JP5072710B2 - Piston coupling structure - Google Patents

Description

  The present invention relates to a piston coupling structure provided in a fluid pressure actuator such as a hydraulic cylinder.

  Conventionally, as this kind of piston coupling structure, there is one shown in FIG. 7 (see Patent Document 1).

  Explaining this, the piston 50 is fastened to the piston rod 30 via a nut 90.

  The piston rod 30 includes an annular step portion 48 with which the end surface of the piston 50 abuts, a piston mounting shaft portion 32 into which the inner periphery of the piston 50 is fitted, and a screw portion 49 into which the nut 45 is screwed.

  The piston 50 is sandwiched between the annular step portion 48 and the nut 90 and is configured to apply a predetermined axial force to the piston 50 by adjusting the tightening force of the nut 90 when the piston 50 is assembled.

Further, Patent Documents 2 to 4 each disclose a structure in which a ring-shaped member attached to an end portion of a piston rod is provided and the piston is coupled through the ring-shaped member.
JP 11-336894 A Japanese Utility Model Publication No. 60-59866 Japanese Utility Model Publication No. 5-3731 Japanese Utility Model Publication No. 1-77166

  However, in the conventional piston coupling structure shown in FIG. 7, the piston rod 30 is reduced in diameter in two stages by the piston mounting shaft portion 32 and the screw portion 49. There was a problem that the strength decreased.

  In addition, there is a problem that a lot of machining is performed on the piston rod 30 and the cost of the product is increased.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a piston coupling structure in which the diameter reduction of the piston mounting shaft portion can be minimized.

  The present invention includes a piston rod for driving a load, a cylindrical piston to which hydraulic pressure is guided, a piston locking means for locking displacement of the piston in the central direction of the piston rod with respect to the piston rod, and a piston with respect to the piston rod. A piston coupling structure comprising: a first and second helical slide ring in which a ring width in the direction of the center axis of the piston rod changes according to a relative rotational position; A second spiral slide ring locking means for locking the displacement of the two spiral slide ring in the axial direction of the piston rod, and adjusting the relative rotational position of the first and second spiral slide rings when the piston is assembled. It was set as the structure which provides predetermined | prescribed axial force to.

  According to the present invention, the piston rod can be formed with the same outer diameter at the portion where the piston is fitted and the portion where the first and second spiral slide rings are fitted, and the piston mounting shaft portion can be reduced in diameter. Minimized to improve piston rod strength. That is, the piston rod does not reduce the diameter of the piston rod between the piston and the first and second spiral slide rings unlike the conventional threaded portion, and avoids a decrease in the strength of the piston rod at this portion. In addition, the durability of the piston rod is ensured. And the cutting process given to a piston rod is reduced, and the cost of a product is aimed at.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a hydraulic cylinder 1 as a fluid pressure actuator. As shown in FIG. 1, the hydraulic cylinder 1 is configured such that the piston rod 30 moves in the direction of the central axis O with respect to the cylinder tube 10 by the hydraulic pressure guided from a hydraulic source (not shown). For example, when the hydraulic cylinder 1 drives a boom of a crane (not shown), the end 19 of the cylinder tube 10 is connected to the crane body (swivel base), and the end 39 of the piston rod 30 is connected to the boom.

  The cylinder tube 10 has a bottomed cylindrical shape, and a cylinder head 40 is fastened to the open end of the cylinder tube 10 via a plurality of bolts 43. The outer peripheral surface 31 of the piston rod 30 is slidably supported on the inner peripheral surface 12 of the cylinder tube 10.

  A piston 50 is connected to the piston rod 30 via piston fastening means 60 described later. The outer periphery of the piston 50 is slidably supported on the inner peripheral surface 12 of the cylinder tube 10.

  A pair of bearings 52 and a seal ring 53 are interposed on the outer periphery of the piston 50, and these are in sliding contact with the inner peripheral surface 12 of the cylinder tube 10.

