JP2010180913A - Single rod double-acting cylinder and testing machine - Google Patents

Abstract

Provided is a single rod return cylinder in which thrusts at the time of retraction and expansion are made equal without requiring pressure control.
[Solution]
The piston rod 120 is formed with an in-rod pressure chamber C <b> 1, and an outer rod pressure chamber C <b> 2 is formed around the piston rod 120. In the cylinder tube 110, a fixed plunger 140 protrudes toward the piston rod 120 and is fitted in the rod pressure chamber C1.
When working fluid such as pressure is introduced into the pressure chamber C1 within the rod and is pressurized, pressure acts on the pressure receiving surface S1 of the pressure chamber C1 within the rod, and the piston rod 120 expands. On the other hand, when the working fluid is introduced into the rod outer pressure chamber C2 and pressurized, pressure acts on the pressure receiving surface S2 of the rod outer pressure chamber C2, and the piston rod 120 is contracted. Since the areas F1 and F2 of the pressure receiving surfaces S1 and S2 are set to be equal, the thrust during the expansion operation of the piston rod 112 is equal to the thrust during the contraction operation.
[Selection] Figure 1

Description

  The present invention relates to a single rod double acting cylinder and a testing machine equipped with a single rod double acting cylinder.

  A single rod double acting cylinder performs a contracting operation by introducing working fluid into the rod chamber around the piston rod, and performs an extending operation by introducing working fluid into the bottom chamber on the piston bottom surface side. In comparison, there is an advantage that the total length is short.

  When the single rod double acting cylinder is applied to a material testing machine, a durability testing machine, a fatigue testing machine, etc. (for example, see Patent Document 1) that repeatedly applies a load to the specimen, the testing machine can be configured compactly.

JP-A-6-345392

Conventionally, since the pressure receiving area of the rod chamber and the pressure receiving area of the bottom chamber are different in the single rod double acting cylinder, if the working fluid pressure is made constant, the thrust at the time of degeneracy and extension will be different and the thrust cannot be equalized . Therefore, in order to make the thrusts equal, the working fluid pressure at the time of retraction and extension must be changed.
In other words, the conventional single rod double acting cylinder requires a pressure control circuit for equalizing the thrust force when retracting and when extending, and its configuration and operation are complicated.

  In the testing machine described in Patent Document 1, the rod chamber and bottom chamber of a single rod double-acting cylinder are connected to a hydraulic source or a tank via servo valves, respectively, and the pressure oil is supplied to the rod chamber and bottom chamber by switching the servo valves. Conduct fatigue tests with controlled supply. In this case, the capacity of the load cell is determined based on the maximum thrust (driving force) when the cylinder is retracted.

  However, since the rod chamber has a smaller pressure receiving area than the bottom chamber and the maximum thrust when the cylinder is retracted is smaller than the maximum thrust when the cylinder is extended, for example, if the servo valve fails during cylinder extension, the capacity of the load cell There is a risk of generating a thrust (driving force) exceeding.

A single rod double acting cylinder according to the present invention has a cylinder tube having a first end and a second end, and penetrates the first end of the cylinder tube in a sealing and slidable manner. A piston rod provided with a space for the pressure chamber in the rod that opens toward the portion, and provided at the end of the piston rod inside the cylinder tube, and in sliding contact with the inner surface of the cylinder tube in a sealing manner, A piston that forms a rod external pressure chamber around the piston rod between the first ends, and projects from the second end toward the piston rod in the cylinder tube, and for the rod internal pressure chamber A fixed plunger that is inserted in the space in a sealing and slidable manner to form a pressure chamber in the rod, a first supply passage that supplies a working fluid to the pressure chamber in the rod, and the lock And a second supply path for supplying working fluid to outside the pressure chamber, the pressure receiving area of the rod outer pressure chamber, characterized in that equal to the pressure receiving area of the rod in the pressure chamber.
The second supply path may be formed to pass through the fixed plunger, or may be formed to pass through the piston rod.

  The testing machine according to the present invention includes the single rod double acting cylinder, a servo valve that controls supply of the working fluid from the working fluid source to the first supply passage and the second supply passage, and the single rod double acting cylinder. A detecting means for detecting any one of a test force applied to the specimen through the test piece and a displacement of the specimen, and a control means for driving and controlling the servo valve according to a detection result of the detecting means. To do.

The single rod double acting cylinder according to the present invention can equalize the thrust when the piston rod retracts and the thrust when the piston rod extends without requiring pressure control.
The testing machine according to the present invention can equalize the thrust at the time of piston rod retracting and the thrust at the time of piston rod extension without requiring pressure control, and can further prevent damage due to a servo valve failure or the like.

