JP2004212171A - Ram stroke detection apparatus and testing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stroke detection apparatus for overcoming various problems of a wire stroke detection apparatus such that (1) a wire is broken by a shock when a test specimen is broken, and (2) the stroke precision is degraded when a wire tension is relaxed and a pulley idles motion. <P>SOLUTION: A universal testing machine grips a test piece between upper and lower cross heads 36, 37. The cross head 36 elevates a table 34 vertically disposed by using a ram cylinder 62 and applies a load to the test piece. The ram stroke detection apparatus 50 for detecting a stroke of a ram 32a is provided with a magnetic scale 52 immovable regardless of elevation of the ram 32a and a pointer 54 for interlocking with movement of the table 34, noncontactly facing the magnetic scale 52 and changing a position relative to the magnetic scale 52. When the ram 32a moves, a stroke signal corresponding to a movement of the ram 32a is outputted from the magnetic scale 52. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stroke detection device for detecting a stroke amount of a load actuator used in a material testing machine.
[0002]
[Prior art]
The universal testing machine has an upper crosshead laid on a pair of columns erected on a table, and a lower crosshead screwed on a pair of screw rods erected through the table. The test specimen is grasped through a chuck in between, and the table is moved up and down by a ram cylinder to move the upper cross head in the vertical direction to apply a load to the test specimen. In such a tester, a ram stroke detecting device detects the stroke amount of the ram cylinder in order to perform a constant speed control test in which the ram cylinder strokes at a constant speed.
[0003]
As this type of ramstroke detecting device, there is known a device disclosed in Japanese Utility Model Publication No. 4-21091. This device has a wire fixed at one end to a table and the other end fixed to a holding member that moves up and down together with the table; a cushioning elastic body interposed at a connection point of the wire on the holding member side; It has a pulley around which a wire is wound and rotates with the movement of the wire, and a rotary encoder which detects the rotation of the pulley to detect a ram stroke.
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 4-21091
[Problems to be solved by the invention]
However, the conventional stroke detecting device has the following problems.
(1) The wire may break due to a shock when the specimen breaks.
(2) When the tension of the wire is loosened, the pulley idles and the accuracy of the stroke amount is reduced. Therefore, when testing a large number of specimens of the same shape under the same conditions, it is essential to reset the output value of the stroke meter at the start of the test every time.
(3) Detection accuracy depends on the outer diameter of the pulley.
(4) The wire diameter of the wire also affects the detection accuracy.
[0006]
SUMMARY OF THE INVENTION The present invention provides a stroke detecting device that solves the above-mentioned problem that is manifested by a wire type stroke detecting device.
The present invention also provides various testing machines equipped with the stroke detecting device.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is used in a test machine for gripping a specimen between upper and lower jigs, and lifting a table on which one jig is installed by a ram of a ram cylinder to load the specimen. The present invention is applied to a ramstroke detecting device for detecting a stroke amount of a ramstroke. The ram stroke detecting device comprises a first sensor member which is immovable with respect to the table regardless of the elevation of the ram and a first sensor member which is opposed to the first sensor member in non-contact with the movement of the table. A second sensor member whose relative position changes with respect to the first and second sensor members, and outputs a stroke signal corresponding to the amount of movement of the ram based on the change in the relative position of the first and second sensor members.
Such a ramstroke detecting device can be mounted on a universal testing machine or a compression testing machine for concrete or the like.
According to a fourth aspect of the present invention, there is provided a ramstroke detecting device according to the first aspect, a test automatic body changing machine for automatically changing a test object held by a jig, a test object is determined, and a detection signal of the ram stroke detecting device is provided. The jig is set to a position suitable for the specimen by controlling the position of the ram based on the ram, and the specimen is set between the jigs set in this way by the automatic body exchange machine and gripped by the jig Then, a controller is provided which repeats a series of procedures for loading the specimen held by the jig with the ram on specimens of different lengths.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
-1st Embodiment-
A first embodiment in which a material testing machine according to the present invention is applied to a universal testing machine will be described with reference to FIGS.
[0009]
1A and 1B show the configuration of a universal testing machine, wherein FIG. 1A is a front view and FIG. 1B is a sectional view taken along the line bb. A ram cylinder 32 is installed on the bed 31, and a pair of screw rods 33 are erected, and a pair of columns 35 are erected on a table 34 fixed to an end surface of the ram 32a. An upper crosshead 36 is provided on the upper ends of the pair of columns 35, and a lower crosshead 37 is screwed to the pair of screw rods 33 via a pair of nuts (not shown) provided therein. I have. The upper crosshead 36 can move up and down integrally with the table 34 and the column 35 by expansion and contraction of the ram cylinder 32, and the lower crosshead 37 can move up and down by rotation of the screw rod 33 or nut. An upper chuck 38 and a lower chuck 39 are attached to the upper and lower crossheads 36 and 37 so as to face each other, and both ends of the test piece TP are gripped by the upper and lower chucks 38 and 39, respectively.
