumulative pulse size: distance by which the plunger 1 extends) of the first estimation section 31 reaches an estimated value (movement distance of the plunger 1 until the target load is reached) of the second estimation section 34.

[0051] As in Fig. As shown in Figure 4, the interrupter 35 for drive command pulse signals consists of a comparator 36, a switching element SW, and a resistor R. The comparator 36 compares a cumulative pulse quantity (distance by which the plunger 1 extends) obtained from the first estimating section 31 with a movement distance of the plunger 1 until the target load is reached, obtained from the second estimating section 34, and closes the switching element SW at a time when the cumulative pulse quantity (distance by which the plunger 1 extends) reaches the movement distance of the plunger 1 until the target load is reached. When the switching element SW is closed, the input of the drive command pulse signal of the servo motor driver 13 reaches the "low" level, thereby switching off the power supply to the servo motor 4 by the servo motor driver 13. The switching element SW can be an electronic component, such as a resistor. B. a transistor, a FET (field-effect transistor) or similar device can be used.Furthermore, a Schottky diode with a smaller value V can be used instead of the resistor R. f be used. <Verarbeitungsprozesse bei der Elektropresse>

[0052] Based on Fig. 5. Processing processes for the electric press 100 according to the present embodiment are explained.

[0053] First, the CPU (central processing unit) 20 reads a target load from the target load memory 25 and stores it in the buffer memory 24 (step S101). The CPU (central processing unit) 20 then instructs the drive command pulse generator 28 to generate a drive command pulse based on the target load stored in the buffer memory 24. The generated drive command pulse signal is output to the servo motor driver 13 (step S102).

[0054] Next, the CPU (central processing unit) 20 compares the target load read from the buffer 24 with an actual load applied to the plunger 1, determined by the load detector (circuit section 27), to ascertain whether the difference between the target load and the actual load is less than or equal to a predetermined value (step S103). If the determination shows that the difference between the target load and the actual load is not less than or equal to the predetermined value ("No" in step S103), the processing returns to step S102. The determination in step S103, whether the difference between the target load and the actual load is less than or equal to the predetermined value, is performed with the intention of activating the first estimation section 31 when the actual load is reasonably close to the target load. The predetermined value should ideally be... B. be approx. 5% of the maximum pressing force.

[0055] If it is determined that the difference between target load and actual load is less than or equal to the predetermined value (“Yes” at step S103), the first estimation section 31 is activated to determine a cumulative value of the drive command pulse signal from the actual speed and the load (step S104).

[0056] Next, a load gradient is calculated by the load gradient calculation section 33 (step S105), after which the second estimation section 34 is activated. Based on the actual load exerted on the plunger 1, which was determined by the load detector (circuit section 27), and the load gradient calculated by the load gradient calculation section 33, the distance of movement of the plunger 1 is estimated until it reaches the actual load determined by the load detector (circuit section 27) relative to the target load stored in the target load memory 25 (step S106).

[0057] The interrupter 35 then determines whether the cumulative magnitude of the drive command pulse signal, corresponding to the overshoot determined by the first estimation section 31, matches the distance of movement calculated by the second estimation section 34 (step S107). If the match is confirmed ("Yes" at step S107), the output of the drive command pulse is interrupted (step S108). If the interrupter 35 determines that the cumulative magnitude of the drive command pulse signal, corresponding to the overshoot determined by the first estimation section 31, does not match the distance of movement calculated by the second estimation section 34 ("No" at step S107), the processing returns to step S102. <Wirkungen und Effekte der vorliegenden Ausführungsform>

[0058] The electric press according to the present embodiment comprises - the first estimation section 31 for estimating a distance by which the plunger 1 extends after the supply of drive command pulse signals to the servo motor driver 13 is interrupted, - the second estimation section 34, which estimates the distance traveled by the plunger 1 until a target load is reached, and - the interrupter 35 for drive command pulse signals, which interrupts the supply of drive command pulse signals at a time when an estimate of the first estimation section 31 reaches an estimate of the second estimation section 34.

