JP3313144B2 - Drive control device for servo motor driven press machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control apparatus for a press machine driven by a servomotor.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional press machine driven by a servomotor. In the figure, reference numeral 5 denotes a screw shaft formed of a ball screw or the like, which reciprocates the slide 1 on which the upper die 2 is mounted in the Y direction. The screw shaft 5 is driven to rotate by a servomotor 7. 3 is a lower die attached to the bolster 4, 6 is a motion conversion mechanism including gears and the like, 8 is a rotation angle of the servo motor 7, that is, a position signal θf is detected.
For example, it is formed from a pulse generator.

In such a press machine, a servo motor 7
As shown in FIG. 3 (B), the torque that must be generated is a combined torque of a mechanical drive torque component required to drive the press machine and a forming torque component required for press forming. That is, since the machine specifications such as the weight of the slide 1 and the screw shaft 5 of the press machine and the frictional resistance with various guides are determined, the mechanical drive torque component is the same as the rotational speed of the servomotor 7 except for temporary fluctuations. As shown in (A), during a certain period (time t2 to t5), it is constant, increases during acceleration between time t1 and t2, and increases at time t5 to t5.
It decreases during deceleration between six. Here, during the period from time t3 to t4, press molding is performed by the two molds 2 and 3, so that the molding torque component is superimposed on the mechanical drive torque component. In addition, as the above press machine, for example,
JP-A-2-222498 and JP-A-262884 can be mentioned.

[0004] Thus, in such a drive control apparatus for a servo motor drive type press machine, since the forming torque component is very large relative to the machine drive torque component, as shown in FIG. First based on θ
The target torque signal T1 and the second target torque signal T2 based on the forming torque signal Tpt are switched and input in a timely manner as shown in FIG. 3, and the screw shaft 5 is rotationally driven while the servo motor 7 is controlled to rotate, so that the slide 1 reciprocates. It is configured to move.

In FIG. 4, the control circuit 10 is formed in various ways. In the case of FIG. 4, the control circuit 10 comprises signal generators 11 and 13, a torque control unit 12, an inverter 14, and a current-torque conversion unit 15, In this example, the current signal I and the torque signal T
A minor loop is formed to feed back f and f, and the rotation of the servomotor 7 is controlled. A position command system and a forming torque command system are switchably connected to the control circuit 10 via a switch 16.

First, the position command system includes a position command signal generator 20, a position command signal θ, and the position (angle) of the servomotor 7 detected by a pulse generator 8 as position detecting means.
A comparator 21 for comparing the signal with the signal θf to generate a speed signal V
And a comparator 22 that compares the speed signal V with the speed feedback signal Vf generated through the differentiating circuit 23 to generate the first target torque signal T1.

On the other hand, the forming torque command system includes a forming torque command signal generator 30 and a comparator 31 which receives and compares the forming torque command signal Tpt and the torque feedback signal Tpf to generate a second target torque signal T2. Consists of Therefore, at the time of molding between times t3 and t4 in FIG. 3, the switch 16 is automatically switched as shown by the dotted line in FIG. 4, and the molding torque command system, that is, the second target torque signal T2 is input to the control circuit 10. It has been.

The mechanical drive torque component changes during acceleration and deceleration, and during a constant motor speed (time t).
2 to t3 and t4 to t5) also vary slightly, but smooth control can be achieved by using the position command signal θ from the position command signal generator 20 and the position signal θf from the pulse generator 8 as feedback signals.

However, at the time of molding between times t3 and t4,
Since the torque generated by the servomotor 7 is a large forming torque component and a fluctuating mechanical drive torque component, smooth control cannot be performed by using only the position signal θf as a feedback signal.

In view of the above, a feedback signal to be compared with the molding torque command signal Tpt in the comparator 31 is designed to be a torque feedback signal Tpf. The torque feedback signal Tpf includes, for example, a torque factor detecting unit 40 including a strain gauge mounted on a press frame and a column, a hydraulic pressure detector mounted on a hydraulic chamber, and the like.
Generally, a torque feedback signal generator including a signal conversion circuit 41 for converting the output signal P from the detector 40 into a torque feedback signal Tpf is provided.

In other words, the idea of detecting and feeding back the actual forming torque itself is that when the forming torque component (Tpf) is detected and compared with the forming torque command signal Tpf, the fluctuation of the mechanical drive torque component is swallowed. It is assumed that the second target torque signal T2 can be generated. This is based on technical grounds that if the mechanical drive torque component of the combined torque fluctuates, the forming torque component changes by the fluctuation.

[0012]

This idea is correct,
Press molding can be performed while securing a mechanical drive torque component and a predetermined molding torque component. However, the torque factor detection unit 40
Must be mounted on a press frame or the like, which makes construction difficult and costly. Moreover, since the molding torque component is indirectly detected, there is a problem that the response is low and the time delay is large. Here, speeding up and cost reduction are more strongly demanded, and solving the above problems has become an important issue.

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive control device for a servomotor-driven press machine, which is capable of speeding up the entire press machine and reducing the cost, and which is easy to handle and has wide applicability.