  The inside of the cylinder tube 10 is defined by the piston 50 into two oil chambers 2 and 3. The oil chamber 2 communicates with a hydraulic pressure source via a rod side supply / discharge port 41 formed in the cylinder head 40 and a pipe (not shown) connected to the rod side supply / discharge port 41. The oil chamber 3 is communicated with a hydraulic pressure source via an end side supply / discharge port 21 formed in the cylinder tube 10 and a pipe (not shown) connected to the end side supply / discharge port 21.

  In the hydraulic cylinder 1, when the hydraulic pressure higher than that of the rod side supply / discharge port 41 is guided to the end side supply / discharge port 21 from the contracted state shown in FIG. 1, the piston 50 moves rightward in FIG. . On the contrary, when the hydraulic pressure higher than that of the end side supply / discharge port 21 is guided to the rod side supply / discharge port 41 from the extended state, the piston 50 moves leftward in FIG.

  Cylindrical bushes 4 and 5 are attached to the piston rod 30 with a piston 50 interposed therebetween, and the piston 50 and the piston rod 30 collide with the cylinder head 40 and the cylinder tube 10 when the hydraulic cylinder 1 is extended by the bushes 4 and 5. The impact to be eased. More specifically, when the bush 4 is inserted into the cushion port 42 of the cylinder head 40 near the stroke end during the extension operation of the hydraulic cylinder 1, a throttle oil passage is defined between them. The oil passage gives resistance to the flow of hydraulic oil from the oil chamber 2 toward the rod side supply / discharge port 41, and the speed at which the piston 50 suddenly collides with the cylinder head 40 is reduced. On the other hand, when the bushing 5 is inserted into the cushion port 29 of the cylinder tube 10 near the stroke end as shown in FIG. 1 during the contraction operation of the hydraulic cylinder 1, a throttle oil passage is defined between them. The throttle oil passage imparts resistance to the flow of hydraulic oil from the oil chamber 3 toward the end-side supply / discharge port 21 and reduces the speed at which the piston 50 suddenly collides with the bottom of the cylinder tube 10.

  FIG. 2A is an enlarged cross-sectional view of a portion showing the coupling structure of the piston 50 in the hydraulic cylinder 1 shown in FIG. As shown in FIG. 2A, the piston rod 30 has an outer peripheral surface 31 having an outer diameter D1, a piston mounting shaft portion 32 having an outer diameter D2 that is smaller than the outer peripheral surface 31, and the piston mounting shaft portion 32. A bush mounting shaft portion 33 having a further reduced diameter is formed.

  As a piston locking means 65 that locks the piston 50 with respect to the piston rod 30, an annular groove 34 is formed on the outer periphery of the piston mounting shaft portion 32, and a C-shaped ring 61 is fitted into the annular groove 34.

  The cylindrical bush 4 and the piston 50 are fitted and attached to the outer peripheral surface of the piston mounting shaft portion 32, and a ring 61 is interposed therebetween.

  The bush 4 is interposed between the annular end portion 35 of the piston rod 30 and the ring 61, and the clamping load of the piston fastening means 60 that fastens the piston 50 to the piston rod 30 does not act on the bush 4.

  A seal ring 7 is interposed between the bush 4 and the piston mounting shaft portion 32, and this portion is oil-tight.

  An annular recess 51 is formed at the inner peripheral end of the piston 50, and the annular recess 51 is fitted to the ring 61. As a result, the piston 50 is locked to the displacement in the left direction by the ring 61 with respect to the piston rod 30 in FIGS. Further, when the annular recess 51 is fitted to the outer periphery of the ring 61, it is locked that the ring 61 is enlarged in diameter and detached from the annular groove 34.

  As the piston fastening means 60 for fastening the piston 50 to the piston rod 30, first and second spiral slide rings 70 and 80 in which the ring width L in the direction of the piston rod central axis O changes depending on the relative rotational position, and the second spiral slide ring And a second spiral slide ring locking means 64 that locks the displacement of the 80 piston rod in the central axis O direction, and adjusts the relative rotational positions of the first and second spiral slide rings 70 and 80 when the piston 50 is assembled. Thus, a predetermined axial force is applied to the piston 50.