BRIEF DESCRIPTION OF THE DRAWINGS The longitudinal cross-sectional view which shows 1st Embodiment of the single rod double acting cylinder which concerns on this invention. The longitudinal cross-sectional view which shows 2nd Embodiment of the single rod double acting cylinder which concerns on this invention. The front view which shows the testing machine to which the single rod double acting cylinder of FIG. 1 is applied.

-First embodiment-
A first embodiment of a single rod double acting cylinder according to the present invention will be described below with reference to FIG.

  In FIG. 1, a single rod double acting cylinder 100 includes a cylinder tube 110, a piston rod 120 penetrating through an end portion (referred to as a “first end portion”) 110A of the cylinder tube 110 in a sealing manner, and a cylinder. A piston 130 is provided at the end of the piston rod 120 in the tube 110 and sealably slidably contacts the inner surface of the cylinder tube 110.

  The piston rod 120 is formed with a pressure chamber space C1 in the rod so as to open toward the other end portion (referred to as “second end portion”) 110B of the cylinder tube 110. On the other hand, The rod external pressure chamber C2 is formed between the piston 130 and the first end portion 110A.

  A fixed plunger 140 projects from the second end 110 </ b> B toward the piston rod 120 in the cylinder tube 110. The fixed plunger 140 is fitted into the space for the pressure chamber in the rod in a sealing and slidable manner, thereby forming a pressure chamber C1 in the rod in the piston rod 120 as will be described later.

  In the figure, 122 and 124 are sealing members such as an oil seal, packing, and O-ring that seal the gap between the outer periphery of the piston rod 120 and the inner surface of the cylinder first end portion 110 </ b> A, and 132, 134, and 136 are pistons of the piston 130. A similar sealing member 144 for sealing the gap between the outer periphery and the inner periphery of the cylinder tube 110 is a similar sealing member for sealing the gap between the outer periphery of the fixed plunger 140 and the inner surface of the rod internal pressure chamber C1.

  The fixed plunger 140 is inserted into a through-hole 118 formed in the second end portion 110B, and the tip is inserted into a space for the rod pressure chamber in the piston 120 to form a rod pressure chamber C1. A flange 146 is provided at the end of the fixed plunger 140 on the second end 110B side. The fixed plunger 140 is fixed to the cylinder tube 110 by fixing the flange 146 to the second end 110B with a bolt 148 or the like.

  When working fluid such as pressure is introduced into the pressure chamber C1 within the rod and pressurized, the bottom surface on the first end 110A side of the rod pressure chamber C1 becomes the pressure receiving surface S1 for the driving pressure, while the rod When the working fluid is introduced into the external pressure chamber C2 and pressurized, the surface on the second end 110B side of the rod external pressure chamber C2 becomes the pressure receiving surface S2 for driving pressure.

  When the pressure chamber C1 in the rod is pressurized by the working fluid, the piston rod 120 is pushed out in the direction of the first end portion 110A, and the cylinder 100 performs an extending operation. That is, the piston rod 120 extends from the cylinder tube 110. On the other hand, when the pressure chamber C2 outside the rod is pressurized by the working fluid, the piston rod 120 is pulled in the direction of the second end portion 110B, and the cylinder 100 is retracted. That is, the piston rod 120 is retracted to the cylinder tube 110.

That is, the pressure receiving surface S1 is a driving pressure receiving surface when the cylinder is extended, and the pressure receiving surface S2 is a driving pressure receiving surface when the cylinder is retracted. When the cylinder tube 110, the piston rod 120, and the fixed plunger 140 are circular in cross section, the inner diameter of the cylinder tube 11 is D1, the outer diameter of the piston rod 120 is D2, and the outer diameter of the fixed plunger 140 is D3.
The areas F1 and F2 of the surfaces S1 and S2 are
^{F1 = π (D3) 2/} 4 Equation (1)
F2 = π {(D1) ² − (D2) ² } / 4 Formula (2)
And, in effect,
F1 = F2 Formula (3)
The dimensions of D1, D2, and D3 are set so that That is,
(D3) ² = (D1) ^2- (D2) Formula ² (4)
It is.

  By setting the pressure receiving area as described above, the thrust during the cylinder retracting operation and the thrust during the cylinder extending operation can be made equal without requiring pressure control. In the testing machine, by making the thrust at the time of contraction and extension equal, the test force exceeding the capacity of the load cell 700 is not applied, the load cell 700 or hydraulic parts are damaged, the specimen TP Damage can be prevented.

