JP2000298084A - Material tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate possibility getting hurt by an air chuck at a time of the attachment and detachment of a test piece and possibility performing an erroneous test caused by the insufficiency of grasping force without performing troublesome operation for adjusting grasping force. SOLUTION: The air pressure driving actuators 2a, 2b for grasping a test piece W is controlled by the signal outputted from a tester controller 3 in synchronous relation to the start/stop of a test not only to increase grasping force automatically at the start time of a test but also to weaken the grasping force automatically in synchronous relation to the completion of the test. By this constitution, the setting of the grasping force of the air chucks 2a, 2b by manual operation is dispensed with and the generation possibility of an operation mistake is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a material testing machine,
More specifically, the present invention relates to a material testing machine of a type for performing a tensile test by gripping a test piece with an air chuck.

[0002]

2. Description of the Related Art In a material testing machine for performing a tensile test of a test piece, generally, a pair of upper and lower chucks (grasping tools) is used to hold the both ends of the test piece and a pair of chucks is relatively moved by a driving mechanism. By separating
A tensile load is applied to the test piece. In such a material testing machine, there is known a device provided with an air chuck as a chuck for gripping a test piece. In a material testing machine using an air chuck, the air chuck is normally configured to be opened and closed by operating a switch, lever, or foot-operated switch. This is done by letting

When performing a tensile test on a test piece using a material testing machine, it is natural that an accurate test cannot be performed if the gripping position of the test piece by the chuck is moved. The force requires a considerably large force to withstand the tensile load and not move the test piece. When attaching or detaching the test piece by opening and closing the air chuck, if the air chuck is immediately tightened with such a large force by operating a switch or the like, the switch or the like may be erroneously operated, or the gripper may be erroneously moved to the holding position by the chuck. If you close the air chuck while touching it, you may be seriously injured.

Conventionally, in a material testing machine using an air chuck, a switch or lever for manual operation for selecting the gripping force of the air chuck between two levels, strong and weak, is provided. Providing a stepped switch,
By operating the switches and the like by the operator,
Measures are taken to reduce the gripping force when attaching and detaching the test piece and to increase the gripping force before starting the test.

[0005]

However, the setting of the gripping force of the air chuck by the operation of the operator as described above is not only troublesome because it is a manual or stepping operation, and there is a possibility that the operation may be forgotten. In some cases, a normal test cannot be performed by starting a test with a low gripping force, or a test piece may be attached or detached with a high gripping force.

The present invention has been made in view of such circumstances, and eliminates the possibility of injury due to an air chuck when attaching and detaching a test piece without performing troublesome operations, and also prevents erroneous operation due to insufficient gripping force. The aim is to provide a material testing machine that does not have the possibility of conducting a test.

[0007]

In order to achieve the above object, the material testing machines of the present invention are arranged to face each other,
A pair of air chucks each of which is opened and closed by a switch operation, a drive mechanism for relatively approaching / separating the pair of air chucks, and a controller for driving and controlling the drive mechanism. In a material testing machine for performing a tensile test of a test piece by separating the pair of air chucks while holding the pair of air chucks, high and low pressures are applied to apply two types of strong / weak gripping force to each of the air chucks. An air circuit for selectively supplying air is provided, and the controller outputs signals at the start and end of the tensile test to control the air circuit, and supplies air to each air chuck in synchronization with the start of the test. Switching the pressure from low pressure to high pressure, and switching the air pressure supplied to each air chuck from high pressure to low pressure in synchronization with the end of the test Thus characterized.

According to the present invention, an air circuit capable of selecting a gripping force of an air chuck in synchronization with a drive start / stop signal using a controller which supplies a drive start / stop signal to a drive mechanism of a material testing machine. The purpose of the present invention is to achieve the intended purpose by automatically changing the gripping force of the air chuck by supplying a control signal to the air chuck.

