JP6622498B2 - Fluid pressure cylinder - Google Patents

Description

  The present invention relates to a fluid pressure cylinder.

  Patent Document 1 discloses a hydraulic cylinder that includes a piston having a recess formed with a female thread portion that meshes with a male thread portion of a piston rod, and that has a hexagonal head formed on the opposite side of the piston recess. In the hydraulic cylinder of Patent Document 1, using the hexagonal head, screw the male thread part of the piston rod into the female thread part of the piston recess until the end face of the piston rod comes into contact with the bottom of the piston recess, and push the piston to the specified torque. By tightening, the piston is fastened to the piston rod.

JP 2000-283117 A

  In the fluid pressure cylinder disclosed in Patent Document 1, a hexagon head is formed on the piston in order to fasten the piston and the piston rod with a predetermined tightening torque. Therefore, the total length of the piston is increased, and the fluid pressure cylinder is enlarged. To do.

  The present invention has been made in view of the above problems, and an object thereof is to reduce the size of a fluid pressure cylinder.

  In the first invention, since the fastening hole is formed in an arc shape, the fastening jig formed corresponding to the shape of the fastening hole has high rigidity against the force acting in the circumferential direction. Therefore, when the piston is fastened to the piston rod, a high tightening torque is transmitted to the piston by applying a large circumferential force to the fastening jig. Thus, since the piston can be fastened to the piston rod with a high tightening torque without forming a hexagonal head on the piston, the total length of the piston can be shortened.

1st invention is a fluid pressure cylinder, Comprising: The piston rod which a male thread part is formed in the front-end | tip, and is inserted in a cylinder tube, It is threaded | engaged with a male thread part, is connected with a piston rod, and follows the inner peripheral surface of a cylinder tube. Each of the pistons has a fastening hole into which a fastening jig is inserted when the piston is fastened to the piston rod, and the fastening hole has an arc shape extending in the circumferential direction. It is formed in this.

According to 1st invention, a fastening jig | tool can be inserted in the fastening hole of the both end surfaces of a piston, respectively, and a higher fastening torque can be transmitted to a piston.

The second invention is characterized in that a plurality of fastening holes are provided at equal intervals in the circumferential direction.

According to the second invention, the piston can be easily rotated by a plurality of fastening jigs and screwed into the piston rod.

  According to the present invention, the fluid pressure cylinder can be reduced in size.

It is sectional drawing of the fluid pressure cylinder which concerns on embodiment of this invention. It is a top view of the piston of the fluid pressure cylinder concerning the embodiment of the present invention. It is sectional drawing which shows the comparative example of the fluid pressure cylinder which concerns on embodiment of this invention.

  Hereinafter, a fluid pressure cylinder according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, a case where the fluid pressure cylinder is the hydraulic cylinder 100 that drives the hydraulic oil as the hydraulic fluid will be described.

  As shown in FIG. 1, the hydraulic cylinder 100 includes a piston rod 10 having an annular step portion 13 formed on the outer peripheral surface, a cylindrical cylinder tube 20 into which the piston rod 10 is inserted, and a tip of the piston rod 10. And a piston 30 that slides along the inner peripheral surface of the cylinder tube 20.

  The inside of the cylinder tube 20 is partitioned into a rod side chamber 1 and an anti-rod side chamber 2 by a piston 30. The hydraulic cylinder 100 is expanded and contracted by hydraulic pressure guided from the hydraulic source (working fluid pressure source) to the rod side chamber 1 or the anti-rod side chamber 2. A seal member 40 seals between the inner periphery of the cylinder tube 20 and the outer periphery of the piston 30. Thereby, the communication between the rod side chamber 1 and the anti-rod side chamber 2 between the inner periphery of the cylinder tube 20 and the outer periphery of the piston 30 is blocked.

  The piston rod 10 is formed between a main body portion 11 slidably supported by the cylinder tube 20, a small diameter portion 12 having an outer diameter smaller than that of the main body portion 11, and the main body portion 11 and the small diameter portion 12. An annular stepped portion 13 and a male threaded portion 14 that is formed in the small diameter portion 12 at the tip of the piston rod 10 and into which the piston 30 is screwed. The male screw portion 14 is provided at the tip of the small diameter portion 12 so as to be separated from the step portion 13 in the axial direction.

  The piston 30 includes a seating portion 31 that sits on the stepped portion 13 of the piston rod 10 and a female screw portion 32 that is screwed into the male screw portion 14 of the piston rod 10.

