JP2018017578A - Material tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material tester with which it is possible to remove backlash at start of material test without adding a special mechanism.SOLUTION: A control unit 50 comprises a test information storage unit 51 in which the contents of successively executed material tests are stored in advance, a backlash monitoring unit 52 for regularly monitoring whether or not there is backlash, and a backlash removal unit 53 for executing a backlash removal operation. When it is determined that backlash exists, the backlash removal unit 53 first turns a servo motor 23 by an amount equal to a set value LB in a reverse direction to a direction in which a crosshead is moved when a material test is carried out next, and then turns the servo motor 23 by an amount equal to the set value LB in a direction in which the crosshead is moved when a material test is carried out next.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a material testing machine that performs a material test by moving a cross head by driving a motor and applying a test force to a test piece.

  FIG. 1 is a schematic diagram showing the basic configuration of such a material testing machine.

  This material testing machine is provided with a pair of left and right screw rods 12 erected so as to be rotatable between a base 11 and a cross yoke 15. The screw rod 12 is composed of a ball screw. The material testing machine also includes a crosshead 14. In the vicinity of both ends of the cross head 14, a ball screw nut 13 to be screwed with the screw rod 12 is incorporated.

  The material testing machine also includes a servo motor 23 and a rotary encoder 24 that acquires rotation information of the servo motor 23. The rotational force of the servo motor 23 is transmitted to the rotary shaft 26 via the synchronous pulley 25, the synchronous belt 28, and the synchronous pulley 27 disposed on the rotary shaft of the servo motor 23. A gear box 21 having a plurality of gears is disposed at both ends of the rotating shaft 26, and the rotating force of the rotating shaft 26 is converted into the rotating force of the pair of screw rods 12, and the pair of screw rods 12 are synchronized. Rotate. Then, the cross head 14 moves up and down by the pair of screw rods 12 rotating synchronously.

  An upper grip 31 is supported on the cross head 14 via the load cell 16. Further, a lower grip 32 is supported on the base 11. As shown by phantom lines in FIG. 1, the test piece 100 is gripped at both ends by the upper gripping tool 31 and the lower gripping tool 32. In this state, when the cross head 14 is raised, a tensile test force is applied to the test piece 100, and a tensile test as a material test is executed. Note that the compression test can be performed on the test piece by changing the upper gripper 31 and the lower gripper 32 to a platen or the like.

  In such a material testing machine, the height position of the cross head 14 is measured by the amount of rotation of the rotary encoder 24 connected to the servo motor 23 and displayed on a display unit (not shown). For this reason, when the power transmission system from the servo motor 23 to the cross head 14 expands or contracts, backlash or the like occurs, the position of the cross head 14 displayed on the display unit and the actual position of the cross head 14 There will be a difference.

  Here, the largest cause of the difference between the calculated position of the crosshead 14 displayed on the display unit and the actual position of the crosshead 14 is the power transmission system from the servo motor 23 to the crosshead 14. , Backlash occurring between a plurality of gears in the gear box 21. The amount of backlash varies depending on the configuration of the material testing machine. For example, the amount of backlash is about several micrometers to several tens of micrometers in terms of the position of the crosshead.

  Due to the presence of such backlash, for example, when the crosshead 14 is moved upward and the tensile test is performed on the test piece 100 after the crosshead 14 has moved downward, immediately after the start of the material test. When the servo motor 23 rotates, it is recognized that the cross head 14 has moved, and the position of the cross head 14 displayed on the display unit changes, but the cross head 14 has not actually moved. .

  For this reason, there is a problem that the relationship between the test force and the crosshead 14 cannot be measured correctly. Further, when the rigidity of the test piece 100 is measured from the relationship between the test force immediately after the start of the material test and the displacement of the crosshead 14 and the parameters necessary for the test force control are identified, the rigidity of the test piece 100 is There is a problem that it is evaluated too small, and appropriate test force control is not possible.

  Patent Document 1 discloses a material testing machine including a backlash removal motor that constantly applies to a screw rod a rotational force in the direction opposite to the rotational direction at the time of increased load of a drive motor that applies a load to a test piece. ing.

Japanese Utility Model Publication No. 5-39482

  In order to employ the configuration described in Patent Document 1, it is necessary to dispose a backlash removal motor separately from the servo motor for generating the test force, which complicates the apparatus configuration. Further, since it is necessary to always generate a load by the backlash removing motor, there is a problem that power is consumed during that time.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a material testing machine capable of removing backlash at the start of material testing without adding a special mechanism. .