  The first and second spiral slide rings 70 and 80 are each formed in a cylindrical shape, and are fitted side by side with the piston mounting shaft portion 32.

  In the first and second spiral slide rings 70 and 80, spiral slide surfaces 71 and 81 facing each other are formed in a spiral shape with the piston rod central axis O as the center, and the piston rod central axis O depends on the relative rotational position of both. The ring width in the direction changes.

  FIG. 3 is a perspective view of the second spiral slide ring 80. As shown in FIG. 3, the second spiral slide ring 80 is formed so that the spiral slide surface 81 makes a round about the piston rod central axis O, and between the both ends of the spiral slide surface 81. A step 82 is formed.

  Similar to the second spiral slide ring 80, the first spiral slide ring 70 is formed such that the spiral slide surface 71 makes one round around the piston rod central axis O, and both end portions of the spiral slide surface 71. A step 72 is formed between them.

  In the first and second spiral slide rings 70 and 80, the respective spiral slide surfaces 71 and 81 are inclined at the same angle with respect to a plane orthogonal to the piston rod central axis O, and both are coaxially contacted with each other. The end faces 76 and 86 are configured to extend in parallel with each other by contact.

  The first and second spiral slide rings 70 and 80 are respectively formed with holes 74 and 84 into which a tool (not shown) is inserted. An operator rotates the first and second spiral slide rings 70 and 80 relative to each other through tools inserted into the holes 74 and 84 when the piston 50 described later is assembled.

  FIG. 2B is an enlarged view of a portion A in FIG. As shown in FIG. 2B, the relative rotation locking means 63 that locks the relative rotation of the first and second spiral slide rings 70, 80 is wedge-shaped that engages with the spiral slide surfaces 71, 81. Step surfaces 73 and 83 are formed at a constant pitch. The wedge-shaped step surfaces 73 and 83 are inclined in one direction with respect to a plane orthogonal to the piston rod central axis O, and when an axial force is applied to the first and second spiral slide rings 70 and 80, the first, The second spiral slide rings 70 and 80 are configured to have a rotational force that relatively rotates in the direction in which the ring width L of both is increased. As a result, when the first and second spiral slide rings 70 and 80 are to be relatively rotated in the direction in which the ring width L of both is reduced, the ring width L of both is increased. In the fastened state in which axial forces approaching the rings 70 and 80 are acting, the relative rotation of the first and second spiral slide rings 70 and 80 is locked.

  An annular groove 36 is formed on the outer peripheral surface of the piston mounting shaft portion 32 as the second spiral slide ring locking means 64 for locking the displacement of the second spiral slide ring 80 in the piston rod central axis O direction. A C-shaped ring 62 is fitted in the groove 34.

  An annular recess 85 is formed at the inner peripheral end of the second spiral slide ring 80, and the annular recess 85 is fitted into the ring 62. As a result, the second spiral slide ring 80 is locked by the ring 62 in the leftward direction in FIG. 1 and FIG. Further, when the annular recess 85 is fitted to the outer periphery of the ring 62, it is locked that the ring 62 is expanded in diameter and detached from the annular groove 36.

  The C-shaped ring 6 is fitted to the bush mounting shaft portion 33, and the bush 5 is prevented from coming off. The bush 5 is interposed between the end surface 37 of the piston mounting shaft portion 32 and the ring 6.

  A seal ring 8 is interposed between the bush 5 and the bush mounting shaft portion 33, and the oil-tightness of this portion is removed.

  Main parts constituting the hydraulic cylinder 1 such as the cylinder tube 10, the piston rod 30, the piston 50, the cylinder head 40, the first and second spiral slide rings 70 and 80 are made of metal such as steel.

  Next, the procedure for assembling the hydraulic cylinder 1 will be described.

