JP2002039931A - Material testing machine - Google Patents

Abstract

(57) [Problem] To provide a material testing machine having good motor power transmission efficiency, low cost, and capable of always accurately controlling a drive mechanism without causing backlash. A ball screw (21a) is used as a drive mechanism (2) for moving one gripping tool (3a) of a pair of gripping tools (3a, 3b) gripping a test object (W1, W2) to / from the other.
And a motor 22 for rotating the screw shaft 211a, and an output shaft 22 of the motor 22
By directly connecting a to the screw shaft 211a, the loss due to the presence of the belt transmission mechanism and its This eliminates the operation of adjusting the belt tension, and eliminates the position detection error of the gripping tool 3a due to backlash caused by the occurrence of a gap in the engagement portion between the timing belt and the pulley.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a material testing machine,
In particular, the present invention relates to a material testing machine suitable for evaluating insertion / extraction force and insertion / extraction durability of a connector and an insertion / extraction structure such as an IC card.

[0002]

2. Description of the Related Art Conventionally, as a material testing machine for evaluating the insertion / extraction force and insertion / extraction durability of a connector and an IC card, etc., a pair of gripping tools opposed to each other have been provided, and one of them has been moved closer to the other. 2. Description of the Related Art There is known a structure having a drive mechanism for separating them.

In this type of material testing machine, for example, a connector is mounted on one gripper, and an IC card is mounted on the other gripper, and the two grippers are repeatedly approached / closed by a drive mechanism.
By separating the connector, the connector and the IC card are repeatedly inserted and removed, and the insertion / extraction force and the insertion / extraction durability are evaluated.

As the driving mechanism, a mechanism including a servomotor as a driving source and a ball screw or the like for converting the rotation of the servomotor into a linear motion and displacing the gripping tool on the moving side is employed. Is conventionally configured to be transmitted to a screw shaft of a ball screw via a belt transmission mechanism using a timing belt. The displacement of one gripper is detected by detecting the rotation of the servomotor using an encoder attached to the servomotor, and the displacement of one gripper is feedback-controlled using the detection output. ing. Further, the load acting on the test object at the time of insertion and removal is detected by, for example, a load cell mounted on the other gripping tool. In addition,
The load may not be used when simply evaluating the insertion / extraction durability.

[0005]

By the way, in the conventional material testing machine provided with the above-described drive mechanism, the tension of the belt of the belt transmission mechanism for transmitting the rotation of the servomotor to the screw shaft, the timing belt, and the like. The transmission efficiency of the motor torque and rotation deteriorates due to the loss due to the engagement with the timing pulley and the like. Therefore, in order to satisfy the required specification torque, it is necessary to use a slightly larger motor in consideration of the loss, which has caused an increase in cost. In addition, since it is necessary to control the belt tension, an adjustment operation for that is necessary, which also causes a cost increase.

Further, there is a case where a gap is formed at the engagement portion between the timing belt and the timing pulley. In this case, the output of the encoder for detecting the rotation of the motor is correctly output due to the backlash caused by the gap. Does not appear, which causes a problem that the displacement of the gripper deviates from the target value.

[0007] The present invention has been made in view of such circumstances, and has a good motor power transmission efficiency, and can use a motor one size smaller than conventional motors to satisfy the same specifications. It is an object of the present invention to provide a material testing machine which is inexpensive and can always accurately control a driving mechanism without causing backlash.

[0008]

In order to achieve the above object, a material testing machine according to the present invention is provided with a pair of gripping tools for gripping a test object, and one of the gripping tools is provided. In a material testing machine provided with a drive mechanism for applying a displacement to a test object by approaching / separating from the other gripper, the drive mechanism may be a ball screw in which a nut is fixed to the one gripper. And a motor for rotating the screw shaft of the ball screw, and the output shaft of the motor is directly connected to the screw shaft.

The present invention is intended to achieve an intended object by directly connecting a belt transmission mechanism without interposing a belt transmission mechanism between a motor as a driving source and a screw shaft of a ball screw.

That is, by directly connecting the motor and the screw shaft of the ball screw, the output of the motor can be transmitted to the screw shaft with high efficiency close to 100%, and the timing belt and the timing pulley are engaged. There is no occurrence of backlash due to the gap between the parts, and the displacement of one of the grippers can be reliably detected by the output of the encoder that detects the rotation of the motor, and accurate control can be performed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional front view showing a configuration of an embodiment of the present invention, and FIG. 2 is a plan view thereof.

A linear motion mechanism 21 mainly composed of a ball screw 21a and a servomotor 2 serving as a driving source for the linear motion mechanism 21 are mounted on a bed 1.
2 and a structure having a pair of grippers 3a and 3b, and one gripper 3a is
Thus, a displacement is given in a direction approaching / separating from the other gripping tool 3b.