[0014]

According to the present invention, when the structure of a press machine is determined, the mechanical drive torque required for driving the press machine changes in value according to the acceleration of a servomotor. interest, and molding torque command signal is assumed according to the logical or practical molding torque, the mechanical drive torque that varies with the acceleration estimates calculated from the mechanical specifications has been stored in advance with the acceleration of the current, the machine The above object is achieved by generating a second target torque signal in which the fluctuation of the driving torque is corrected and inputting it to a control circuit during molding.

That is, a drive control device for a servomotor-driven press machine according to the present invention provides a control circuit including a torque control unit with a first target torque signal based on a position command signal and a second target torque based on a forming torque command signal. In the drive control device of a servo motor drive type press machine, which is formed by switching the signal and inputting in a timely manner and rotating the screw shaft while rotating the servo motor to reciprocate the slide, Specifications storage means for storing, acceleration detection means for detecting acceleration during rotation of the servomotor, and a machine required for driving the press machine at that time from the stored machine specifications and the detected acceleration. Mechanical drive torque value calculating means for calculating a drive torque value and outputting the mechanical drive torque value signal; a forming torque command signal and a mechanical drive torque signal; Characterized by providing an adder for obtaining the second target torque signal by adding the value signal.

[0016]

In the present invention having the above configuration, the second target torque signal input to the control circuit at the time of molding is obtained by adding the molding torque command signal and the current mechanical drive torque signal. That is, the acceleration detecting means detects the acceleration of the servomotor. Then, the mechanical drive torque value calculating means calculates the mechanical drive torque value at that time from the acceleration and the mechanical data stored in advance. Subsequently, the adder adds the forming torque command signal and the calculated current mechanical drive torque signal to generate and output a second target torque signal.
That is, the fluctuation of the mechanical driving torque that changes due to the acceleration can be corrected immediately. Therefore, even if the difficult-to-handle and expensive torque factor detecting unit is wiped out, the servo motor can accurately and smoothly generate the combined torque of the current mechanical drive torque and the forming torque, and with high response. Stable press molding is possible.

[0017]

An embodiment of the present invention will be described below with reference to FIG. As shown in FIG. 1, the drive control device of the present servo motor drive type press machine includes a press machine (1, 5, 7,...)
And the control circuit 10 and the position command system (20, 21, 22, 2
Conventional 3) and the switch 16 is an example (but is the same as the case of FIG. 4), specifications storage unit 51 and the acceleration detecting means (8,
53), a mechanical drive torque value calculating means 52, and an adder 32 are provided, and the present torque is changed by the acceleration (α) while sweeping the conventional torque factor detecting section [40] for detecting the actual forming torque from the press machine itself. It is configured to correct fluctuations in mechanical drive torque (Tm) and to perform high-response and accurate press forming.

The description of components common to the conventional example (FIG. 4) will be simplified or omitted.

In FIG. 1, the acceleration detecting means comprises a pulse generator 8 connected to the servomotor 7 and a second-order differentiating circuit 53. The molding torque command signal generator 30 generates a molding torque signal Tpo for a molding torque component required for press molding. Incidentally, it is understood that the conventional forming torque signal Tpt is set as a combined torque that swallows the mechanical drive torque component.

Here, the specification storage means 51 stores machine specifications D such as weight, inertia, friction coefficient, etc. of the configuration (1, 2, 5, 6, 7,...) Of the press machine. That is, it stores the factors that influence the magnitude of the torque required to drive the press machine. Also,
The value of the machine specification D changes depending on the rotation speed of the screw shaft 5 and the acceleration α of the servomotor 7 representing the moving speed of the slide 1.

Therefore, the machine data D may be stored as the starting torque, the steady torque, the braking torque, and the friction torque of the entire press machine according to the acceleration α. Further, the storage mode may be such that the acceleration α and the magnitude of the machine specification D are stored as a matrix table, or the total torque, that is, the mechanical drive torque (T
m) may be stored as a function f [for example, Tm = f (α · D)].

Next, the mechanical drive torque value calculating means 52
From the actual acceleration α at that time input from the acceleration detection means (8, 53) and the stored machine data D,
This is a means for calculating the mechanical drive torque Tm at this time (current pressure). Therefore, the mechanical drive torque value calculating means 52
And the specification storage means 51 can be integrally formed. The point is that the mechanical drive torque Tm can be calculated using the acceleration α as an input. In that sense, it is apparent that, in terms of construction of the actual apparatus, if the acceleration calculating function (53) is further added to the integration means (51, 52), the position signal θf may be input.

Next, the operation of this embodiment will be described. First, the switch 16 is switched as shown by the solid line in FIG.
The position designation system is connected to the control circuit 10.

