JP3134723U - Material testing machine - Google Patents

Abstract

A crosshead is prevented from dropping when a hydraulic clamp is released.
A crosshead 3 that moves up and down along a column 2, a load actuator 7 that loads a specimen TP between the crosshead 3 and a base 1, and a crosshead 3 that corresponds to the size of the specimen TP. The crosshead 3 is moved by the lifting cylinder 4, the fixing means 9 for fixing the crosshead 3 to the column 2 at an arbitrary height position, the command means 34 for instructing the release of the fixing means 9, and the fixing means 9. When the release of the fixing means 9 is instructed by the command means 34 in the fixed state, the release means 12, 23, 30 for releasing the fixing means 9 after replenishing the lifting cylinder 4 with a holding pressure corresponding to the leak, Is provided.
[Selection] Figure 3

Description

  The present invention relates to a material testing machine having a cross head that can be raised and lowered.

  Conventionally, the crosshead is moved up and down along the struts by expanding and contracting the lifting cylinder, the specimen is gripped by a pair of grips between the base and the crosshead, and a tensile test, a compression test, a bending test, and a fatigue test are performed. A material testing machine to perform is known (see, for example, Patent Document 1). In the material testing machine described in Patent Document 1, a hydraulic clamp is actuated by turning on a clamp switch during a test to fix the position of the crosshead. After the test is completed, the hydraulic clamp is released by turning on the unclamp switch, and the crosshead can be raised and lowered.

JP-A-8-304249

  By the way, in a material testing machine having this type of lifting cylinder, the pressure oil in the cylinder leaks to the outside as time elapses. Therefore, if the unlock switch is turned on after a long time has passed after the test is completed, the crosshead may drop undesirably by an amount corresponding to the leakage of the lifting cylinder.

The material testing machine according to the present invention includes a cross head that moves up and down along a column, a load actuator that loads the specimen between the cross head and the base, and an elevator that raises and lowers the cross head according to the size of the specimen. Cylinder, a fixing means for fixing the crosshead to the column at an arbitrary height position, a command means for instructing the release of the fixing means, and the fixing means When release is instructed, the release cylinder is provided with release means for releasing the fixing means after replenishing the lifting cylinder with a holding pressure corresponding to leakage.
When release of the fixing means is instructed by the command means, it is preferable to start replenishment of pressure oil to the elevating cylinder and to release the fixing means after a predetermined time has elapsed.
It has a control valve that switches according to the lift command and controls the action of the drive pressure on the lift cylinder. When the command means releases the fixing means, it corresponds to a leak in the lift cylinder by switching the control valve After the holding pressure is replenished, the fixing means can be released with the control valve switched to the neutral position.
The fixing means is configured as a hydraulic clamp that is operated by pressure oil from a hydraulic source, an operation check valve is provided in a pipeline that is supplied with operating pressure from the hydraulic source to the hydraulic clamp, and the release means is connected to the fixing means by the command means. When release is instructed, it may have a disabling means for disabling the function of the operation check valve as a check valve after replenishing the lifting cylinder with a holding pressure equivalent to a leak.

  According to the present invention, since the fixing of the crosshead is released after supplying the holding pressure corresponding to the leak to the hydraulic cylinder, it is possible to prevent the crosshead from dropping when the fixing of the crosshead is released.

Hereinafter, an embodiment of a material testing machine according to the present invention will be described with reference to FIGS.
FIG. 1 is a front view of a material testing machine according to an embodiment of the present invention. The material testing machine includes a pair of support columns 2 erected on the base 1, a cross head 3 that moves up and down along the support column 2, and a pair of lifts that move the cross head 3 up and down according to the size of the specimen TP. Cylinder 4, upper grip 5 and lower grip 6 for gripping specimen TP between base 1 and crosshead 3, load actuator 7 for loading specimen TP, and load applied to load actuator 7 And a hydraulic clamp 9 for fixing the crosshead 3 to the support column 2 at an arbitrary height position during the test.