The linear motion mechanism 21 includes a ball screw 21a,
The linear guide 2 arranged in parallel with the ball screw 21a
1b is a known device (for example, an LM actuator manufactured by THK Co., Ltd.) in which the ball screw 21a is integrated with a screw shaft 211a and a nut block 212 screwed thereto.
The nut block 212a is guided by the linear guide 21b. The screw shaft 21
1a is rotatably supported at both ends thereof via bearings on walls 211b formed at both ends of the linear guide 21b. With this configuration, by rotating the screw shaft 211a, the nut block 212a
Move linearly in the direction (x-direction) along. Further, a preload is applied between the screw shaft 211a and the nut block 212a, so that a backlash is not generated between the screw shaft 211a and the nut block 212a.

The above-mentioned one gripping tool 3a is supported by a support member 31a fixed on a nut block 212a of the ball screw 21a, and the other gripping tool 3a.
b is supported by a position adjustment mechanism 4 provided on the bed 1. The position adjustment mechanism 4 includes two directions (y direction and z direction) orthogonal to the moving direction (x direction) of one gripping tool 3a.
Is a known mechanism for adjusting the position of the other gripping tool 3b. By operating the position adjusting mechanism 4,
It can be adjusted so that the other gripping tool 3b and one gripping tool 3a are located on a straight line. Further, a load cell 5 is provided between the other gripping tool 3b and the position adjusting mechanism 4.

The output shaft 22a of the servo motor 22
Is directly connected to the screw shaft 211a of the ball screw 21a by a coupling 22b. Therefore, by rotating the servomotor 22, the screw shaft 211a is directly rotated, whereby the nut block 212a moves in the x direction, and one grip 3a approaches / separates from the other grip 3b. I do. The servo motor 22 detects an instantaneous rotation amount by an attached encoder 6, and uses the output of the encoder 6 as a detection output to displace one gripping tool 3a following a preset instantaneous target position. Servo motor 22
Is feedback controlled.

In the embodiment of the present invention described above, in order to perform the insertion / extraction test of the connector and the IC card, for example, the connector W1 is attached to one grip 3a and the IC is attached to the other grip 3b.
The card W2 is mounted, the position is adjusted in the y and z directions, and an instantaneous target value in the x direction of one gripping tool 3a is set so that the connector and the IC card are inserted and removed in an appropriate state. After that, a drive command is given. Accordingly, the output of the encoder 6 is sequentially compared with the target value, and the servo motor 22 is feedback-controlled so that the position of the one gripping tool 3a follows the instantaneous target value. The load acting on the connector W1 and the IC card W2 is detected by the load cell 5 every moment.

A remarkable point in the above embodiment is that the screw shaft 211a of the ball screw 21a is directly connected to the output shaft 22a of the servomotor 22 by the coupling 22b. As in the case of using a belt transmission mechanism using a belt, there is no displacement of the gripper 3a due to backlash due to the formation of a gap in the engagement portion between the belt and the pulley, and consistent and accurate control is performed. At the same time, the loss due to the belt transmission mechanism is eliminated, and at the same time, the cost can be reduced by eliminating the need for the belt and the pulley, and the operation for adjusting the tension of the belt becomes unnecessary.

In the above embodiment, the present invention is applied to a horizontal material testing machine in which a pair of gripping tools are horizontally opposed, but a vertical type in which a pair of gripping tools are vertically opposed. Of course, the present invention is equally applicable to a mold type material testing machine.

In the above description, the operation in the insertion / extraction test has been described. However, the material testing machine according to the present invention holds both ends of one test piece with a pair of holding tools,
It goes without saying that a test in which a tensile force is repeatedly applied to the test piece can be performed by moving one gripping tool closer to / separating from the other gripping tool by the drive mechanism.

[0020]

As described above, as a driving mechanism for moving one of a pair of grippers for gripping a DUT to / from the other, a motor for rotating a ball screw and its screw shaft. And a mechanism in which the motor is directly connected to the screw shaft of the ball screw, so if the screw shaft and the motor are connected by a belt transmission mechanism using a timing belt as in the past, In comparison, the capacity of the motor can be reduced by the amount by which the power loss due to the belt transmission mechanism is eliminated, the number of parts can be reduced, and the operation of adjusting the tension of the belt becomes unnecessary, and the cost is reduced. be able to.
In addition, there is no mismatch between the output of the encoder and the position of the gripper due to backlash caused by the generation of a gap in the engagement portion of the belt, and the position of the gripper can always be accurately controlled. .

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view showing a configuration of an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

[Explanation of symbols]

 1 Bed 2 Drive mechanism 21 Linear motion mechanism 21a Ball screw 211a Screw shaft 212a Nut block 21b Linear guide 22 Servo motor 22a Output shaft 22b Coupling 3a, 3b Gripping tool 4 Position adjustment mechanism 5 Load cell 6 Encoder

Claims (1)

[Claims] 1. A pair of grippers for gripping a DUT are provided to face each other, and a displacement is given to the DUT by moving one of the grippers closer to or away from the other gripper. In a material testing machine provided with a drive mechanism, the drive mechanism includes a ball screw having a nut fixed to the one gripper, and a motor for rotating a screw shaft of the ball screw. A material testing machine, wherein the output shaft of the above is directly connected to the screw shaft.