That is, the drive mechanism starts or stops driving according to a signal supplied from the controller, thereby starting / stopping the tensile test. A control signal is supplied to an air circuit capable of switching the gripping force of the air chuck between two levels, strong and weak, in synchronization with a drive start / stop command of the drive mechanism by the controller, and the air chuck is synchronized with the start of the test. By automatically increasing the gripping force of the air chuck and automatically weakening the gripping force of the air chuck in synchronization with the end of the test, without the need for operation by the operator,
When the test piece is attached or detached, the gripping force of the air chuck automatically decreases, and during the test, the gripping force automatically increases.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an overall configuration of an embodiment of the present invention. Testing machine body 1
Is a bed 11, two screw rods 12a, 12b rotatably supported by the bed 2, and each screw rod 12a, 12b.
A cross yoke 13 for rotatably holding the upper end of the screw rod b, a driving mechanism 14 for rotating and driving the screw rods 12a and 12b, a cross head 15 supported on the screw rods 12a and 12b via nuts, and the like. The crosshead 15 is configured to move up and down by rotating the screw rods 12a and 12b by driving of the driving mechanism 14.

An upper air chuck 2a is mounted on the lower surface of the crosshead 15, and a lower air chuck 2b is mounted on the upper surface of the bed 11 so as to face the upper air chuck 2a. In the tensile test of the test piece W, the driving mechanism 14 is driven to drive the screw rods 2a, 2b in a state where both ends are gripped by the upper air chuck 2a and the lower air chuck 2b.
Is rotated to raise the cross head 15, thereby separating the upper air chuck 2a from the lower air chuck 2b. Drive mechanism 14
Is controlled by a signal supplied from a test machine controller 3 disposed adjacent to the test machine main body 1, and by operating a start switch 31 provided on the test machine controller 3, the cross head 15 is raised to perform a tensile test. At the same time as when the test piece W breaks during the test, or when the test piece W reaches a specified elongation or the tensile load acting on the test piece W reaches a specified value, etc. When the condition is satisfied, the crosshead 15 is automatically stopped to terminate the tensile test.

Each of the air chucks 2a and 2b is driven by a built-in air cylinder to hold the gripping members 21a and 22b.
a, 21b, and 22b have a known structure that opens and closes and grips the test piece W.
Operation switches 41a and 41b for opening and closing 2b
Is mounted. The air chuck operation circuit unit 4 is an electric circuit unit that supplies a drive control signal to the air unit 5 that drives the air chucks 2a and 2b to open and close at a required pressure, and operates by operating the operation switches 41a and 41b. It operates also by the control signal supplied from the test machine controller 3.

FIG. 2 shows a circuit diagram of the air unit 5. Air is supplied to air cylinders 23a and 23b that open and close the air chucks 2a and 2b via chuck opening and closing solenoid valves 51a and 51b, respectively. Each of the chuck opening / closing solenoid valves 51a and 51b is provided with an operation switch 4
The drive is controlled by the operations of 1a and 41b. The input ports of the chuck opening / closing solenoid valves 51a and 51b are supplied with high-pressure air from the high-pressure air source 53 or low-pressure air obtained by reducing the high-pressure air by the pressure-reducing valve 54 by driving the pressure changing solenoid valve 52. Either is selectively supplied. The pressure changing solenoid valve 52 is driven and controlled by a control signal supplied from the test machine controller 3 via the air operation circuit unit 4. The testing machine controller 3 outputs a control signal to the pressure changing solenoid valve 52 in synchronization with the start and end of the tensile test, and sets the control signal to the high pressure side at the start of the test and to the low pressure side at the end of the test.

FIG. 3 is a flowchart showing the operation procedure of the above embodiment of the present invention. For the tensile test,
Low pressure air is supplied to the input ports of the chuck opening / closing solenoid valves 51a and 51b. In this state, the test piece W is set on the upper and lower air chucks 2a and 2b, and the operation switches 41a and 41b are manually operated. Thus, both ends of the test piece W are gripped by the air chucks 2a and 2b.