  The load actuator 7 is a hydraulic cylinder driven by pressure oil from a hydraulic source, and a piston rod of the hydraulic cylinder passes through the cross head 3 and is connected to the upper grip 5. The upper grip 5 is driven by a hydraulic cylinder, a load is applied to the specimen TP, and a tensile test, a compression test, a bending test, and a fatigue test are performed. Alternatively, the load actuator 7 may be supported on the base 1 and the lower gripping tool 6 may be driven by the load actuator 7 to apply a load to the specimen TP. The load actuator 7 may be constituted by a pneumatic cylinder, an electromagnetic force type load actuator, or a linear motor type load actuator instead of a hydraulic cylinder.

  The elevating cylinder 4 is erected on the outside of the column 2 in parallel with the column 2. As shown in FIG. 2, the elevating cylinder 4 is a single-acting cylinder in which pressure oil is supplied and discharged from the bottom surface of the cylinder rod 4a, and the crosshead 3 is integrally fixed to the peripheral surface of the cylinder tube 4b. When pressure oil is supplied to the elevating cylinder 4, the elevating cylinder 4 expands and the crosshead 3 rises as shown in FIG. When the pressure oil is discharged from the lifting cylinder 4, the lifting cylinder 4 is retracted and the crosshead 3 is lowered as shown in FIG.

  In such a material testing machine, the hydraulic clamp 9 is operated during the test, and the crosshead 3 is fixed to the column 2. On the other hand, after the test is completed or when the length and size of the specimen TP are changed, the operation of the hydraulic clamp 9 is released to raise and lower the crosshead 3. At this time, if a long time elapses after the end of the test with the hydraulic clamp 9 being operated, the pressure oil in the elevating cylinder 4 leaks to the outside or leaks from the valve included in the pipe line. When the operation of the clamp 9 is released, the crosshead 3 may drop by gravity by an amount corresponding to the leak amount immediately after that. Therefore, in the present embodiment, the following configuration is used to prevent undesired drop of the crosshead 3 immediately after the hydraulic clamp 9 is released.

  FIG. 3 is a hydraulic circuit diagram showing a main configuration of the material testing machine according to the present embodiment, and shows a drive circuit for the lifting cylinder 4 and the hydraulic clamp 9. The flow of oil discharged from the hydraulic pump 11 is controlled by the electromagnetic switching valve 12, and the flow of oil discharged from the hydraulic pump 21 is controlled by the electromagnetic switching valves 22 and 23. The electromagnetic switching valves 12, 22 and 23 are switched by a control signal from the controller 30.

  The controller 30 includes a CPU, a ROM, a RAM, and other peripheral circuits. The controller 30 includes an ascending switch 31 that commands the raising of the crosshead 3, a descending switch 32 that commands the lowering, a clamp switch 33 that commands the operation of the hydraulic clamp 9, and an unclamp that commands the release of the hydraulic clamp 9. A switch 34 is connected.

  When the raising switch 31 is turned on, the electromagnetic switching valve 12 is switched to the position a. As a result, the pressure oil from the hydraulic pump 11 is supplied to the telescopic cylinder 4 via the operation check valve 13 and the slow return valve 14, and the telescopic cylinder 4 expands. In this case, although the pressure according to the set pressure of the relief valve 16 acts on the expansion / contraction cylinder 4, the relief valve 16 is relieved so that the pressure of the expansion / contraction cylinder 4 becomes a pressure sufficient to raise the crosshead 3. Pressure is set. When the raising switch 31 is turned off, the electromagnetic switching valve 12 is switched to the neutral position, and the extension operation of the telescopic cylinder 4 is stopped.