[0059] Thus, pressing work can be carried out on a workpiece with an appropriate load without increasing the cycle time.

[0060] Furthermore, the first estimation section 31 estimates a distance (cumulative impulse quantity) by which the plunger 1 extends, based on the relationship between the parameters of the distance D. vf[mm], by which the plunger 1 extends, of the velocity-dependent coefficient K v [s], the velocity V [mm / s] of the plunger 1, the load-dependent coefficient K f [s / N] and the load F [N]. The distance (cumulative impulse magnitude) by which the plunger 1 extends can thus be correctly estimated by a simple calculation.

[0061] Furthermore, the first estimation section 31 can determine the distance (cumulative impulse quantity) by which the plunger 1 extends using the simpler formula based on the relationship between the parameters of the distance D. v [mm], by which the plunger 1 extends, of the velocity-dependent coefficient K v [s] and estimate the velocity V [mm / s] of the plunger 1.

[0062] Furthermore, the second estimation section 34 estimates the movement distance of the plunger 1 until it reaches an actual load detected by the load detector (circuit section 27) compared to a target load stored in the target load memory 25, based on the relationship between the parameters of the target load F. t [N], the actual load F0 [N], the load gradient S f [N / mm], of the second differential value S sf [N / mm 2 ] the load and the distance of movement D t [mm]. The distance traveled by the plunger 1 until it reaches a target load can therefore be accurately estimated by a simple calculation. <Zweite Ausführungsform>

[0063] Based on Fig. 7 and Fig. Section 8 describes an electric press 110 according to the present embodiment. The electric press 110 according to the present embodiment operates in a two-stage drive process in which the ram 1 is first stopped at a target load and then moved a certain distance to perform the pressing work. <Elektrische Konstruktion der zentralen Recheneinheit>

[0064] As in Fig. As shown in Figure 7, a central processing unit 20A according to the present embodiment consists of a velocity detector 30, a first estimation section 41, a processing section 33 for load gradients, a second estimation section 44, and an interrupter 45 for drive command pulse signals. The components with the same reference numerals as according to the first embodiment have the same functions, so their detailed explanation is omitted.

[0065] The first estimation section 41 estimates a distance (cumulative pulse size) by which the plunger 1 extends after the supply of drive command pulse signals to the servo motor driver 13 is interrupted. Without waiting for the plunger 1 to finish operating after the interruption of the drive command pulse signals by the interrupter 45 in the first drive step, the first estimation section 41 continues to estimate a further distance (cumulative pulse size) by which the plunger 1 extends, starting from a position corresponding to the distance (cumulative pulse size) estimated in the first drive step. This further estimates the distance the plunger 1 will extend after the drive command pulse signals corresponding to the distance to the target position are supplied to the servo motor driver 13.The method for estimating the overshoot is the same as that according to the first embodiment.

[0066] The second estimating section 44 estimates the distance of the plunger 1 until it reaches a target load in the first drive step. Furthermore, the second estimating section 44 estimates the distance of the plunger 1 until it reaches the target load in the second drive step without actually waiting for the plunger 1 to finish operating after the interruption of the drive command pulse signals by the interrupter 45 in the first drive step. The method for estimating the distance of the plunger 1 until it reaches the target load is the same as in the first embodiment.

[0067] The interrupter 45 for drive command pulse signals interrupts the supply of drive command pulse signals in the first drive step at a time when an estimated value (cumulative pulse size: distance by which the plunger 1 extends) of the first estimation section 41 reaches an estimated value (movement of the plunger 1 until the target load is reached) of the second estimation section 44. Furthermore, in the second drive step, it interrupts the supply of drive command pulse signals at a time when an estimated value (cumulative pulse size: distance by which the plunger 1 extends) of the first estimation section 41 reaches an estimated value (movement of the plunger 1 until the target load is reached) of the second estimation section 44. The interrupter 45 for drive command pulse signals is designed identically to that of the first embodiment. <Verarbeitungsprozesse bei der Elektropresse>

[0068] Based on Fig. 8. Processing processes for the electric press according to the present embodiment are explained.