  The inner diameter of the piston 30 is formed smaller than the outer diameter of the main body portion 11 of the piston rod 10. Therefore, a part of the inside of the one end face 30 </ b> A of the piston 30 abuts on the step portion 13 of the piston rod 10 as the seating portion 31. The piston 30 is fastened to the piston rod 10 by being tightened with a predetermined tightening torque while the seating portion 31 is seated on the stepped portion 13 of the piston rod 10. As a result, the gap between the seat portion 31 and the stepped portion 13 is closed, so that the communication between the rod side chamber 1 and the anti-rod side chamber 2 between the outer periphery of the piston rod 10 and the inner periphery of the piston 30 is blocked. Is done.

  As shown in FIGS. 1 and 2, the piston 30 is formed with two fastening holes 35 on the end surface (end surface facing the non-rod side chamber 2) 30 </ b> B of the piston rod 10. The fastening holes 35 are each formed in an arc shape extending in the circumferential direction, and are provided at positions facing each other across the central axis.

  When the piston 30 is fastened, a fastening jig (not shown) formed in a shape corresponding to the shape of the fastening hole 35 is inserted into the fastening hole 35. The fastening device (not shown) grips the fastening jig and rotates the piston 30 around the central axis, thereby screwing the piston 30 into the piston rod 10. When the seating portion 31 of the piston 30 and the stepped portion 13 of the piston rod 10 abut, the fastening device rotates the piston 30 until a predetermined tightening torque is reached, and the piston 30 is fastened to the piston rod 10 by the predetermined tightening torque. To do.

  Since the fastening hole 35 is formed in an arc shape extending in the circumferential direction, the fastening jig having a shape corresponding to the fastening hole 35 has high rigidity against a force acting in the circumferential direction. Thus, since a fastening jig with high circumferential rigidity can be inserted into the fastening hole 35, a large circumferential force can be applied to the fastening jig, and a high fastening torque can be transmitted to the piston 30. . Thus, since a high tightening torque can be transmitted to the piston 30 through the fastening hole 35 formed in the piston 30, it is not necessary to form a hexagon head in the piston 30 in order to transmit the tightening torque. Therefore, the overall length of the piston 30 can be shortened.

  Moreover, since a high tightening torque can be transmitted to the piston 30, the piston rod 10 and the piston 30 can be fastened with an appropriate tightening torque according to the screw diameter. Therefore, loosening due to insufficient tightening torque is prevented. Therefore, the impact generated at the stroke end of the hydraulic cylinder 100 is prevented from acting intensively on the threads of the male screw portion 14 and the female screw portion 32 due to loosening, and the durability of the fastened piston rod 10 and piston 30 is ensured. be able to.

  Further, since a high tightening torque can be transmitted to the piston 30, the gap between the step portion 13 of the piston rod 10 and the seating portion 31 of the piston 30 can be reliably closed.

  Here, in order to facilitate understanding of the hydraulic cylinder 100, a hydraulic cylinder 200 as a comparative example will be described with reference to FIG. The same configuration as that of the hydraulic cylinder 100 will be described using the same reference numerals.

  In the hydraulic cylinder 200, as shown in FIG. 3, the female thread portion 132 is formed continuously from the one end face 30 </ b> A of the piston 130. Therefore, in the hydraulic cylinder 200, the axial position (hereinafter referred to as “contact position”) P <b> 1 of the contact portion where the stepped portion 13 of the piston rod 10 and the seating portion 31 of the piston 130 are in contact, and the male screw portion 14. The axial position (hereinafter referred to as “screwing position”) P <b> 2 of the screwed portion where the female screw portion 132 is screwed substantially coincides. For this reason, even if the piston 30 is fastened to the piston rod 10, the axial distance between the contact position P1 and the screwing position P2 is short, and the length of the piston rod 10 pulled in the axial direction is insufficient. It is difficult to generate axial force.

  On the other hand, in the hydraulic cylinder 100, the female thread portion 32 of the piston 30 is formed away from the seat portion 31 in the axial direction. A cylindrical surface 33 on which no screw is formed is formed between the one end surface 30A of the piston 30 including the seating portion 31 and the female screw portion 32. Therefore, the threaded portion where the male threaded portion 14 of the piston rod 10 and the female threaded portion 32 of the piston 30 are threaded together is axially extending from the abutting portion where the stepped portion 13 of the piston rod 10 and the seating portion 31 of the piston 30 abut. Are spaced apart from each other.

  Since the female thread portion 32 of the piston 30 is formed away from the seat portion 31, the contact position P1 and the screwing position P2 are separated in the axial direction as shown in FIG. Is provided. That is, the length of the piston rod 10 pulled in the axial direction by the tightening torque is increased. Therefore, when the piston 30 is fastened to the piston rod 10 in this state, the piston rod 10 between the contact position P1 and the screwing position P2 is pulled in the axial direction by the tightening torque, and the piston rod 10 and the piston 30 are separated from each other. High axial force can be generated. Therefore, the sealing performance between the seating portion 31 of the piston 30 and the stepped portion 13 of the piston rod 10 can be further improved, and the communication between the rod side chamber and the anti-rod side chamber through the inside of the piston rod 10 is more reliably performed. Is prevented.

