JP2005138110A - Servo press - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a servo press, by which, even when a tensile load is generated at a ram in pressing with a tip jig mounted to the ram or pressing in vacuum atmosphere, precise pressurization is realized by correcting an effect of the tensile load; even when a workpiece is pressurized in a state of the workpiece being heated, precise load measurement is realized without any effect on a load detector; and no trouble of disconnection is caused. <P>SOLUTION: The servo press 1 has a servo motor 2, a screwing mechanism 4 for converting torque of the servo motor 2 into reciprocating linear movement, the ram 5 performing reciprocating linear movement through the screwing mechanism 4, and the load detector 6 for detecting a load applied to the ram 5. The load detector 6 is constituted so that it detects both compression load and the tensile load applied to the ram 5, and also mounted above the ram 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a servo press that uses a servo motor as a drive source and applies pressure to a workpiece to process the workpiece.

  Conventionally, a servo press that converts the rotational force in both forward and reverse directions by a servo motor into a reciprocating linear motion via a screw mechanism such as a ball screw, and presses the workpiece at the tip of a ram that moves up and down by the reciprocating linear motion. Various proposals have been made.

  As this type of servo press, for example, as shown in FIG. 7, a servo motor 51, a ball screw disposed in a housing 52 for converting the rotational force of the servo motor 51 into a reciprocating linear motion, and rotation of the ball screw The ram 53 that moves up and down along with the ram 53 and a load detector (load cell) 54 provided at the tip of the ram 53 are generally used. The servo press 50 is configured to be capable of pressure control so that various press processes can be performed while detecting the pressure when the workpiece is pressed by the load detector 54.

  However, since the load detector 54 of the servo press 50 is attached for the purpose of detecting the stress in the compression direction generated when the ram 53 presses the workpiece, it detects only the compression load. . Further, the load detector 54 is attached to the tip of the ram 53 that contacts the workpiece.

By the way, in press working, a tip jig according to its purpose is often attached to the tip of the ram, and there are various types of tip jigs with different weights. It is desirable that pressurization can be started after measuring the dead weight with the tip jig attached to the ram and correcting the state to zero.
Also, some press work is performed in a vacuum atmosphere, and the ram is pulled in the vacuum chamber. Therefore, in order to perform accurate pressing, it is desirable that pressurization can be started after correcting the tensile load. It is.
Furthermore, press work may pressurize the workpiece while it is heated. If a load detector is installed at the tip of the ram, the load detector will be affected by heat and the measured value will drift in temperature. Accurate measurement was impossible. In addition, when a load detector is provided at the tip of the ram, the load detector cable moves in accordance with the movement of the ram, causing a disconnection trouble.

Therefore, the inventors of the present application have conceived a servo press that can accurately press even in a wide variety of press processes. That is, the first problem of the present invention is to attach a tip jig to a ram and press it. It is an object of the present invention to provide a servo press capable of performing accurate pressurization after correcting the influence of the tensile load even when a tensile load is generated on the ram, such as when pressing in a vacuum atmosphere.
In addition, the second problem of the present invention is that the load detector can be accurately measured without being affected even when the workpiece is pressurized in a heated state, and accurate pressurization is possible. The purpose is to provide a servo press without any trouble.
Furthermore, the third problem of the present invention is to correct the influence of the tensile load even when a tensile load is generated on the ram, such as when a tip jig is attached to the ram and pressed in a vacuum atmosphere. In addition to being able to accurately pressurize, even when the workpiece is heated and heated, the load detector can be accurately measured without being affected, and accurate pressurization is possible. The purpose is to provide a servo press without any trouble.

  In order to solve the first problem of the present invention, a servo motor, a screw mechanism for converting the rotational force of the servo motor into a reciprocating linear motion, a ram capable of reciprocating linear motion by the screw mechanism, and the ram A load detector for detecting a load applied to the ram, the load detector being configured to detect both a compressive load and a tensile load applied to the ram. Servo press.

  In order to solve the second problem of the present invention, a servo motor, a screw mechanism for converting the rotational force of the servo motor into a reciprocating linear motion, a ram capable of a reciprocating linear motion by the screw mechanism, And a load detector for detecting a load applied to the ram, wherein the load detector is attached above the ram.