Next, when the start switch 31 of the testing machine controller 3 is operated to instruct the start of the tensile test, a control signal for the pressure changing solenoid valve 52 is immediately output from the testing machine controller 3 and each chuck opening / closing electromagnetic valve is opened. Valve 5
High pressure air is supplied to the input ports 1a and 51b. Thereby, the gripping force of each of the air chucks 2a and 2b automatically increases. After outputting the above control signal to the pressure changing solenoid valve 52, the test machine controller 3 applies high pressure air to the air cylinders 23a, 23 of the air chucks 2a, 2b.
b after a certain period of time set in advance in consideration of the time required for reliable supply to the drive mechanism 1
Drive 4 to start the tensile test. Eventually, when the above-described test end conditions such as breakage of the test piece W are satisfied, the test machine controller 3 supplies a stop command to the drive mechanism 14 to end the test, and controls the pressure changing solenoid valve 52. A signal is output to each of the chuck opening / closing solenoid valves 51a,
Supply low pressure air to the input port of 51b. Thus, the gripping force of each of the air chucks 2a and 2b automatically decreases. In this state, the test piece W is removed by manually operating the operation switches 41a and 41b.

According to such a procedure, when the operator mounts and removes the test piece W, each air chuck 2a,
The gripping force of 2b is weak, so that there is no danger of injuries even if a finger or the like is pinched between the air chucks 2a or 2b by performing erroneous operations, and the operator does not perform any operation. Since the gripping force of the air chucks 2a and 2b is increased, the test may be started with a low gripping force due to an operation error as in the related art, and an accurate test may not be performed, or the test piece W may fall off. No problems occur.

In the above embodiment, the air circuit using the pressure changing solenoid valve 52 and the pressure reducing valve 54 is used to change the gripping force of the air chucks 2a and 2b. The high-pressure air from 53 is supplied to a remote control type pressure reducing valve capable of controlling the pressure by an electric signal, and a pressure control signal is supplied to the pressure reducing valve in synchronization with the start / stop of the test as described above. It is also possible to adopt a configuration in which

[0018]

As described above, according to the present invention, the gripping force of the air chuck, which is opened and closed by manual operation and grips the test piece, is output from the controller of the material testing machine in synchronization with the start of the tensile test. And automatically weakened by a signal output from the controller in synchronization with the end of the tensile test. Because there is no risk of injury when a finger or the like is caught in the air chuck, and the gripping force of the air chuck is automatically increased during the actual tensile test without any operation by the operator after mounting the test piece. In addition, there is no danger that the test will be performed with a low gripping force due to forgetting the operation as in the related art.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of an air unit 5 according to the embodiment of the present invention.

FIG. 3 is a flowchart showing an operation procedure when performing a tensile test according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Test machine main body 11 Bed 12a, 12b Screw rod 14 Cross head 15 Drive mechanism 2a, 2b Air chuck 23a, 23b Air cylinder 3 Test machine controller 31 Start switch 4 Air chuck operation circuit unit 41a, 41b Operation switch 5 Air unit 51a, 51b Solenoid valve for opening and closing chuck 52 Solenoid valve for changing pressure 53 High pressure air source 54 Pressure reducing valve

Claims (1)

[Claims] 1. A pair of air chucks, which are arranged to face each other and are opened and closed by a switch operation, a driving mechanism for relatively approaching / separating the pair of air chucks, and a controller for driving and controlling the driving mechanism. A material testing machine for performing a tensile test of a test piece by separating the pair of air chucks while holding both ends of the test piece by the air chucks, wherein the strength / weakness of each of the air chucks is 2 An air circuit for selectively supplying high-pressure / low-pressure air to impart a certain gripping force, and the controller outputs signals at the start and end of the tensile test to control the air circuit, The air pressure supplied to each air chuck is switched from low pressure to high pressure in synchronization with the start, and supplied to each air chuck in synchronization with the end of the test. Material testing machine, characterized in that switching the air pressure from the high pressure to low pressure.