  When an axial force that can transmit a high tightening torque to the piston 30 and secure the sealing performance between the seating portion 31 and the stepped portion 13 is generated, the female thread portion 32 of the piston 30 is fixed to the seating portion 31. It may be formed continuously from the seating portion 31 without being limited to being formed away from the seat. In other words, in this case, the cylindrical surface 33 may not be provided.

  However, even if the fastening hole 35 is formed in an arc shape, if the internal thread portion 32 of the piston 30 is provided continuously from the seat portion 31 and the length of the piston rod 10 pulled in the axial direction is insufficient, When the hydraulic oil is at a high pressure, there is a possibility that the space between the seat portion 31 and the step portion 13 cannot be closed. On the other hand, when the fastening hole 35 is formed in a shape in which only a fastening jig having low rigidity in the circumferential direction can be inserted even when the female thread portion 32 of the piston 30 is provided away from the seating portion 31. Cannot transmit a high tightening torque to the piston 30. Therefore, also in this case, there is a possibility that a sufficient axial force cannot be generated between the piston 30 and the piston rod 10.

  On the other hand, the piston 30 has both the internal thread part 32 provided apart from the seating part 31, and the fastening hole 35 formed in circular arc shape. Therefore, in the hydraulic cylinder 100, a high tightening torque can be transmitted to the piston 30, and a sufficient axial force can be generated by pulling the piston rod 10 in the axial direction by the transmitted tightening torque. Therefore, even when the hydraulic cylinder 100 is extended and contracted by the high-pressure hydraulic oil, the gap between the seating portion 31 of the piston 30 and the stepped portion 13 of the piston rod 10 can be reliably closed. Communication with the non-rod side chamber 2 can be more reliably blocked.

  Next, a modification of this embodiment will be described.

  In the above embodiment, the fastening hole 35 is formed in the other end surface 30 </ b> B of the piston 30 on the tip end side of the piston rod 10. Instead of this, a fastening hole 35 may be formed on one end face (the end face facing the rod side chamber 1) 30A including the seat portion 31. In this case, the fastening hole 35 may be provided at a position other than the seat portion 31.

  Further, the fastening hole 35 may be provided on each of both end faces 30A, 30B of the piston 30. In this case, since the sum of the cross-sectional areas of the inserted fastening jigs increases, a larger fastening torque can be transmitted.

  In the above embodiment, the two fastening holes 35 are provided in the piston 30. Instead of this, three or more fastening holes 35 may be provided in the piston 30. In this case, in order to easily rotate the piston 30, it is desirable that the fastening holes 35 are provided at equal angular intervals in the circumferential direction. Further, in order to easily rotate the piston 30, it is desirable that the piston 30 is provided with a plurality of fastening holes 35 into which the fastening jig is inserted, but the piston 30 is provided with a single fastening hole 35. Also good.

  In the above-described embodiment, the piston rod 10 is provided with the male screw portion 14 spaced from the stepped portion 13 and provided at the tip of the small diameter portion 12, and the piston 30 is provided with the female screw portion 32 spaced from the seating portion 31. Thereby, the screwing portion is separated from the contact portion. Not only this but the external thread part 14 of the piston rod 10 and the internal thread part 32 of the piston 30 may be formed in arbitrary structures. For example, the male screw portion 14 is separated from the stepped portion 13, while the inner periphery of the piston 30 is entirely formed as the female screw portion 32, and the cylindrical surface 33 may not be provided on the piston 30. Further, the female screw portion 32 may be separated from the seating portion 31, while all of the small diameter portion 12 of the piston rod 10 may be formed as the male screw portion 14. In addition, when a sufficiently high axial force can be generated to ensure sealing performance, the screwing portion and the contact portion do not have to be separated from each other.

  According to the above embodiment, there exist the effects shown below.

  In the hydraulic cylinder 100, since the fastening hole 35 is formed in an arc shape, the fastening jig formed corresponding to the shape of the fastening hole 35 has high rigidity against the force acting in the circumferential direction. Therefore, a high tightening torque can be transmitted to the piston 30 through the fastening hole 35 formed in the piston 30. For this reason, it is not necessary to form a hexagon head on the piston 30 in order to transmit the tightening torque. Therefore, the overall length of the piston 30 can be shortened, and the hydraulic cylinder 100 can be reduced in size.