  The invention according to claim 1 is a material testing machine for performing a material test by moving a cross head by driving a motor and applying a test force to a test piece, and moving the cross head in a first direction to make a material test. In the case where the test is performed, whether or not the motor is in a state where backlash does not exist by executing a rotation operation for continuously rotating the crosshead in the first direction by a preset removal amount. Alternatively, a backlash monitoring unit that monitors whether the backlash exists because the rotation operation is not executed, and the cross before moving the cross head in the first direction to perform the material test. When the backlash monitoring unit determines that the backlash exists when the head is moved, the motor is A backlash removing unit that rotates the crosshead in the first direction by the removal amount after rotating the crosshead in a second direction that is opposite to the first direction; , Provided.

  According to the first aspect of the present invention, since the backlash removing operation is executed by the backlash removing unit when it is determined by the backlash monitoring unit that the backlash can occur, a special mechanism is added. Therefore, it is possible to remove the backlash at the start of the material test. For this reason, it becomes possible to perform a material test more accurately.

It is a schematic diagram which shows the basic composition of a material testing machine. It is a block diagram which shows the control system of the material testing machine which concerns on this invention. 5 is a flowchart showing a backlash monitoring operation by the backlash monitoring unit 52. It is a flowchart which shows the return operation | movement which returns the crosshead 14 to an origin position. It is a flowchart which shows a backlash removal operation | movement. It is a flowchart which shows the jog operation | movement which raises / lowers the crosshead 14 only predetermined distance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing a control system of the material testing machine according to the present invention. The mechanical configuration of the material testing machine is the same as that shown in FIG.

  This material testing machine includes a CPU as a processor that executes logical operations, a ROM that stores an operation program necessary for controlling the apparatus, and a RAM that temporarily stores data during control. 50. As a functional configuration, the control unit 50 includes, as a functional configuration, a test information storage unit 51 that stores in advance the content of material tests that are continuously executed, and a backlash monitoring unit 52 that constantly monitors whether backlash exists. A backlash removal unit 53 that performs a backlash removal operation when it is determined that a backlash exists.

  The control unit 50 is connected to the servo motor 23, the rotary encoder 24, and the load cell 16 shown in FIG. Further, the control unit 50 is measured by an input unit 58 such as a keyboard for the operator to perform various inputs, the output of the rotary encoder 24 or the position of the crosshead 14 during the material test, and the load cell 16. A display unit 59 such as a liquid crystal display panel for displaying the test force and the like is also connected.

  FIG. 3 is a flowchart showing the backlash monitoring operation by the backlash monitoring unit 52.

  The backlash monitoring unit 52 always monitors whether a backlash exists. At this time, a value corresponding to the backlash amount is estimated, and a removal amount (hereinafter referred to as symbol LB) that exceeds the value is set in advance. The amount of backlash is determined by the crosshead 14 even though the servomotor 23 rotates when the crosshead 14 moves in one direction by driving the servomotor 23 and then moves in the opposite direction. Is the amount that does not move. The above LB is a value larger than the amount of backlash when considered as the amount of movement of the crosshead 14, and is an amount that can reliably remove backlash if it moves accordingly. This LB can be set to a value of about 20 micrometers in terms of the amount of movement of the crosshead 14, for example. Since the cross head 14 is driven by the rotation of the servo motor 23, the movement amount of the cross head 14 and the rotation amount of the servo motor 23 can be converted into each other. Therefore, the LB is considered as the rotation amount of the servo motor 23. It is also possible to set.

  The backlash monitoring unit 52 uses the test information stored in the test information storage unit 51 to move the crosshead 14 in the direction in which the servomotor 23 next performs a material test on the crosshead 14 (the first information according to the present invention). It is determined whether or not it has been continuously rotated by LB in the direction (step S11). Then, when the material test is performed next, if the cross head 14 is continuously rotated by LB in the moving direction, it is determined that there is no backlash (step S12). On the other hand, when the next material test is performed, the crosshead 14 is rotated in the direction moving in the direction opposite to the direction in which the crosshead 14 moves (second direction according to the present invention), or the material test is performed next. Even if the crosshead 14 is rotating in the same direction as the moving direction, it is determined that the backlash exists if it is not continuously rotated by LB (step S13). The backlash monitoring unit 52 is a software module that is always operating, and the determination of the presence or absence of backlash is constantly updated and stored as a flag inside the control unit. If it is determined that there is backlash, the flag is raised, and if it is determined that there is no backlash, the flag is defeated. Other software modules in the control unit 50 can see this flag and determine whether or not there is a backlash at that time.