  The cylinder tube 110 is provided with a port 112 communicating with the rod external pressure chamber C2 and a port 114 communicating with the bottom chamber C3 on the second end 110B side in the cylinder tube 110. Further, the fixed plunger 140 is provided with a working fluid path 142 communicating with the in-rod pressure chamber C1, and the cylinder tube 110 is provided with a port 116 communicating with the working fluid path 142.

  The ports 112 and 116 are connected to the servo valve 200, and a pump 210 and a tank 220 are connected to the servo valve 200. By the switching operation of the servo valve 200, the working fluid is supplied to the rod internal pressure chamber C1 and the rod external pressure chamber C2 through the first supply passage FP1 and the second supply passage FP2, and the rod internal pressure chamber C1, rod The working fluid is discharged from the external pressure chamber C2.

  The first supply path FP1 passes from the port 116 through the working fluid path 142 in the fixed plunger 140 to reach the rod pressure chamber C1. The port 114 is connected to the tank 220, and the leaked working fluid is discharged according to the change in the capacity of the bottom chamber C3. A relief valve 230 is connected to the pipe line from the pump 210 to the servo valve 200, and the upper limit pressure of the pipe line is regulated by discharging the working fluid having a predetermined pressure or higher to the tank 220, thereby preventing the servo system from being damaged. ing.

  The servo valve 200 is a three-position switching valve that is switched by a signal from the controller 300. In the neutral position in FIG. 1, the rod internal pressure chamber C1 and the rod external pressure chamber C2 are blocked from the pump 210 and the tank.

  When the servo valve 200 is switched to the A position, the rod internal pressure chamber C1 communicates with the pump 210, and the rod external pressure chamber C2 communicates with the tank 220. As a result, the cylinder 100 is extended. On the other hand, when the servo valve 200 is switched to the low position, the pressure chamber C1 in the rod communicates with the tank 220 and the pressure chamber C2 outside the rod communicates with the pump 210. As a result, the cylinder 100 is degenerated.

  Note that as the working fluid of the single rod double acting cylinder 100, pressurized oil, pressurized air, and other various fluids can be employed.

[testing machine]
In FIG. 3, in the testing machine 500 to which the single rod double acting cylinder 100 of the first embodiment is applied, the single rod double acting cylinder 100 is attached to the lower surface of the table 610 supported by the base 600.

  A pair of support columns 620 are erected on the upper surface of the table 610, and a cross head 630 is supported on the support columns 620 by a hydraulic cylinder (not shown) so as to be movable up and down. The base 600, the table 610, the column 620, and the cross head 630 constitute a reaction force frame that bears a reaction force of a load applied to the specimen TP.

  An upper grip 800 is attached to the crosshead 630 via a load cell 700, and the upper end of the specimen TP is gripped by the upper grip 800. A lower grip 820 is provided below the upper grip 800, and the lower end of the specimen TP is gripped by the lower grip 820.

  In the single rod double acting cylinder 100, the piston rod 120 can extend and contract in the vertical direction while passing through the table 610, and a lower grip 820 is fixed to the upper end portion of the piston rod 120.

When the single rod double acting cylinder 100 is controlled by the servo valve 200 and expanded and contracted, the lower gripping tool 820 moves up and down, and a test force is applied to the specimen TP.
Unlike the double rod cylinder, the single rod double acting cylinder 100 does not project a piston rod on the lower end surface of the piston 130, so that the overall length is short and the testing machine can be configured compactly.

  The driving amount of the single rod double acting cylinder 100 is detected by a displacement sensor 900. In the displacement sensor 900, for example, a magnet (not shown) is provided around a probe (not shown) that generates a magnetostrictive line, and the probe moves in a non-contact manner along the magnet, thereby generating a torsional strain on the magnetostrictive line. This is a known magnetostrictive linear displacement sensor that measures the position of the magnet by measuring the propagation time of the strain. The magnet is fixed to movable parts such as the piston rod 120 and the piston 130 so as to surround the probe.

  In FIG. 3, the displacement sensor 900 is provided on the lower end surface of the single rod double acting cylinder 100 for convenience of explanation, but in actuality, it is installed at an appropriate location along the above-described configuration. Moreover, the format of the displacement sensor 900 is not limited to the above.

  The test force signal detected by the load cell 700 and the displacement signal detected by the displacement sensor 900 are input to the controller 300, and the controller 300 controls the servo valve 200 based on these input signals, and the one-rod double-acting cylinder 100. Control the drive.