[0010]
When the ram cylinder 32 supplies the pressurized oil to the cylinder chamber 32b, the ram 32a expands, whereby the table 34, the support 35, and the upper cross head 36 are integrally raised, and a load is applied to the test piece TP. The applied load is measured by detecting the pressure in the cylinder chamber 32b by the pressure sensor 40, and is, for example, digitally displayed. FIG. 3A shows a state in which the ram 32a is completely contracted and the load on the test piece TP is zero. At this time, a pressure corresponding to the weight of the table 34, the support 35, and the upper crosshead 36 acts on the cylinder chamber 32b, and the pressure sensor 40 outputs a predetermined pressure signal. At this time, the display unit displays zero. Adjust the zero point.
[0011]
A ramstroke detecting device 50 as shown in FIG. 2 is provided between the bed 31 and the table 34.
[0012]
In FIG. 2, a magnetic scale 52 is attached to a side surface of a stand 51 erected on the bed 31. On the other hand, a pointer mounting plate 53 is hung on the lower surface of the table 34 along the stand 51, and a pointer 54 is mounted on the tip thereof. When the pointer 54 moves up and down as the table 34 moves up and down, a stroke signal corresponding to the relative position between the pointer 54 and the magnetic scale 52 is output. This stroke signal is output to a control device (not shown), whereby the stroke amount of the ram 32a is detected. In FIG. 2, (a) shows the maximum extension state of the ram 32a, and (b) shows the minimum contraction state of the ram 32a.
[0013]
In performing a constant speed control test for raising the upper crosshead 36 at a constant speed, first, a pair of the screw rods 33 or a nut (not shown) in the lower crosshead 37 screwed to the screw rods 33 is rotated. The position of the lower crosshead 37 is adjusted, and both ends of the test piece TP are gripped by the upper and lower chucks (upper and lower jigs) 38 and 39 at that position. When pressurized oil is supplied to the ram cylinder 32 to cause the ram 32a to stroke at a constant speed, the ram 32a is extended, and the table 34, the support 35, and the upper crosshead 36 are integrally raised. Thereby, a tensile load acts on the test piece TP.
[0014]
At this time, the pointer mounting plate 53 suspended on the table 34 moves up and moves relative to the magnetic scale 52, and a stroke signal corresponding to the relative position is input to a control device (not shown). Thus, the stroke amount of the ram 32a is measured. The control device controls the amount of pressure oil supplied to the ram cylinder 32 based on the measurement result so that the ram 32a strokes at a constant speed.
[0015]
As described above, by detecting the stroke amount of the ram 32a by the non-contact magnetic stroke detection device 50, the following operation and effect can be obtained.
(1) The pointer 54 and the magnetic scale 52 are not in contact with each other, and there is no possibility that the pointer 54 and the magnetic scale 52 will be damaged even if the relative position is momentarily changed by a shock when the specimen breaks.
[0016]
(2) Even if the pointer 54 and the magnetic scale 52 change momentarily relative to each other when the specimen breaks, the relative position returns to the fracture when a predetermined time elapses, so that the position of the ram 32a at the time of fracture can be accurately measured.
[0017]
(3) Since the mounting position of the pointer 54 and the magnetic scale 52 does not shift due to the breakage of the specimen, if the table 34 is at the same position, the stroke detection signal is also the same. As a result, when a large number of specimens having the same shape are tested under the same conditions, the operation of resetting the output value of the stroke meter at the start of the test to zero every time is not required.
[0018]
(4) When a stroke detection device using a wire is used, a limit switch may be provided for detecting a specific position such as an initial position. According to this embodiment, a limit for detecting a specific position of the table 34 is used. No switch is required. Further, when another position detection such as a maximum stroke position is required in addition to the initial position, a number of limit switches corresponding to those positions are required. However, according to this embodiment, the stroke detection signal , Various positions of the table can be arbitrarily specified. As a result, the limit switch for detecting the specific position of the table 34 can be eliminated.