  Furthermore, what solves the third problem of the present invention includes a servo motor, a screw mechanism for converting the rotational force of the servo motor into a reciprocating linear motion, a ram capable of reciprocating linear motion by the screw mechanism, A load detector for detecting a load applied to the ram, the load detector being configured to detect both a compressive load and a tensile load applied to the ram, and A servo press characterized by being mounted above a ram.

  According to the first aspect of the present invention, since the load detector is configured to detect not only the compressive load but also the tensile load, when the tip jig is attached to the ram for pressing or in a vacuum atmosphere Even when a tensile load is generated in the ram, such as when performing, accurate pressure can be applied after correcting the influence of the tensile load.

  According to the invention described in claim 2, since the load detector is mounted above the ram, the load detector is not affected even when the workpiece is pressurized in a heated state. Load measurement is possible and accurate pressurization is possible. Further, since the load detector is not attached to the tip of the ram, the cable of the load detector does not move following the reciprocating motion of the ram, and disconnection trouble can be prevented.

  According to the invention described in claim 3, since the load detector is configured to detect not only the compressive load but also the tensile load, and the load detector is mounted above the ram, Even if a tensile load is generated on the ram, such as when pressing with a jig attached or pressing in a vacuum atmosphere, correct pressure can be applied after correcting the influence of the tensile load, and the workpiece Even when pressure is applied in a heated state, the load detector can be accurately measured without being affected, accurate pressure can be applied, and disconnection trouble can be prevented.

  The servo press 1 of the present invention includes a servo motor 2, a screw mechanism 4 for converting the rotational force of the servo motor 2 into a reciprocating linear motion, a ram 5 capable of reciprocating linear motion by the screw mechanism 4, and a load on the ram 5. And a load detector 6 for detecting the generated load. The load detector 6 is configured to detect both a compressive load and a tensile load applied to the ram 5 and above the ram 5. Is attached. Hereinafter, each configuration will be described in detail.

  FIG. 1 is a partial longitudinal sectional view of an embodiment of a servo press according to the present invention, FIG. 2 is a block diagram of a control unit of the servo press shown in FIG. 1, and FIGS. 3 to 6 are shown in FIG. It is the front schematic diagram for demonstrating the characteristic effect | action of another servo press.

  The servo press 1 of the present invention uses a servo motor 2 as a drive source, and has a screw mechanism 4 for converting the rotational force of the servo motor 2 into a reciprocating linear motion, as shown in FIG.

  Specifically, as the drive shaft of the servo motor 2 rotates, the gear 3a rotates, the gear 3b meshing with the gear 3a rotates, and the gear 3c meshing with the gear 3b rotates and is fixed to the gear 3c. The screw mechanism 4 (ball screw) is configured to rotate. A ram 5 having a ball nut 5a and a spline shaft 5c fastened to the ball nut case 5b is attached to the ball screw 4. When the ball screw 4 is rotated in the forward and reverse directions, the ball screw 4 is rotated accordingly. The ram 5 is configured to reciprocate linearly (in this embodiment, up and down).

  A load detector 6 for detecting a load applied to the ram 5 is attached above the ram 5 in the housing (a cylindrical body provided coaxially with the axial direction of the ball screw 4) 7. The load detector 6 is configured to detect both a compressive load and a tensile load applied to the ram 5 when the servo press 1 is used. Specifically, the load detector 6 of this embodiment is constituted by a load cell, and the upper end side of the load cell 6 is fastened to the main plate 8 extending horizontally in the upper part of the housing 7 by bolts 9a and 9b. Has been. A unit comprising a bearing 10 and collars 11 a and 11 b is inserted into the load cell 6, and is fastened to the ball screw 4 by a nut 17, and these are further assembled by a bearing retainer 12. .

  When a compressive load is applied to the ram 5, the lower end surface of the collar 11 b is pressed, and accordingly, the load cell 6 is pressed upward, and the load cell 6 is pressed against the main plate 8 and compressed. It is configured so that the compressive load is measured by detecting the distortion of the. On the other hand, the load cell 6 is pulled downward when a tensile load is applied to the ram 5, and the tensile load is measured by detecting strain when the load cell 6 is pulled from the main plate 8. Yes.