  Further, since the female thread portion 32 of the piston 30 is formed away from the seat portion 31 in the axial direction, the length of the piston rod 10 that is pulled in the axial direction when the piston 30 and the piston rod 10 are fastened is sufficiently large. Can be secured. Therefore, a high axial force can be generated between the piston 30 and the piston rod 10. For this reason, even if the hydraulic fluid supplied to the hydraulic cylinder 100 is high pressure, the gap between the seating portion 31 of the piston 30 and the stepped portion 13 of the piston rod 10 can be reliably closed to exhibit high sealing performance. it can. Therefore, the communication between the rod side chamber 1 and the anti-rod side chamber 2 between the outer periphery of the piston rod 10 and the inner periphery of the piston 30 can be more reliably prevented.

  Hereinafter, the configuration, operation, and effect of the embodiment of the present invention will be described together.

  The hydraulic cylinder 100 includes a cylinder tube 20, a piston rod 10 having a male threaded portion 14 formed at the tip thereof and inserted into the cylinder tube, and screwed into the male threaded portion 14 and coupled to the piston rod 10, and an inner peripheral surface of the cylinder tube 20. And at least one end face (end face 30B) of the piston 30 is provided with a fastening hole 35 into which a fastening jig is inserted when the piston 30 is fastened to the piston rod 10. The fastening hole 35 is formed in an arc shape extending in the circumferential direction.

  In this configuration, since the fastening hole 35 is formed in an arc shape, the fastening jig formed corresponding to the shape of the fastening hole 35 has high rigidity against the force acting in the circumferential direction. Therefore, when the piston 30 is fastened to the piston rod 10, a high tightening torque is transmitted to the piston 30 by applying a large circumferential force to the fastening jig. Thus, since the piston 30 can be fastened to the piston rod 10 with a high tightening torque without forming a hexagon head on the piston 30, the overall length of the piston 30 can be shortened. Therefore, the hydraulic cylinder 100 can be reduced in size.

  Further, the hydraulic cylinder 100 is provided with a plurality of fastening holes 35 at equal intervals in the circumferential direction.

  According to this configuration, the piston 30 can be easily rotated by the plurality of fastening jigs and can be screwed into the piston rod 10.

  Further, the hydraulic cylinder 100 is provided with fastening holes 35 on both end faces 30 </ b> A and 30 </ b> B of the piston 30.

  According to this configuration, it is possible to transmit a higher tightening torque to the piston 30 by inserting the fastening jigs into the fastening holes 35 on both end faces of the piston 30.

  Further, the hydraulic cylinder 100 has a seat portion 31 where the piston 30 is seated on the step portion 13 formed on the outer peripheral surface of the piston rod 10, and the piston rod 10 is attached to the piston rod 10 with the seat portion 31 seated on the step portion 13. It is concluded.

  In this configuration, since the piston 30 is fastened to the piston rod 10 with a high tightening torque in a state where the seat portion 31 and the step portion 13 are seated, the gap between the seat portion 31 and the step portion 13 is reliably closed. It is. Therefore, high sealing performance can be exhibited between the piston 30 and the piston rod 10.

  Further, the hydraulic cylinder 100 has a female screw portion 32 in which the piston 30 is screwed into the male screw portion 14 of the piston rod 10, and the screwed portion in which the male screw portion 14 and the female screw portion 32 are screwed is the stepped portion 13. It is spaced apart in the axial direction from the contact portion with which the seat portion 31 contacts.

  In this configuration, since the contact portion and the screwing portion are separated in the axial direction, the length of the piston rod 10 pulled by the tightening torque becomes long.

  According to this configuration, a higher axial force can be generated, and the sealing performance between the piston 30 and the piston rod 10 can be further improved.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  DESCRIPTION OF SYMBOLS 100 ... Hydraulic cylinder (fluid pressure cylinder), 10 ... Piston rod, 13 ... Step part, 14 ... Male thread part, 20 ... Cylinder tube, 30 ... Piston, 30A ... End face, 30B ... End face, 31 ... Seating part, 32 ... Female thread 35, fastening hole

Claims (2)

A cylinder tube;
A piston rod formed with a male thread at the tip and inserted into the cylinder tube;
A piston that is screwed into the male thread portion and connected to the piston rod and sliding along the inner peripheral surface of the cylinder tube,
Each of both end faces of the piston is provided with a fastening hole into which a fastening jig is inserted when the piston is fastened to the piston rod.
The fluid pressure cylinder, wherein the fastening hole is formed in an arc shape extending in a circumferential direction. The fluid pressure cylinder according to claim 1, wherein a plurality of the fastening holes are provided at equal intervals in the circumferential direction .

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