JPH01118741A - Material testing machine - Google Patents

Abstract

PURPOSE:To reduce the cost by operating the output shaft of a motor intermittently at the time of low-speed operation and setting the rigidity, etc., of the material testing material in this intermittent operation. CONSTITUTION:When a set speed is set from a speed setting part 4, a pulse signal for rotating the output shaft of the motor 1 continuously is supplied from a motor driving part 7 to the motor 1. The rotating speed of this motor 1 is detected by an encoder 2 and a pulse signal of frequency proportional to the rotating speed is supplied to the controller 3, which sends a signal corresponding to the frequency shift between both input pulses to a deviation device 6. Further, a pulse signal from the encoder 2 is converted by an F/V converter 5 into a voltage value, which is inputted to the deviation device 6. Then the deviation device 6 calculates the difference between both inputs and inputs a signal corresponding to the deviation to a circuit 7. Then the circuit 7 supplies the motor 1 with a motor driving pulse having a duty ratio corresponding to the level of the input voltage signal. Then this motor 1 is driven to rotate with the motor driving signal.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a material testing machine in which a test piece is loaded by a motor. B. Prior art Figure 4 shows a conventional material testing machine. Testing machine 30
a pair of screw rods 32 erected on a table 31;
The cross head 33 screwed onto the screw rod 32 and the screw rod 3
A grip 34 is connected to the cross head 33 via a load cell 12.
The table 31 is provided with a lower grip 35. The rotation of the motor 11 is controlled by a pair of screw rods 3 via a transmission 36.
2, and the rotation of the screw rod 32 causes the crosshead 3 to rotate.
3 moves up and down, and the test piece 37 is loaded.

The transmission 36 includes a reduction gear 361 and two electromagnetic clutches 3.
62, 363, when the electromagnetic clutch 362 is connected and the electromagnetic clutch 363 is disconnected, the rotation of the motor 11 is output as is, and the electromagnetic clutch 36 is disconnected and the electromagnetic clutch 36 is connected.
When 3 is connected, the rotation of the motor 11 is decelerated and outputted. 38 is a drive gear train.

For example, if the speed range of the motor 11 is 2 to 2000 rpm, and the reduction ratio of the reducer 361 (7) is 1/100, then
The motor speed range will be 0.02-2000 rpm.

In other words, in a general material testing machine, the loading speed is 500~
This load speed range is approximately 0.5 mm/min, and this load speed range is achieved by controlling the rotation speed of the motor 11 by disengaging the electromagnetic clutch 363 and connecting the electromagnetic clutch 362. In addition, if a load speed of 0.5 mm/win or less is required, the electromagnetic clutch 362 is turned off and the electromagnetic clutch 363 is turned off.
The rotational speed of the motor 11 is reduced to 1/100 without inheriting the motor.

C0 Problems to be Solved by the Invention However, in the conventional motor control device, a mechanical transmission 36 is essential, the structure is complicated, and the transmission 36 generates gear noise and vibration. there were.

An object of the present invention is to provide a material testing machine that can obtain a wide range of load speeds only by controlling the drive of a motor without using a mechanical speed reducer.

Means for Solving the D0 Problem The material testing machine according to the present invention includes a motor for loading a test piece, a detection means for detecting the motor rotation speed, and a deviation between the target motor speed and the detected motor speed. It is equipped with a motor drive circuit that supplies a motor drive signal to the motor based on the motor drive signal, and a load detector that detects the load on the test piece. The rigidity of the material testing machine and the inertial force of the moving part of the material testing machine are set so that the loading speed of the material testing machine changes smoothly, and the maximum load variation per unit rotation angle during intermittent rotation is determined by the load detector. The resolution is smaller than that of .

Although the motor rotates intermittently during low-speed operation, the loading speed of the test piece changes smoothly due to the rigidity of the material testing machine and the inertia of the moving parts. Also, the maximum load variation per unit rotation angle during intermittent rotation.

Since it is smaller than the resolution of the load detector, the elongation-load characteristics recorded will not be a step-like curve but will be smooth.

F. Embodiment FIGS. 1(a) and 1(b) are schematic configuration diagrams of a material testing machine according to the present invention, and the same parts as in FIG. 4 are given the same reference numerals for explanation. The rotation of the motor 1 controlled by the motor control unit 10 is transmitted to the screw rod 32 via a drive gear train 38. The motor 1 is provided with an encoder 2, and a pulse signal having a frequency corresponding to the motor rotation speed is input from the encoder 2 to the motor control section 10. In addition, test piece 37
The elongation of is detected by an extensometer 15.

FIG. 1(b) shows the motor control unit 10, and the position controller 3 receives a pulse signal corresponding to the target load speed from the load speed setting unit 4 and a pulse signal corresponding to the actual motor rotation speed sent from the encoder 2. The pulse signals are input, and the frequency deviation between the two pulse signals is output as a voltage value. F/
The D converter 5 converts the pulse signal of the encoder 2 into a voltage value corresponding to its frequency, and inputs it to the deviation device 6 as a speed feedback signal. The voltage signal output from the position controller 3 is also input to this deviation device 6, the deviation of the surface input signal is taken, and the result is input to the next stage PWM motor drive circuit 7 as a motor control signal.

The PWM motor drive circuit 7 includes a deviation device 71, a comparator 72, a switching transistor 73, and a current transformer 7.
4, a rectifier 75, and an AC power source 76, and PWM control is performed by feeding back the detection signal of the current transformer 74 to the deviation device 71.