[0069] First, in the first drive step, the CPU (central processing unit) 20A reads a target load from the target load memory 25 and stores it in the intermediate memory 24 (step S201). The CPU (central processing unit) 20A then instructs the drive command pulse generator 28 to generate a drive command pulse based on the target load stored in the intermediate memory 24. The generated drive command pulse signal is output to the servo motor driver 13 (step S202).

[0070] Next, the CPU (central processing unit) 20A compares the target load read from the intermediate memory 24 with an actual load applied to the plunger 1, determined by the load detector (circuit section 27), to ascertain whether the difference between the target load and the actual load is less than or equal to a predetermined value (step S203). If the determination shows that the difference between the target load and the actual load is not less than or equal to the predetermined value ("No" in step S203), the processing returns to step S202. The determination in step S203, whether the difference between the target load and the actual load is less than or equal to the predetermined value, is performed with the intention of activating the first estimation section 41 when the actual load is reasonably close to the target load. The predetermined value should ideally be... B. be approx. 5% of the maximum pressing force.

[0071] If it is determined that the difference between the target load and the actual load is less than or equal to the predetermined value (“Yes” at step S203), the first estimation section 41 is activated to determine a cumulative value of the drive command pulse signal from the actual speed and the load (step S204).

[0072] Next, a load gradient is calculated by the load gradient calculation section 33 (step S205), after which the second estimation section 44 is activated. Based on the actual load exerted on the plunger 1, which was determined by the load detector (circuit section 27), and the load gradient calculated by the load gradient calculation section 33, the distance of movement of the plunger 1 until it reaches the actual load determined by the load detector (circuit section 27) is estimated relative to the target load stored in the target load memory 25 (step S206).

[0073] The interrupter 45 for drive command pulse signals then determines whether the cumulative magnitude of the drive command pulse signal, corresponding to the overshoot determined by the first estimation section 41, matches the distance of movement calculated by the second estimation section 44 (step S207). If the match is confirmed ("Yes" in step S207), the output of the drive command pulse is interrupted (step S208). If the interrupter 45 for drive command pulse signals determines that the cumulative magnitude of the drive command pulse signal, corresponding to the overshoot determined by the first estimation section 41, does not match the distance of movement calculated by the second estimation section 44 ("No" in step S207), the processing returns to step S202.

[0074] If the output of the drive instruction pulse is interrupted, the CPU (central processing unit) 20A determines whether the processing steps from S201 to S208 correspond to the first or the second drive step. If it determines ("No" for step S209) that this is the first drive step, the processing process returns to step S201 to execute the processing steps from S201 to S208. If it determines ("Yes" for step S209) that this is the second drive step, the processing processes are terminated. <Wirkungen und Effekte der vorliegenden Ausführungsform>

[0075] The electric press according to the present embodiment comprises - the first estimation section 41 for estimating a distance by which the plunger 1 extends after the supply of drive command pulse signals to the servo motor driver 13 is interrupted, - the second estimation section 44, which estimates the distance traveled by the plunger 1 until a target load is reached, and - the interrupter 45 for drive command pulse signals, which interrupts the supply of drive command pulse signals at a time when an estimate of the first estimation section 41 reaches an estimate of the second estimation section 44.

[0076] In practice, it is not necessary to wait for the end of the drive during the first and second drive steps, so that the pressing work for a workpiece can also be carried out in the two-stage drive process with appropriate load, without extending the cycle time. <Dritte Ausführungsform>

[0077] Based on Fig. 9 to Fig. Section 11 describes an electric press 120 according to the present embodiment. The electric press 120 according to the present embodiment operates in a so-called differential-dependent stopping method under load, wherein a stopping process is carried out when the load gradient exceeds a target load gradient. <Elektrische Konstruktion der Elektropresse>

[0078] As in Fig. As shown in Figure 9, the electric press 120 according to the present embodiment consists of a servo motor driver 13, an encoder 14, a CPU (central processing unit) 20B, a control program memory 21, a display 22, an operator panel 23, a buffer memory 24, a memory 25A for target load gradients, a data sequence memory 26, a circuit section 27, a drive command pulse generator 28, and an encoder position counter 29. The components with the same reference numerals as according to the first embodiment have the same functions, so their detailed explanation is omitted.