  The load detector 6 of this embodiment is constituted by a load cell, but is not limited to this. Any load detector can be used as long as it can detect the load applied to the ram. It may be used. Further, the position where the load detector is attached is most preferably the part described above, but is not limited thereto, and may be provided in any other part in the housing 7. It may be attached to a base flange 13 provided at the lower part of the base plate. However, the vicinity of the base flange 13 is not suitable for such use because the load detector may be affected by heat when the work piece is pressed in a heated state. It can be attached.

  The movement distance control of the ram 5 (spline shaft 5b) is performed by detecting the rotation amount of the servo motor 2 by a rotation detector 14 attached to the servo motor 2. As the rotation detector 14, a resolver that does not use an electronic element is used, and the rotation detector 14 is configured to be widely usable even in an environment of use such as vibration and dust mist. However, the present invention is not limited to this, and other rotation detectors such as an encoder may be used.

  The ram 5 is configured to move between a return end sensor 15 and an exit end sensor 16 provided in the housing 7, and the return end sensor 15 serves as the origin of movement of the ram 5 to return to the return end sensor 15. The distance between the end sensor 15 and the extended sensor 16 is configured to be the stroke amount of the ram 5.

Next, the configuration of the control unit 20 of the servo press 1 shown in FIG. 2 will be described.
The control unit 20 is a CPU (central processing unit) 21 that controls the servo motor 2 and feedback control by feedback from the rotation detector 14, load control by feedback from the load detector 6, the return end sensor 15 and the output sensor 15. It performs external operation input signal control including the end sensor 16 and output control of its own state signal, bidirectional communication control by RS485 communication, manual switch & result display LED control, and RS232C data transfer control. Hereinafter, each configuration will be described in detail.

  The power module (power transistor) 22 is an element that gives electric power to the servo motor 2, and the power module driver 23 is an element that gives an operation command to the power module 22. The CPU 21 determines the rotation speed, rotation direction, or rotation angle of the servo motor 2 based on signals from the load detector 6 and the rotation detector 14 and performs feedback control via the power module driver 23 and the power module 22. .

  The rotation detector driver 24 is used when the feedback control based on the signal from the rotation detector 14 is performed, and is used for controlling the moving distance of the ram 5 by recognizing the rotation angle.

  The A / D converter 25 is a unit that converts an analog signal from the load converter 6 into a digital signal. The A / D converter 25 detects stress applied to the ram 5 and is used for load control. The serial port 3 is a port used for confirming the production history and verifying the state change by communicating with the ID chip attached to the load transducer 6.

  The INPUT / OUTPUT signal driver 26 is used to control input / output signals. Basically, this system starts and stops in response to external commands, so it controls the receipt of commands (INPUT SIGNAL) from external devices necessary for this and the presentation of its current status (OUTPUT SIGNAL).

  The FRASH ROM 27 is used for storing a program necessary for its own operation and setting values that are individually set according to the contents of the press. The RAM 28 is secured as an area necessary for the operation of the program.

  The keyboard segment and the display driver 29 are used to control a pendant unit with an operation result display and a manual operation switch.

  The serial port 1 (RS232C) is a port used for outputting operation results by communication, and the serial port 2 (RS485) is a port for performing bidirectional data communication with an external device. Controls input of value information and output of operation results.

  Next, the characteristic operation of the servo press 1 of the present invention will be described sequentially. First, the control for responding to the weight fluctuation when the tip jig 30 is attached to the ram 5 shown in FIG. 3 will be described.

Prior to pressing, a tip jig 30 according to the purpose is attached to the tip of the ram 5, but since the tip jig is widely used and has a different weight, the weight of the ram 5 with the tip jig 30 attached is measured. Then, pressurization is started after the state is corrected to zero.
Specifically, prior to pressing, the weight of the ram 5 (ball nut 5a, ball nut case 5b and spline shaft 5c) and the weight of the tip jig 30 are detected by the load detector 6, and the state is corrected to zero. Then, the press is controlled to start. Since the load detector 6 in the servo press 1 of the present invention is configured so as to be able to detect a tensile load, such control is possible, and an accurate press after adapting to the weight fluctuation of the tip jig is possible. Become.