  FIG. 4 is a flowchart showing a return operation for returning the crosshead 14 to the origin position.

  When the return operation for returning the crosshead 14 to the home position is executed before the test is started and the crosshead is stopped (step S21), is it determined that the backlash exists by monitoring by the backlash monitoring unit 52? It is determined whether or not (step S22). When it is determined that no backlash exists, the return operation is terminated as it is. On the other hand, when it is determined that the backlash exists, the backlash removal operation is executed (step S23), and then the return operation is terminated.

  FIG. 5 is a flowchart showing the backlash removal operation.

  When it is determined that the backlash is present after the return operation, the servo motor 23 corresponds to the set value LB in the direction opposite to the direction in which the crosshead 14 moves when the material test is performed next. It is rotated by the amount (step S31). Subsequently, the servo motor 23 is rotated by an amount corresponding to the set value LB in the direction in which the cross head 14 moves when the next material test is performed (step S32). As a result, there is no backlash. Note that the direction in which the crosshead 14 moves when the next material test is performed can be known from the test conditions stored in the test information storage unit 51.

  FIG. 6 is a flowchart showing a jog operation for raising and lowering the cross head 14 by a predetermined distance.

  Before starting the test, a jog operation is performed to move the crosshead 14 by a small distance, for example, by aligning the position of the crosshead 14 with the test piece 100. When the crosshead 14 stops (step S41), backlash It is determined whether or not it is determined by the monitoring unit 52 that the backlash exists (step S42). When it is determined that no backlash exists, the jog operation is terminated as it is. On the other hand, when it is determined that the backlash exists, the backlash removal operation is executed (step S43), and the jog operation is terminated as in the case described above.

  As described above, according to the material testing machine according to the present invention, the presence or absence of backlash is always monitored, and when backlash exists after execution of the return operation or jog operation, the backlash removal operation is executed. Backlash at the start of material testing can be removed without adding a special mechanism. For this reason, it becomes possible to perform a material test more accurately.

  In the above-described embodiment, it is preferable that the execution of the backlash removal operation is temporarily stopped by the operator operating the input unit 58 shown in FIG. 2 as necessary. That is, for example, in the case of executing a force detection operation, the above-described backlash removal operation is executed, so that the hysteresis loop in the material testing machine is canceled and correct force detection cannot be executed. It is. When such a temporary stop operation is performed by the operator, the control unit 50 does not execute the backlash removal operation by the backlash removal unit 53.

  In the above-described embodiment, the case where the present invention is applied to the return operation and the jog operation has been described. However, the both ends of the test piece 100 are gripped by the upper gripping tool 31 and the lower gripping tool 32 to actually perform the material test. The present invention can be similarly applied to other situations in which the crosshead 14 is moved in a stage before executing the above.

  In the above-described embodiment, the case where the present invention is applied to the material testing machine that holds the both ends of the test piece 100 with the upper grip 31 and the lower grip 32 and executes the tensile test has been described. The present invention may be applied to other material testing machines such as a material testing machine that executes the above.

11 base 12 screw rod 13 nut 14 cross head 15 cross yoke 16 load cell 21 gear box 23 servo motor 24 rotary encoder 31 upper grip 32 lower grip 50 control section 51 test information storage section 52 backlash monitoring section 53 backlash removal Section 58 Input section 59 Display section 100 Test piece

Claims (1)

In a material testing machine that performs a material test by moving a crosshead by driving a motor and applying a test force to a test piece,
When the material test is performed by moving the crosshead in the first direction, the motor is continuously rotated to rotate the crosshead by a preset removal amount in the first direction. A backlash monitoring unit for monitoring whether the backlash does not exist or whether the backlash exists because the rotation operation is not executed,
When the cross head is moved before the material test is performed by moving the cross head in the first direction and the backlash monitoring unit determines that a backlash exists, The motor rotates the crosshead in the second direction, which is opposite to the first direction, by the removal amount, and then rotates the crosshead in the first direction by the removal amount. A backlash remover;
A material testing machine characterized by comprising:

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