[0079] The memory 25A for target load gradients stores a target load gradient according to the present embodiment. <Elektrische Konstruktion der zentralen Recheneinheit>

[0080] As in Fig. As shown in Figure 10, the central processing unit 20B according to the present embodiment consists of a velocity detector 30, a first estimation section 31, a processing section 33 for load gradients, a third estimation section 38, and an interrupter 55 for drive command pulse signals. The components with the same reference numerals as according to the first and second embodiments have the same functions, so their detailed explanation is omitted.

[0081] The third estimation section 38 estimates the distance traveled by the plunger 1 until a target load gradient is reached, based on an actual load gradient calculated by the calculation section 33 for load gradients and the target load gradient stored in memory 25A for target load gradients.

[0082] The third estimation section 38 estimates the distance traveled by the plunger 1 until the target load gradient is reached in the following manner.

[0083] First, the load gradient [N / mm] is calculated using S f , the actual load gradient [N / mm] with S f0 , the distance [mm] with D and the second differential value [N / mm 2 ] the load with S sf As indicated, a relationship according to formula 13 results between these values. Sf=Sf0+Ssf∗D

[0084] Will the distance be increased until a target load gradient S is reached? ft as D t designated and formula 13 according to D t Solving this, we get formula 14. In this way, the distance of movement D is determined. t of the plunger 1 until a target load gradient is reached. Dt=(Sft−Sf0) / Ssf

[0085] The second differential value S sfThe load can be calculated in the same way as the first differential value S. f The load can alternatively be determined from the gradient of a regression line. The second differential value S is then calculated. sf determined based on formula 15, where a position-related data sequence is denoted by (x1, x2, ..., xn) and a data sequence relating to the differential value of the load is denoted by (y1, y2, ..., yn). Sf=n∑i=1nxiyi−∑i=1nxi∑i=1nyin∑i=1nxi2−(∑i=1nxi)2 <Verarbeitungsprozesse bei der Elektropresse>

[0086] Based on Fig. 11. Processing processes for the electric press according to the present embodiment are explained.

[0087] First, the CPU (central processing unit) 20B reads a target load gradient from the target load gradient memory 25A and stores it in the intermediate memory 24 (step S301). The CPU (central processing unit) 20B then instructs the drive command pulse generator 28 to generate a drive command pulse based on the target load gradient stored in the intermediate memory 24. The generated drive command pulse signal is output to the servo motor driver 13 (step S302).

[0088] Subsequently, the load gradient computation section 33 calculates an actual load gradient (step S303). The CPU (central processing unit) 20 compares the target load gradient read from the buffer 24 with an actual load gradient calculated by the load gradient computation section 33 to determine whether the difference between the target load gradient and the actual load gradient is less than or equal to a predetermined value (step S304). If the determination shows that the difference between the target load gradient and the actual load gradient is greater than the predetermined value ("No" in step S304), the processing returns to step S302.

[0089] If it is determined that the difference between the target load gradient and the actual load gradient is less than or equal to the predetermined value (“Yes” at step S304), the first estimation section 31 is activated to determine a cumulative value of the drive command pulse signal from the actual speed and the load (step S305).

[0090] Next, the third estimation section 38 is activated to estimate the distance traveled by the plunger 1 until it reaches the load gradient determined by the calculation section 33 for load gradients compared to the target load gradient stored in memory 25A for target load gradients (step S306).