  The examples shown in FIGS. 4 and 5 are for the case where the pressing is performed in a vacuum atmosphere. More specifically, the example shown in FIGS. 4 and 5 is a case where the material 36 and the material 37 are processed by applying pressure in a vacuum state, and the ram 5 is inserted into the vacuum chamber 35. Pressurization is performed. In this case, the load detected by the load detector 6 changes as shown in Table 1 below.

  First, in a state where the ram 5 is inserted into the vacuum chamber 35 (state shown in FIG. 4), the load detected by the load detector 6 is the value p0 in the normal state. Next, when the air in the vacuum chamber 35 is sucked into a vacuum state, the ram 5 is pulled into the vacuum chamber 35 due to the difference between the outside air and the atmospheric pressure in the vacuum chamber 35, and the atmospheric pressure difference proportional to the surface area of the ram 5. The load detected by the load detector 6 decreases and becomes p1. Furthermore, as shown in FIG. 5, when the ram 5 is lowered in the direction of the arrow and brought into close contact with the material 37, the surface area of the ram 5 decreases as it comes into close contact with the material 37, so the load slightly increases to p2. The load p3 necessary for the press is applied with the state of the load p2 as the origin, and a precise pressure is applied at p4. Thus, since the load detector 6 can detect both the tensile load and the compressive load, the servo press 1 of the present invention can be used in an environment where the load fluctuates in both positive and negative directions due to changes in atmospheric pressure, such as in a vacuum atmosphere. In this case, a precise press is possible.

Furthermore, the example shown in FIG. 6 is a case where the workpiece is pressed in a heated state.
As shown in this figure, in the servo press 1 of the present invention, the load detector 6 is provided in the housing 7 and is provided at a position separated from the workpiece disposed at the tip of the ram 5. The load detector 6 is affected by heat and the measured value does not drift, and accurate detection is not disabled.

It is a partial longitudinal cross-sectional view of one Example of the servo press of this invention. It is a block diagram of the control part of the servo press shown in FIG. It is a front schematic diagram for demonstrating the characteristic effect | action of the servo press shown in FIG. It is a front schematic diagram for demonstrating the characteristic effect | action of the servo press shown in FIG. It is a front schematic diagram for demonstrating the characteristic effect | action of the servo press shown in FIG. It is a front schematic diagram for demonstrating the characteristic effect | action of the servo press shown in FIG. It is a front schematic diagram of a conventional servo press.

Explanation of symbols

1 Servo Press 2 Servo Motor 3 Gear 4 Screw Mechanism (Ball Screw)
5 Ram 5a Ball Nut 5b Spline Shaft 6 Load Detector 7 Housing 8 Main Plate 9 Bolt 10 Bearing 11 Collar 12 Bearing Press 13 Base Flange 14 Rotation Detector 15 Return End Sensor 16 Lead End Sensor 17 Nut 20 Controller 21 CPU
22 Power Module 23 Power Module Driver 24 Rotation Detector Driver 25 A / D Converter 26 INPUT / OUTPUT Signal Driver 27 FRASH ROM
28 RAM
29 Keyboard segment and display driver

Claims (3)

Servo motor, screw mechanism for converting rotational force of servo motor into reciprocating linear motion, ram capable of reciprocating linear motion by screw mechanism, and load detector for detecting load loaded on the ram And the load detector is configured to detect both a compressive load and a tensile load applied to the ram. Servo motor, screw mechanism for converting rotational force of servo motor into reciprocating linear motion, ram capable of reciprocating linear motion by screw mechanism, and load detector for detecting load loaded on the ram And the load detector is mounted above the ram. Servo motor, screw mechanism for converting rotational force of servo motor into reciprocating linear motion, ram capable of reciprocating linear motion by screw mechanism, and load detector for detecting load loaded on the ram And the load detector is configured to detect both a compressive load and a tensile load applied to the ram, and is mounted above the ram. .

Images