[0019]
-2nd Embodiment-
FIG. 3 is a configuration diagram of a compression tester for concrete, mortar, stone, or the like according to the second embodiment. A ram cylinder device 62 is installed on a lower base 61a of the load frame 61. A table 63 is provided at the upper end of the ram 62a of the ram cylinder device 62. A lower platen 64 is installed on the upper surface of the table 63, and an upper platen 65 is installed on the lower surface of the upper base 61 b of the load frame 51. A cylindrical concrete specimen CR is sandwiched between the upper and lower platens 64 and 65. The magnetic stroke detection device 50 described with reference to FIG. 2 is provided between the table 63 and the lower base 61a.
[0020]
In the compression test of the concrete specimen CR, the compression test is performed by raising the ram 62a with the upper platen 65 spaced apart from the upper surface of the specimen CR by several mm, for example, about 5 mm to 8 mm as an initial position. The compression speed is about 1 mm / 1 minute, and it takes about 5 to 8 minutes for the upper platen 65 to start contacting the specimen CR. The concrete specimen CR is standardized to have a diameter of 100 mm and a length of 200 mm, for example, but has a tolerance of ± several mm. For this reason, in the case of a specimen manufactured to be short, the interval between the specimen CR and the upper platen 65 is widened and the time until the start of compression becomes long. Therefore, it is necessary to reduce this interval and shorten the test time. Is done. Therefore, it is necessary to adjust the initial position of the table 63 for each specimen by ± several mm.
[0021]
For example, assume that the specimen CR has a maximum of 210 mm and a minimum of 190 mm. For example, the reference initial position of the table 63 when the specimen CR is set between the upper and lower platens 64 and 65 is determined for a maximum of 210 mm and set in a controller (not shown). At this time, it is assumed that a gap of 5 mm is set between the upper pressure plate 65 and the upper surface of the specimen CR. Prior to the test, the length of the specimen CR is measured in advance and input to a controller (not shown). Assuming that the measured value is 190 mm, the controller increases the reference initial position by 20 mm, which is the difference between the test sample maximum length 210 mm and the 190 mm that set the reference initial position. Then, the ram 62a is driven so that the detected value of the magnetic stroke device 50 becomes the reference position. That is, the ram 62a is extended by 20 mm. At this time, the interval is 5 mm. Thus, the initial position of the table 63 can be arbitrarily changed, and the compression test can always be started at a constant distance between the upper surface of the test piece and the upper platen even if the length of the test piece is different.
[0022]
-Third embodiment-
When the universal testing machine according to the first embodiment is used as an automatic testing machine, that is, when a method of automatically exchanging test pieces by a robot is adopted, tests are continuously performed on test pieces of various lengths. Do. In this case, the mounting position for gripping the test piece with the upper and lower jigs differs depending on the length of the test piece. Therefore, the controller previously sets the mounting position for each test piece, that is, the initial position of the ram 32a. In the processing algorithm of the continuous test, the specification of the test piece, the initial position of the ram for each test piece, the number of the specified test pieces, the test conditions including the test speed, the test order, and the like are described. In the following description, it is assumed that each of the first to m-th test piece groups has n test pieces, and the test piece lengths between the groups are different.
[0023]
The configuration of such an automatic machine is shown in FIG. 4, and the processing procedure is shown in the flowchart of FIG. In FIG. 4, the automatic machine mainly includes a controller 71, a ram stroke detecting device 50, a pressure sensor 40, a ram control valve 72, an automatic test piece exchange (robot) 73, and a vertical jig opening / closing device 74. Have. The ram control valve 72 is a hydraulic control valve that controls the expansion and contraction position of the ram 32a while detecting the ram position with the ram stroke detection device 50 so that the ram position is set to a preset ram position. The robot 73 is a transfer robot for holding the test piece and inserting and setting the upper and lower ends of the test piece between the upper and lower jigs 38 and 39. When the test piece is set between the upper and lower jigs by the robot 73, the grippers of the upper and lower jigs 38 and 39 are driven to open and close by the upper and lower jig opening and closing device 74. If the jigs 38 and 39 are pneumatic chucks, the opening / closing device 74 is a pneumatic opening / closing valve.
[0024]
When the controller 71 executes the automatic test program, the process shown in the flowchart of FIG. 5 is performed. When the start of the continuous test is instructed (step S1), the controller 71 determines the test piece (step S2), and reads the table initial position and the test condition for the determined test piece (step S3). Next, the table 34 is driven to the initial position (Step S4), the test piece is set between the upper and lower jigs by the robot 73, and the grippers of the upper and lower jigs 38 and 39 are driven by the upper and lower jig opening / closing device 74 to perform the test. The piece is gripped (step S5).