  First, the cylinder head 40, the seal ring 7, the bush 4, the ring 61, the piston 50, the first spiral slide ring 70, and the second spiral slide ring 80 are sequentially fitted to the piston mounting shaft portion 32.

  Subsequently, an unillustrated assembling jig is used, and this assembling jig pulls the piston mounting shaft portion 32 and extends it in the direction of the central axis O by elastic deformation. This assembling jig has a part that abuts on the end face 54 of the piston 50 and a part that grips the bush mounting shaft portion 33, and both parts are separated by a predetermined tensile load. At this time, the tensile load applied to the piston mounting shaft portion 32 by the assembly jig is set to be larger than the thrust of the hydraulic cylinder 1.

  Subsequently, the ring 62 is fitted into the annular groove 36.

  Subsequently, the first and second spiral slide rings 70, 80 are rotated relative to each other through a tool inserted into each hole 74, 84, and no gap is created between the end face 54 of the piston 50 and the ring 62. As described above, the ring width L of the first and second spiral slide rings 70 and 80 is adjusted.

  Subsequently, the operator operates the assembly jig to release the pull of the piston mounting shaft portion 32, and the piston 50 is fastened to the piston rod 30. That is, when the displacement of the second spiral slide ring 80 in the direction of the central axis O is locked by the ring 62, a predetermined pressing load is applied to the piston 50 by the first and second spiral slide rings 70, 80. The pressing load applied to the piston 50 by the first and second spiral slide rings 70 and 80 is set larger than the thrust of the hydraulic cylinder 1.

  Subsequently, the seal ring 8, the bush 5, and the ring 6 are sequentially fitted to the bush mounting shaft portion 33. As a result, a piston rod assembly in which the components are assembled to the piston rod 30 is completed.

  Subsequently, the piston rod 30 is assembled to the cylinder tube 10, and the cylinder head 40 is fastened to the cylinder tube 10. Thereby, the assembly of the hydraulic cylinder 1 is completed.

  Next, the operation will be described.

  When the hydraulic cylinder 1 is operated, the piston 50 is moved in the direction of the central axis O by the hydraulic pressure guided to the oil chambers 2 and 3, and the piston rod 30 is extended and retracted from the cylinder tube 10 to drive the load. appear. For example, in the case of a crane, the boom of the crane rotates as the hydraulic cylinder 1 expands and contracts.

  The hydraulic cylinder 1 is provided with a predetermined pressing load larger than the thrust of the hydraulic cylinder 1 on the piston 50 by the first and second spiral slide rings 70, 80, so that the oil chambers 2, 3 are operated when the hydraulic cylinder 1 is operated. Since there is no backlash that causes displacement of the piston 50 with respect to the piston rod 30 due to the oil pressure guided to the cylinder, the impact generated between the piston 50 and the piston rod 30 is kept small, and the durability of the piston 50 and the piston rod 30 is ensured. The

  In the hydraulic cylinder 1, since the piston 50 and the first and second spiral slide rings 70 and 80 are fitted side by side on the piston mounting shaft portion 32 having an outer diameter D2, the piston 50 and the first spiral slide ring 70 and 80 are fitted together. Further, the diameter of the piston rod 30 is not reduced between the second spiral slide rings 70 and 80, and the strength of the piston rod 30 can be prevented from decreasing at this portion.

  In addition, since the piston rod 30 is formed with the same diameter at the portion where the piston 50 is fitted and the portion where the first and second spiral slide rings 70 and 80 are fitted, the cutting process applied to the piston rod 30 is reduced. It is.

  As described above, in the present embodiment, the piston rod 30 that drives the load, the cylindrical piston 50 to which the hydraulic pressure is guided, and the piston that locks the displacement of the piston 50 in the direction of the piston rod central axis O relative to the piston rod 30. A piston coupling structure comprising a locking means 65 and a piston fastening means 60 for fastening the piston 50 to the piston rod 30, wherein the piston fastening means 60 has a ring width in the direction of the piston rod central axis O depending on the relative rotational position. First and second spiral slide rings 70 and 80 in which L changes, and second spiral slide ring locking means 64 for locking the displacement of the second spiral slide ring 80 in the piston rod central axis O direction with respect to the piston rod 30 The relative rotational position of the first and second spiral slide rings 70 and 80 when the piston 50 is assembled And configured to apply a predetermined axial force on the piston 50 by adjusting the.