[0091] The interrupter 55 then determines whether the cumulative magnitude of the drive command pulse signal, corresponding to the overshoot determined by the first estimation section 31, matches the distance traveled until reaching the target load gradient calculated by the third estimation section 38 (step S307). If the match is confirmed, the output of the drive command pulse is interrupted (step S308). If the interrupter 55 determines that the cumulative magnitude of the drive command pulse signal, corresponding to the overshoot determined by the first estimation section 31, does not match the distance traveled until reaching the target load gradient calculated by the third estimation section 38 ("No" at step S307), the processing returns to step S302. <Wirkungen und Effekte der vorliegenden Ausführungsform>

[0092] The electric press according to the present embodiment comprises - the first estimation section 31 for estimating a distance by which the plunger 1 extends after the supply of drive command pulse signals to the servo motor driver 13 is interrupted, - the data sequence memory 26, which stores a data sequence in which a position of the plunger 1 is associated with a load exerted on the plunger 1 in that position, - the calculation section 33 for load gradients, which calculates a load gradient based on a data sequence stored in the data sequence memory 26, - memory 37 for target load gradients, which stores target load gradients, - the third estimation section 38, which, based on an actual load gradient calculated by the calculation section 33 for load gradients and a target load gradient stored in memory 37 for target load gradients, estimates the distance traveled by the plunger 1 until the target load gradient is reached, and - the interrupter 55 for drive command pulse signals, which interrupts the supply of drive command pulse signals at a time when an estimated value of the first estimation section 31 reaches an estimated value of the third estimation section 38.

[0093] Even during differential-dependent stopping under load, the extension of the ram 1 can be prevented by interrupting the supply of drive command pulse signals at the point in time when an estimated value of the first estimation section 31 reaches an estimated value of the third estimation section 38. Thus, the pressing operation for a workpiece with an appropriate load can be carried out without increasing the cycle time.

[0094] Furthermore, the third estimation section 38 estimates a value D t based on a predetermined relationship, where the target load gradient is represented by S ft [N / mm], the load gradient (actual load gradient) calculated from a first differential value or by regression calculation with S f0 [N / mm], the second differential value of the load with S sf [N / mm 2 ] and the distance traveled until the target load gradient is reached with D t[mm] is denoted. The distance traveled by the plunger 1 until a target load gradient is reached can thus be accurately estimated by a simple calculation.

[0095] The electric press according to the invention can also be implemented by recording processing steps in the electric press on a storage medium accessible to a computer system or computer, whereupon a program recorded in the storage medium is read into the electric press and executed. The computer system or computer considered here comprises an operating system and hardware, such as peripheral devices, among other things.

[0096] It is further understood that the term "computer system or computer" includes a deployment environment (or a display environment) for a homepage when a World Wide Web (WWW) system is used. Furthermore, the program in question can be transmitted from the computer system or computer, in whose memory this program is stored, to another computer system or computer via a transmission medium or by transmission waves in the transmission medium. A "transmission medium" that transmits a program is understood to be a medium with a function for transmitting information, such as a network (communication network), like the Internet, a telecommunications line (communication line), like a telephone line, etc.

[0097] The program can also serve to partially implement the aforementioned functions. Furthermore, it can be a so-called difference file (difference program) that can implement the aforementioned functions by combining them with a program already recorded in the computer system or computer.

[0098] The embodiment of the present invention has been explained in detail with reference to the drawings. However, the specific structure of the invention is not limited to this embodiment, but includes further designs within the framework of the basic concept of the invention. REFERENCE MARK LIST 1 pestle 1a Cylindrical main body 2 ball screw drive 2a Screw shaft 2b Mother's body 3 press bodies 4 servo motors 5 cases 6 Cylindrical guide 9 bending beams 13 servo motor drivers 14 encoders 20 CPUs (central processing units) 21 control program memory 22 advertisements 23 Operation 24 buffers 25 Target load storage 25A storage for target load gradients 26 Data sequence storage 27 Circuit section 28 Drive command pulse generators 29 encoder position counters 30 speed detector 31 First estimation section 33 Calculation section for load gradients 34 Second estimation section 35 interrupters for drive command pulse signals 36 comparators 38 Third estimation section 41 First estimation section 42 Second estimation section 45 interrupters for drive command pulse signals 55 interrupters for drive command pulse signals 100 electric presses