[0025]
The test piece is loaded by driving the ram 32a according to the test conditions (step S6). Step S7 is negative until the fracture of the test piece is detected, and step S6 is repeated. Then, when a break is detected (Yes in step S7), the ram 32a is stopped (step S8), and the test piece is removed by the robot 73 (step S9). Thereafter, if it is not determined that the tests of the n same test piece groups have been completed (No in Step S10), the process returns to Step S4. When it is determined that the test of n identical test piece groups is completed (Yes in step S10), it is determined whether the next test piece group exists (step S11), and if there is, the process returns to step S2. If not, the process of FIG. 4 ends.
[0026]
As described above, the stroke detection signal from the magnetic non-contact type stroke detection device 50 described above can correctly detect the position of the ram 32a. As a result, if initial positions for test pieces of various lengths are set in the controller in advance, the ram 32a is moved to a different test piece set position for each test piece without providing a plurality of limit switches for detecting the initial position. Can be positioned. Therefore, the universal material testing machine can be used as an automatic machine.
[0027]
When a conventional wire-type stroke detecting device is used, as described above, the pulley may undesirably idle when the test piece breaks, and the output signal of the rotary encoder accurately determines the telescopic position of the ram. Not necessarily shown. Therefore, in order to correctly position the ram at the test piece setting position, it is necessary to provide a limit switch for each test piece of various lengths. The test piece set, test, test piece removal, test piece set, test ... It was practically difficult to apply to repeated continuous automatic tests.
[0028]
In the above embodiment, the pointer 54 is moved together with the table 34. However, the pointer 54 may be immovable and the magnetic scale 52 may be moved together with the table 34. Further, in the above-described stroke detection device, the first sensor member is realized by the pointer 54 and the second sensor member is realized by the magnetic scale 52 using magnetism. However, a photoelectric non-contact stroke detection device using light is used. May be used. In this case, the light emitting element may be moved together with the table 34, and the light receiving element may be installed on a bracket fixed to the bed 31 side. The light receiving element may be moved together with the table 34 so that the light emitting element is immobile. In addition, as long as the first sensor member and the second sensor member constituting the stroke detecting device are not in contact with each other, any detection method may be used.
[0029]
【The invention's effect】
According to the present invention, since the stroke detection device is constituted by the first and second sensor members that are not in contact with each other, the relative position of the first and second sensor members even when an impact force due to, for example, test piece breakage acts. Does not change, the accuracy of the detection signal of the stroke detection device does not deteriorate. Therefore, if such a stroke detection device is mounted on a universal testing machine, it is not necessary to use a plurality of limit switches when performing continuous tests while automatically transporting test pieces of different lengths to the testing machine.
[Brief description of the drawings]
1 (a) is a front view of a universal testing machine, (b) is a sectional view taken along the line bb of FIG. 2 [FIG. 2] is a front view of a ramstroke detecting device [FIG. 3] is a front view of a concrete compression testing machine [ FIG. 4 is a diagram showing a configuration example of an automatic machine. FIG. 5 is a flowchart showing a processing procedure example.
31: bed 32: ram cylinder device 32a: ram 34: table 50: ram stroke detection device 52: magnetic scale 54: pointer 62: ram cylinder device 62a: ram 71: controller 73: robot s
TP: Test piece CR: Concrete test piece

Claims (4)

The specimen is held between the upper and lower jigs, and the table on which one of the jigs is installed is moved up and down by a ram of a ram cylinder to be used in a testing machine for loading the specimen. In a ramstroke detecting device for detecting,
A first sensor member that is immovable with respect to the table regardless of the elevation of the ram;
A second sensor member which, in conjunction with the movement of the table, faces the first sensor member in a non-contact manner and changes its relative position with respect to the first sensor member;
A ramstroke detecting device, which outputs a stroke signal according to a movement amount of the ram based on a relative position change of the first and second sensor members. A universal testing machine comprising the ramstroke detecting device according to claim 1. A compression tester comprising the ramstroke detection device according to claim 1. A ramstroke detection device according to claim 1,
A test automatic body changer that automatically changes the test specimen held by the jig,
The jig is set to a position suitable for the test piece by determining the test piece and controlling the position of the ram based on the detection signal of the ram stroke detecting device, and between the jigs thus set. The test specimen is set by the test automatic body exchange machine and gripped by a jig, and then, a series of steps of loading the test specimen gripped by the jig with the ram, for test specimens of different lengths. A universal automatic testing machine, comprising:

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