  When the lowering switch 32 is turned on, the electromagnetic switching valve 12 is switched to the position b. As a result, the pressure oil from the hydraulic pump 11 is guided into the pipe line 15, and the pilot pressure in the pipe line 15 acts on the operation check valve 13. As a result, the operation check valve 13 becomes an open valve, and the oil in the expansion cylinder is returned to the tank by the dead weight of the crosshead 3, and the expansion cylinder 4 is degenerated. When the lowering switch 32 is turned off, the electromagnetic switching valve 12 is switched to the neutral position, and the retracting operation of the telescopic cylinder 4 is stopped.

  On the other hand, when the clamp switch 33 is turned on, the electromagnetic switching valve 22 is switched to the position b. As a result, the pressure oil from the hydraulic pump 21 passes through the electromagnetic switching valve 22 and acts on the hydraulic clamp 9 via the operation check valve 24, the hydraulic clamp 9 is activated, and the crosshead 3 is fixed to the column 2. The When the clamp switch 33 is turned off, the electromagnetic switching valve 22 is switched to the position A, and the action of pressure oil from the hydraulic pump 21 to the hydraulic clamp 9 is stopped. In this state, since the pressure oil continues to act on the hydraulic clamp 9 by the check valve 24, the operation of the hydraulic clamp 9 can be maintained.

  When the unclamp switch 34 is turned on, the electromagnetic switching valve 23 is switched to the position B by a process described later. As a result, the pressure oil from the hydraulic pump 21 acts on the pilot port of the operation check valve 24, the operation check valve 24 becomes an open valve, and the tank pressure acts on the hydraulic clamp 9. As a result, the operation of the hydraulic clamp 9 is released, and the crosshead 3 can be raised and lowered.

  Processing in the controller 30 when the unclamp switch 34 is turned on will be described. FIG. 4 is a flowchart illustrating an example of processing executed by the controller 30. The process shown in this flowchart is started, for example, by turning on the power switch of the testing machine. In step S1, it is determined whether or not the unclamp switch 34 is turned on. If step S1 is affirmed, the process proceeds to step S2, and the electromagnetic switching valve 12 is switched to position a.

  Next, in step S3, a timer is started, and in step S4, it is determined whether or not the timer has counted a predetermined time ta (for example, 5 seconds). If step S4 is affirmed, the process proceeds to step S5, and the electromagnetic switching valve 12 is switched to the neutral position. In step S6, the electromagnetic switching valve 23 is switched to the position B, and the process ends.

  According to the above processing, when the unclamp switch 34 is turned on, the electromagnetic switching valve 12 is switched to the position A, and the pressure oil from the hydraulic pump 11 is supplied to the elevating cylinder 4. As a result, the oil for the leak is replenished to the elevating cylinder 4 and a holding pressure for holding the crosshead 3 acts in the elevating cylinder.

  When a predetermined time ta elapses after the unclamp switch 34 is turned on, the electromagnetic switching valve 12 is switched to the neutral position and the electromagnetic switching valve 23 is switched to the position B. As a result, tank pressure acts on the hydraulic clamp 9 and the operation of the hydraulic clamp 9 is released. At this time, the oil corresponding to the leak is replenished to the telescopic cylinder 4 in advance, and a sufficient holding pressure is applied to hold the crosshead 3, so that the crosshead 3 is dropped when the hydraulic clamp 9 is released. Can be prevented.

  When the raising switch 31 and the lowering switch 32 are operated in a state where the hydraulic clamp 9 is released, the electromagnetic switching valve 12 is switched to the position A or position B according to the operation, and the crosshead 3 is moved up and down. When the clamp switch 33 is further operated, the electromagnetic switching valve 22 is switched to the position B, and the hydraulic clamp 9 is activated.