When performing a fatigue test using a testing machine, the servo valve is adjusted so that the single rod double-acting cylinder 100 is expanded and contracted at a predetermined cycle, a load is repeatedly applied to the specimen TP, and the output of the load cell 700 becomes a constant sine wave. 200 is feedback-controlled.
-Second Embodiment-

  Hereinafter, a second embodiment of a single rod double acting cylinder according to the present invention will be described with reference to FIG. In the figure, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the second embodiment, the first supply path FP1 is formed so as not to pass through the fixed plunger 140 but to pass through the piston rod 120.

  In FIG. 2, a working fluid path 126 extending from the in-rod pressure chamber C <b> 1 toward the first end 110 </ b> A and extending to the outside of the cylinder tube 110 is drilled in the piston rod 120 along the axial center of the piston rod 120. Furthermore, the piston rod 120 is formed with a port 128 communicating with the working fluid path 126 on the side surface outside the cylinder tube 110.

  The first supply path FP1 passes from the port 128 through the working fluid path 126 to reach the rod pressure chamber C1.

  That is, the first supply path FP1 may pass through either the fixed plunger 140 or the piston rod 120.

According to the present embodiment, the following operational effects can be achieved.
(1) By making the pressure receiving area of the pressure chamber C1 in the rod equal to the pressure receiving area of the pressure chamber C2 outside the rod, the thrust at the time of degeneration and extension can be made uniform without controlling the pressure.
(2) In the testing machine 500 to which the single-rod double-acting cylinder 100 is applied, it is possible to equalize the thrust at the time of retraction and expansion without controlling the pressure, and further prevent damage due to the failure of the servo valve 200, etc. Can do.

(3) The single rod double acting cylinder 100 according to the present invention can be reduced in size as compared with the reverse acting cylinder, but without hindering the downsizing and without complicating the circuit and the configuration. That is, the thrust during the piston extending operation and the retracting operation can be made equal without increasing the cost.

  In the above-described embodiment, the example in which the cylinder 100 is configured as a vertical tester that expands and contracts in the vertical direction has been described. However, the cylinder 100 may be configured as a horizontal tester. It can also be used as a vibration tester for durability tests that does not have a reaction force frame. Further, the single rod return cylinder according to the present invention can be used in various devices other than the above-described testing machine. Further, the areas F1 and F2 of the pressure receiving surfaces S1 and S2 are made equal to make both thrusts during the cylinder extension operation and the cylinder retraction operation equal, but within the range allowed by the equipment or device in which the single rod return cylinder is used. If so, it is within the technical scope of the present invention that the two thrusts do not match. In other words, as long as the features and functions of the present invention can be realized, the present invention is not limited to the single rod return cylinder according to the embodiment and the testing machine using the cylinder.

C1 Rod inner pressure chamber C2 Rod outer pressure chamber FP1 First supply path FP2 Second supply path S1, S2 Pressure receiving surface 100 Single rod double acting cylinder 110 Cylinder tube 110A First end 110B Second end 120 Piston rod 130 Piston 140 Fixed plunger

Claims (4)

A cylinder tube having a first end and a second end;
A piston rod that penetrates the first end of the cylinder tube in a sealing and slidable manner, and that is provided with a space for the pressure chamber in the rod that opens toward the second end;
A piston that is provided at an end of a piston rod in the cylinder tube and forms a rod external pressure chamber around the piston rod between the first ends by sealingly slidingly contacting the inner surface of the cylinder tube; ,
A fixed portion that protrudes from the second end toward the piston rod inside the cylinder tube and is fitted in the pressure chamber space in the rod in a sealing and slidable manner to form a pressure chamber in the rod. A plunger,
A first supply path for supplying a working fluid to the pressure chamber in the rod;
A second supply path for supplying a working fluid to the pressure chamber outside the rod,
A single rod double acting cylinder, wherein the pressure receiving area of the rod outer pressure chamber is equal to the pressure receiving area of the rod inner pressure chamber. In the single rod double acting cylinder according to claim 1,
The single rod double acting cylinder, wherein the first supply path is formed to pass through the fixed plunger. In the single rod double acting cylinder according to claim 1,
The one-rod double acting cylinder, wherein the first supply path is formed to pass through the piston rod. The single rod double acting cylinder according to any one of claims 1 to 3,
A servo valve for controlling the supply of the working fluid from the working fluid source to the first supply path and the second supply path;
Detecting means for detecting either the test force applied to the specimen via the single rod double acting cylinder or the displacement of the specimen;
And a control unit that drives and controls the servo valve according to a detection result of the detection unit.

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