For example, the load speed is 0.05 to 1000m++/w
When in is set, the speed ratio becomes 1:20000. Now, during high-speed operation of 0,1 to 1000wn/win, the output shaft of motor 1 is made to rotate continuously by PWM control, and during low-speed operation of 0.05 to 0.1+na+/win, the output shaft of motor 1 is set to rotate continuously. Set the specifications of each device so that it rotates intermittently at a rotation angle corresponding to the set speed. The rigidity of the material testing machine was adjusted so that the loading speed of the test piece fluctuated smoothly even during intermittent rotation of the motor.
Appropriately determine the inertia of each moving part.

Figure 2 is a block diagram of the recording section, and the detection signal of the load cell 12 that detects the load applied to the test piece is transmitted by the amplifier
3 to the vertical axis drive terminal of the recorder 14.

A detection signal from an extensometer 15 that detects the elongation of the test piece is input to the horizontal axis drive terminal of the recorder 14 via an amplifier 16.

Figure 3 is a graph in which the horizontal axis is the motor rotation angle and the vertical axis is the load. It shows the output characteristics of the load cell 12 when rotated.

The one-dot chain line shows similar characteristics when the grip is included.

From FIG. 3, when the resolution of the load cell 12 is a load a, in order to deform the material testing machine so much that the load cell 12 in the no-load state outputs the load a, it is sufficient to rotate the motor 1 by the rotation angle. I understand that. Now, if the rotation resolution of the motor 1 is a rotation angle C that is larger than b, when the motor 1 is rotated by the rotation angle C, the load cell 12 may increase by 2a, and the load-elongation diagram of the recorder 13 will change in steps. This may occur.

Therefore, in the present invention, the rigidity of the material testing machine, the resolution of the load cell 12, and the resolution of the motor 1 are set as follows.

As shown in FIG. 3, when the resolution of the load cell 12 is a and the rigidity of the material testing machine is shown by the dashed line, the rotational resolution of the motor 1 is set to be d, which is smaller than b. As a result, even if the motor 1 rotates by the rotation angle d, the load actually applied to the test piece is less than the resolution of the load cell 12, so even if the output shaft of the motor 1 is intermittently driven, the display on the recorder will be in steps. There is no change in the shape, and smooth measurement is possible.

The operation of such an embodiment will be explained.

When a set speed is set from the speed setting section 4, a pulse signal that causes the output shaft of the motor 1 to continuously rotate is supplied to the motor 1 from the motor drive circuit 7.

The rotation speed of the motor 1 is detected by the encoder 2, and a pulse signal with a frequency proportional to the rotation speed is sent to the position controller 3.
The 0 position controller 3 that is input to the
A pulse signal with a frequency proportional to the set speed is also supplied from the deviator 6, and a signal corresponding to the frequency deviation of the surface input pulse is sent to the deviation device 6.
send to The pulse signal from the encoder 2 is converted into a voltage value by the F/V converter 5 and input to the deviation device 6. The deviation device 6 takes the deviation of the surface input, and the PWM motor drive circuit 7
input a signal corresponding to the deviation. The PWM motor drive circuit 7 is a well-known circuit, and supplies the motor 1 with a motor drive pulse signal having a duty ratio corresponding to the magnitude of the input voltage signal. The motor 1 is rotationally driven by this motor drive signal.

As described above, the output shaft of the motor 1 rotates intermittently during low-speed operation, but since the rigidity of the material testing machine and the inertia of the moving parts are appropriately determined, the loading speed of the test piece fluctuates smoothly.

Furthermore, since the load that varies with the maximum unit rotation angle during intermittent rotation is made smaller than the resolution of the load cell 12, the recorder 14 can obtain a continuous elongation-load characteristic diagram rather than a step-like one.

In addition, since PWM control is performed in this embodiment, a motor drive pulse signal is supplied to the motor 1 even during high-speed operation, but the output shaft does not rotate intermittently due to the inertia of the rotating part of the motor itself. Rotates smoothly and continuously.

In addition, two types of motor drive circuits are provided for high and low speeds, and the motor 1 is driven by PWM control at high speeds and voltage control without control, and the motor 1 is switched to be driven by pulses only at low speeds. You can.

G0 Effects of the Invention Since the present invention is constructed as described above, the motor can be controlled over a wide range without using a mechanical speed reducer, contributing to cost reduction. In addition, the noise and vibration generated from the reducer are completely eliminated, making it possible to provide a quiet material testing machine.

[Brief explanation of the drawing]

Figures 1 to 3 illustrate one embodiment of the present invention.
Figure 1 (a) is a front view of the material testing machine, Figure 1 (b) is a block diagram of its motor control section, Figure 2 is a wiring diagram of the load cell, extensometer, and recorder, and Figure 3 is the motor rotation. It is a graph showing the relationship between angle and load. FIG. 4 is a front view showing a conventional material testing machine. 1: Motor 2: Encoder 3: Position controller 4: Speed setting section 7: PWM motor drive circuit 3o: Material testing machine Patent applicant Shimadzu Corporation Patent attorney Representative Fuyu Nagai Figure 8

Claims (1)

[Claims] A motor for loading a test piece, a detection means for detecting a motor rotation speed, a motor drive circuit that supplies a motor drive signal to the motor based on a deviation between a target motor speed and the detected motor speed, and a test piece. The material testing machine is equipped with a load detector that detects the applied load, and the output shaft of the motor is rotated intermittently during low-speed operation. A materials testing machine, characterized in that the inertial force of the moving part of the testing machine is set so that the maximum variation in load per unit rotation angle during intermittent rotation is smaller than the resolution of the load detector.