According to the above embodiment, the following effects can be obtained.
(1) When the clamp release command is issued, the hydraulic clamp 9 is released by switching the electromagnetic switching valve 23 after the electromagnetic switching valve 12 is switched to replenish the lift cylinder 4 with oil corresponding to the leak. Undesirable dropping of the crosshead 3 when the unclamp switch 34 is on can be prevented.
(2) Since the hydraulic clamp 9 is released after a lapse of a predetermined time ta after switching the electromagnetic switching valve 12, a sufficient holding pressure can be supplied to the elevating cylinder 4 and the configuration is simple.
(3) Since the operation check valve 24 is provided between the electromagnetic switching valve 22 and the hydraulic clamp 9 and the function of the operation check valve 24 as a check valve is invalidated, the hydraulic clamp 9 is released. Above preferred.
(4) Since the holding pressure is supplied to the elevating cylinder 4 by switching the electromagnetic switching valve 12, it is not necessary to add a new part to supply the holding pressure, and it can be configured at low cost.

  In the above embodiment, the cross head 3 is moved up and down by driving the lifting cylinder 4, but the configuration of the lifting cylinder is not limited thereto. For example, the elevating cylinder may be a pneumatic cylinder instead of a hydraulic cylinder. Although the crosshead 3 is fixed to the support column 2 by the hydraulic clamp 9, the fixing means is not limited to this. The release of the hydraulic clamp 9 is commanded by operating the unclamp switch 34, but the command means is not limited to this.

  After a predetermined time has elapsed since the unclamp switch 34 was turned on, the electromagnetic switching valve 23 was switched by a signal from the controller 30 to release the hydraulic clamp 9, but after the holding pressure corresponding to the leak was supplied to the elevating cylinder 4 As long as the hydraulic clamp 9 is released, the release means may have any configuration. The same processing as in the controller 30 may be performed by hardware using a relay circuit having a timer relay. Although the function of the operation check valve 24 as the check valve is invalidated by switching the electromagnetic switching valve 23, other invalidating means may be used.

  Although a pair of raising / lowering cylinder 4 was provided in the outer side of a pair of support | pillar 2, the structure of a material testing machine is not restricted to this. That is, as long as the features and functions of the present invention can be realized, the present invention is not limited to the material testing machine of the embodiment.

The front view of the material testing machine which concerns on embodiment of this invention. The figure which shows the expansion-contraction operation | movement of the raising / lowering cylinder of FIG. The hydraulic circuit diagram which shows the principal part structure of the material testing machine which concerns on this Embodiment. 4 is a flowchart showing an example of processing executed by the controller of FIG. 3.

Explanation of symbols

3 Crosshead 4 Lifting cylinder 7 Load actuator 9 Hydraulic clamp 12, 22, 23 Electromagnetic switching valve 24 Operate check valve 30 Controller 34 Unclamp switch

Claims (4)

A crosshead that moves up and down along the column;
A load actuator for loading a specimen between the crosshead and the base;
An elevating cylinder for elevating the crosshead according to the size of the specimen;
Fixing means for fixing the crosshead to the support column at an arbitrary height position;
Command means for commanding release of the fixing means;
When release of the fixing means is instructed by the command means in a state where the crosshead is fixed by the fixing means, the holding means equivalent to leak is supplied to the lifting cylinder and then the fixing means is released. A material testing machine comprising: release means. The material testing machine according to claim 1,
When the release means is instructed to be released by the command means, the release means starts supplying pressure oil to the lifting cylinder and releases the fix means after a predetermined time has elapsed. Material testing machine. The material testing machine according to claim 1 or 2,
A control valve that switches according to an elevation command and controls the action of the drive pressure on the elevation cylinder;
When the release means is instructed to be released by the command means, the release means replenishes the elevating cylinder with a holding pressure equivalent to a leak by switching the control valve, and then switches the control valve to the neutral position. A material testing machine, wherein the fixing means is released in a state. In the material testing machine according to any one of claims 1 to 3,
The fixing means is a hydraulic clamp that is operated by pressure oil from a hydraulic source,
An operation check valve is provided in a pipeline through which an operating pressure is supplied from the hydraulic source to the hydraulic clamp,
When the release means is instructed to be released by the command means, the release means disables the function of the operation check valve as a check valve after replenishing the lifting cylinder with a holding pressure corresponding to a leak. A material testing machine characterized by comprising a crystallization means.

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