  Based on the above-described configuration, the piston rod 30 can be formed with the same outer diameter D2 at the part where the piston 50 is fitted and the part where the first and second spiral slide rings 70 and 80 are fitted. The diameter of the shaft portion 32 can be minimized, and the strength of the piston rod 30 can be improved. That is, the piston rod 30 does not reduce the diameter of the piston rod 30 between the piston 50 and the first and second spiral slide rings 70 and 80 unlike the conventional threaded portion. The strength is prevented from decreasing, and the durability of the piston rod 30 is ensured. And since the site | part in which the piston 50 fits and the site | part in which the 1st, 2nd spiral slide rings 70 and 80 fit are formed in the same diameter, the cutting process given to the piston rod 30 reduces. The cost of the product can be reduced.

  In the present embodiment, the first and second spiral slide rings 70 and 80 have spiral slide surfaces 71 and 81 that are inclined at the same angle with respect to a plane orthogonal to the piston rod central axis O, respectively. .

  Based on the above configuration, the first and second spiral slide rings 70, 80 are fitted to the piston rod 30, and the respective spiral slide surfaces 71, 81 come into contact with each other, so that the entire circumference of the piston 50 is reached. Uniform axial force is applied across the piston rod 30, and bending stress is not generated in the piston rod 30, and the durability of the piston rod 30 is ensured.

  In the present embodiment, a tensile load is applied to the piston rod 30 using an assembly jig, and the first and second spiral slide rings 70 are in a state where the piston rod 30 is stretched by elastic deformation in the direction of the piston rod central axis O. , 80 after adjusting the relative rotational position, the tensile load applied to the piston rod 30 is released using an assembling jig so that the first and second spiral slide rings 70, 80 have a predetermined axial force applied to the piston 50. It was set as the structure which provides.

  Based on the above configuration, the first and second spiral slide rings 70, 80 can accurately adjust a predetermined axial force to the piston 50, and quality can be improved.

  In the present embodiment, the tensile load applied to the piston rod 30 using an assembly jig is set to be larger than the thrust that the piston rod 30 drives the load, and the piston 50 and the second spiral slide ring locking means 64 are The ring width L of the first and second spiral slide rings 70 and 80 is adjusted so as not to create a gap therebetween.

  Based on the above configuration, the first and second spiral slide rings 70, 80 apply an axial force to the piston 50 that is greater than the thrust that the piston rod 30 drives the load, and the piston rod 30 drives the load during operation. As a result, the backlash that the piston 50 displaces with respect to the piston rod 30 is eliminated, the impact generated between the piston 50 and the piston rod 30 is suppressed to a small level, and the durability of the piston 50 and the piston rod 30 is ensured.

  In the present embodiment, as relative rotation locking means 63 that locks the relative rotation of the first and second spiral slide rings 70, 80, wedge-shaped step surfaces 73 that engage with the spiral slide surfaces 71, 81, 83 is formed.

  Based on the above configuration, the wedge-shaped staircase surfaces 73 and 83 are kept engaged with each other by the axial force pressing the spiral slide surfaces 71 and 81 together, and the relative rotation of the first and second spiral slide rings 70 and 80 is engaged. Stopped. In this case, since the step surfaces 73 and 83 are integrally formed with the first and second spiral slide rings 70 and 80, the structure can be simplified without increasing the number of components.

  Further, the relative rotation locking means 63 may be configured to lock the relative rotation of the first and second spiral slide rings 70 and 80 by a frictional force generated between the spiral slide surfaces 71 and 81.

  In the present embodiment, the piston locking means 65 includes an annular groove 34 formed on the outer periphery of the piston rod 30 and a ring 61 fitted in the annular groove 34.