Then, the position command signal θ is generated from the position command signal generator 20 and the comparator 22 has a differentiating circuit 2
3 receives a speed feedback signal Vf. Therefore, since the first target torque signal T1 is input to the control circuit 10, the servo motor 7 operates at times t1 to t shown in FIG.
During the period 2, the motor is accelerated while generating a torque to cover the mechanical drive torque component at the time of startup, and is rotated at a constant speed from time t2 to t3 to generate a torque corresponding to a constant mechanical drive torque component. The same applies to the case between times t4 and t5. In addition, deceleration is performed between times t5 and t6.

Here, at time t3, the switch 16 switches the forming torque command system to the control circuit 1 as shown by the dotted line in FIG.
Switch connection to 0. The second target torque signal T2 is input. That is, the adder 32 includes a forming torque signal Tpo for generating a torque corresponding to a forming torque component necessary for press forming from the forming torque command signal generator 30, and the current acceleration α by the mechanical drive torque value calculating means 52. And a mechanical drive torque value signal Tm calculated using the machine specifications D, and a second target torque signal T2 is added and generated.

[0026] In other words, to generate the actual required torque by adding the current <br/> a mechanical drive torque (Tm) (T2) to the molding torque (Tpo). In this sense, the specification storage means 51, the mechanical drive torque value calculation means 52, and the acceleration detection means (8, 53) are provided with an automatic correction control means 50 for correcting the mechanical drive torque (Tm) component fluctuating during molding. It is understood to form.

Therefore, the servomotor 7 is rotated at a constant speed as shown in FIG. 3 while generating the mechanical drive torque Tm and the molding torque Tpo during molding, and can move the slide 1 stably.

According to this embodiment, the specification storage means 51, the acceleration detection means (8, 53), the mechanical drive torque value calculation means 52 and the adder 32 are provided, and the forming torque command signal generator 30 is provided. Current in the molding torque command signal Tpo from
A second target torque signal T2 is generated by adding the current mechanical drive torque signal Tm to correct the mechanical drive torque component, and the second target torque signal T2 is used in the control circuit 1 during press molding.
0, the torque factor detecting unit (4) detects the actual press torque as in the conventional example.
It is possible to increase the speed and reduce the cost of the entire press machine while eliminating 0) and the like, and to establish a drive control device for a servo motor drive press machine that is easy to handle and has wide applicability.

The forming torque command signal generator 30 outputs a forming torque command signal Tpo required for press forming.
, An accurate signal (Tpo) can be set, and from this point, the cost can be reduced and the handling is further simplified.

Further, since it is only necessary to store the specifications of the press machine in the specification storage means 51, the applicability is wide.

Further, the acceleration detecting means (8, 53)
Since the position signal θf from the existing position detecting means 8 is detected by performing second-order differentiation, the facility load is small.

[0032]

According to the present invention, the the specifications storage unit and the acceleration detection means and a machine driving torque value calculating means and the adder provided in the molding torque command signal from the molding torque command signal generator of current machine A second target torque signal is generated by adding a drive torque signal to correct a mechanical drive torque component, and the second target torque signal is switched to a control circuit during press molding. It is possible to provide a drive control device for a servomotor-driven press machine that can increase the speed of the press machine as a whole and reduce costs while eliminating the torque factor detecting section for detecting the actual press torque, and is easy to handle and has a wide applicability. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining a press machine structure according to the present invention and a conventional example.

FIG. 3 is a diagram for explaining a relationship between a motor speed and a motor torque according to the present invention and a conventional example.

FIG. 4 is a circuit diagram for explaining a conventional example.

[Explanation of symbols]

 Reference Signs List 1 slide 2 upper die 4 bolster 5 screw shaft 7 servo motor 8 pulse generator (acceleration detecting means) 10 control circuit 12 torque controller 14 inverter 15 current-torque converter 16 switch 20 position command signal generator 21, 22 comparator Reference Signs List 23 Differentiating circuit 30 Shaping torque command signal generator 31 Comparator 32 Adder 40 Torque factor detecting unit 41 Signal conversion circuit 50 Automatic correction control means 51 Specification storage means 52 Mechanical drive torque value calculating means 53 Second order differentiation circuit (acceleration detection Means) D Machine specifications T1 First target torque signal T2 Second target torque signal Tm Machine drive torque value signal Tpo Forming torque command signal

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B30B 15/14 B30B 1/18 B30B 15/26 H02P 5/00

Claims (1)

(57) [Claims] 1. A control circuit (10) including a torque control unit (12) appropriately sends a first target torque signal (T1) based on a position command signal and a second target torque signal (T2) based on a forming torque command signal. The servo motor (7) is rotationally controlled while the screw shaft (5) is rotationally driven and the slide (1) is reciprocated while controlling the rotation of the servo motor (7). Specifications storage means (51) for storing machine specifications (D); acceleration detection means (8, 53) for detecting acceleration (α) during rotation of the servomotor (7); A mechanical drive torque required to drive the press machine at that time from the specifications (D) and the detected acceleration (α), and to output a mechanical drive torque signal (Tm); Value calculation Stage (5
2) adding the forming torque command signal (Tpo) and the mechanical drive torque value signal (Tm) to obtain the second target torque signal (T2).
A drive control device for a servomotor-driven press machine, comprising: an adder (32) for obtaining