Claims

[1] Electric press (100), comprising: - an electric motor (4); - a motor driver (13) for supplying the electric motor (4) with drive energy; - a ram (1) for carrying out the pressing work for a workpiece (W) with the driving force of the electric motor (4); - a target load memory (25) which stores a target load (F t ) of the plunger (1); - a load detector (27) which detects an actual load (F0) exerted on the plunger (1); and - a speed detector (30) which detects a speed (V) of the plunger (1); and comprising: - a first estimation section (31) which, based on the detected speed (V) of the plunger (1), determines a distance (D v ) estimates the distance by which the plunger (1) moves beyond an actual stop position after the supply of drive command pulse signals to the motor driver (13) has been interrupted; - a second estimation section (34) which, based on a difference between the actual load (F0) and the target load (F t ) of the plunger (1), a remaining movement distance (D t ) of the plunger (1) until the target load (F t ) estimates; and - a drive command pulse signal interrupter (35) which interrupts the supply of drive command pulse signals at a time when an estimated value of the distance (D v ) of the first estimation section is equal to an estimate of the remaining movement distance (D t ) of the second estimation section. [2] Electric press (100) according to claim 1, wherein the first estimation section (31) estimates a distance by which the plunger (1) moves beyond the actual stop position based on formula 1, where the distance by which the plunger (1) moves out is D v [mm], a speed-dependent coefficient with Kv [s] and the speed of the ram (1) is V [mm / s]. Dv=Kv∗V [3] Electric press (100) according to claim 1, wherein the first estimation section (31) estimates a distance by which the plunger moves beyond the actual stop position based on formula 2, where the distance by which the plunger (1) moves out is D vf [mm], a speed-dependent coefficient with K v [s], the speed of the ram (1) with V [mm / s], a load-dependent coefficient with K f [s / N] and the load is denoted by F [N]. Dvf=Kv∗V+Kf∗F∗V [4] Electric press (100) according to claim 1, comprising: - a position detector (14) which detects a position of the plunger (1); - a data sequence memory (26) which stores a data sequence in which a position of the plunger (1) is associated with a load exerted on the plunger (1) in this position; and - a load gradient calculation section (33) which calculates a load gradient on the basis of a data sequence stored in the data sequence memory, wherein the second estimation section (34) calculates the remaining movement distance (D t ) of the plunger (1) until the load determined by the load detector is reached compared to the target load stored in the target load memory on the basis of - an actual load exerted on the plunger (1), which is determined by the load detector, and - the load gradient calculated by the load gradient calculation section (33). [5] The electric press (100) according to claim 4, wherein the load gradient calculating section (33) calculates, as the load gradient, a first differential value of the load with respect to the change in a position of the ram (1). [6] The electric press (100) according to claim 4, wherein the load gradient calculating section (33) determines the load gradient by regression calculation. [7] Electric press (100) according to one of claims 4 to 6, wherein the load gradient calculation section (33) further calculates a second differential value of the load with respect to the change in a position of the plunger (1), wherein the second estimation section (34) determines a value D based on formula 3 t estimates, where the target load is F t [N], the actual load with F0 [N], the load gradient with S f [N / mm], a second differential value of the load with S sf [N / mm 2] and the remaining movement distance with D t [mm]. Dt=(−Sf±Sf∗Sf+2∗Ssf∗(Ft−F0)) / Ssf [8] The electric press (100) according to any one of claims 1 to 7, wherein, in a case where the ram (1) for which a stop process has been performed once is to be further moved to a predetermined position to perform the pressing work for a workpiece (W), drive command pulse signals corresponding to the distance to the predetermined position are further supplied to the motor driver (13) from a position corresponding to a distance estimated by the first estimating section (31) by which the ram (1) moves beyond the actual stop position. [9] Electric press (120), comprising: - an electric motor (4); - a motor driver (13) for supplying the electric motor (4) with drive energy; - a ram (1) for carrying out the pressing work for a workpiece (W) with the driving force of the electric motor (4); - a load detector (27) which detects a load exerted on the plunger (1); and - a position detector (14) which detects a position of the plunger (1), and comprising: - a first estimating section (31) which estimates a distance by which the plunger (1) moves beyond an actual stop position after the supply of drive command pulse signals to the motor driver (13) is interrupted; - a data sequence memory (26) which stores a data sequence in which a position of the plunger (1) is associated with a load exerted on the plunger (1) in this position; - a load gradient calculation section (33) which calculates a load gradient on the basis of a data sequence stored in the data sequence memory (26); - a memory (25A) for target load gradients which stores target load gradients; - a third estimation section (38) which, on the basis of an actual load gradient calculated by the load gradient calculation section (33) and a target load gradient stored in the target load gradient memory (25A), calculates the remaining movement distance (D t ) of the ram (1) until the desired load gradient is reached; and - a drive command pulse signal interrupter (55) which interrupts the supply of drive command pulse signals at a time when an estimated value of the distance of the first estimating section (31) is equal to an estimated value of the remaining travel distance (D t ) of the third estimation section (38). [10] Electric press (120) according to claim 9, wherein the load gradient calculation section (33) calculates the load gradient with respect to the change in a position of the plunger (1) from a first differential value of the load or by regression calculation and calculates a second differential value of the load with respect to the change in a position of the plunger (1), wherein the third estimation section (38) based on formula 4 determines a value D t estimates, where the target load gradient is S ft [N / mm], the load gradient (actual load gradient), which is calculated from the first differential value or by regression calculation, with S f0 [N / mm], the second differential value of the load with S sf [N / mm 2 ] and a movement distance until the target load gradient is reached with D t [mm]. Dt=(Sft−Sf0) / Ssf [11] Control method for an electric press (100) with - an electric motor (4), - a motor driver (13) for supplying the electric motor (4) with drive energy, - a ram (1) for carrying out the pressing work for a workpiece (W) with the driving force of the electric motor (4), - a target load memory (25) which stores a target load (F t ) of the plunger (1), - a first estimation section (31), - a second estimation section (34), - a drive command pulse signal interrupter (35), - a load detector (27) which detects an actual load (F0) exerted on the plunger (1), and - a speed detector (30) which detects a speed (V) of the plunger (1), characterized by - a first step (S104) in which the first estimation section (31) determines a distance (D v) by which the plunger (1) moves beyond an actual stop position after interrupting the supply of drive command pulse signals to the motor driver (13), - a second step (S106) in which the second estimation section (34) calculates the load based on a difference between the actual load (F0) and the target load (F t ) of the plunger (1) the remaining movement distance (D t ) of the plunger (1) until the target load (F t ) estimates, and - a third step (S108) in which the drive command pulse signal interrupter (35) interrupts the supply of drive command pulse signals at a time when an estimated value of the distance (D v ) of the first estimation section (31) is equal to an estimated value of the remaining movement distance (D t ) of the second estimation section (34). [12] Program for causing a computer to carry out a control method for an electric press (100) with - an electric motor (4), - a motor driver (13) for supplying the electric motor (4) with drive energy, - a ram (1) for carrying out the pressing work for a workpiece (W) with the driving force of the electric motor (4), - a target load memory (25) which stores a target load (F t ) of the plunger (1), - a first estimation section (31), - a second estimation section (34), - a drive command pulse signal interrupter (35), - a load detector (27) which detects an actual load (F0) exerted on the plunger (1), and - a speed detector (30) which detects a speed (V) of the ram (1), the program causing the computer to perform the following steps: - a first step (S104) in which the first estimation section (31) determines a distance (D v ) estimates the distance by which the plunger (1) moves beyond an actual stop position after the supply of drive command pulse signals to the motor driver (13) has been interrupted; - a second step (S106) in which the second estimation section (34) calculates the load based on a difference between the actual load (F0) and the target load (F t ) of the plunger (1) the remaining movement distance (D t ) of the plunger (1) until the target load (F t ) estimates; and - a third step (S108) in which the drive command pulse signal interrupter (35) interrupts the supply of drive command pulse signals at a time when an estimated value of the distance (D v ) of the first estimation section (31) is equal to an estimated value of the remaining movement distance (D t) of the second estimation section (34).

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