  Based on the above configuration, the ring 61 fitted into the annular groove 34 abuts on the piston 50 and locks the displacement of the piston 50 in the direction of the piston rod central axis O with respect to the piston rod 30.

  In this structure, an annular step portion is integrally formed on the outer periphery of the piston rod 30, and the cutting process applied to the piston rod 30 is reduced compared to a structure in which the piston 50 is locked by the annular step portion. Down is taken.

  In the present embodiment, the second spiral slide ring locking means 64 includes an annular groove 36 formed on the outer periphery of the piston rod 30 and a ring 62 fitted in the annular groove 36.

  Based on the above configuration, the ring 62 fitted in the annular groove 36 abuts on the second spiral slide ring 80 and locks the displacement of the second spiral slide ring 80 in the direction of the piston rod central axis O with respect to the piston rod 30. .

  Compared with the structure in which the thread portion is formed on the outer periphery of the piston rod 30 and the second spiral slide ring 80 is locked by this thread portion, this structure reduces the cutting work applied to the piston rod 30 and reduces the product. Cost reduction is planned.

  Also, the piston locking means 65 and the second spiral slide ring locking means 64 are locked using the rings 61 and 62, respectively, and the annular grooves 34 and 36 in which the rings 61 and 62 are fitted to the piston mounting shaft portion 32, respectively. By adopting a structure in which the diameter of the piston rod 30 is formed, the diameter of the piston mounting shaft portion 32 can be minimized and the strength of the piston rod 30 can be improved.

  Next, another embodiment shown in FIG. 4 will be described. This basically has the same configuration as that of the embodiment shown in FIGS. 1 to 3, and only different portions will be described. In addition, the same code | symbol is attached | subjected to the same structure part as the said embodiment.

  The first spiral slide ring 70 is integrally formed with the piston 50. The first spiral slide ring 70 protrudes from the end surface 54 of the piston 50, and the spiral slide surface 71 is formed so as to make one round around the piston rod central axis O, and between the both ends of the spiral slide surface 71. A step 72 is formed.

  In this case, when the piston 50 is assembled, a predetermined axial force is applied to the piston 50 by adjusting the rotational position of the second spiral slide ring 80 with respect to the first spiral slide ring 70 integrated with the piston 50.

  Based on the above configuration, the first spiral slide ring 70 is provided integrally with the piston 50, thereby reducing the number of parts and simplifying the structure.

  Next, another embodiment shown in FIG. 5 will be described. This basically has the same configuration as that of the embodiment shown in FIGS. 1 to 3, and only different portions will be described. In addition, the same code | symbol is attached | subjected to the same structure part as the said embodiment.

  The relative rotation locking means 63 includes a screw 67 that is screwed into the first and second spiral slide rings 70 and 80, and a ball (lock member) 68 that is pressed against the piston rod 30 by the screw 67.

  A concave portion 38 with which the ball 68 is engaged is formed on the outer peripheral surface of the piston mounting shaft portion 32.

  When the piston 50 is assembled, after adjusting the rotational position of the second spiral slide ring 80 with respect to the first spiral slide ring 70, the respective screws 67 respectively screwed to the first and second spiral slide rings 70, 80 are tightened, As each ball 68 engages with each recess 38, the rotation of the first and second spiral slide rings 70, 80 relative to the piston rod 30 is locked.

  Based on the above configuration, when the ball (lock member) 68 is pressed against the piston rod 30, the rotation of the first and second spiral slide rings 70 and 80 with respect to the piston rod 30 is reliably locked.

  The ball (lock member) 68 may be eliminated, and the tip of the screw 67 may be directly engaged with the recess 38 formed on the outer peripheral surface of the piston mounting shaft 32.

  Further, the concave portion 38 formed on the outer peripheral surface of the piston mounting shaft portion 32 is abolished, and a recess whose curvature radius substantially coincides with the outer peripheral surface of the piston mounting shaft portion 32 is formed in the ball (lock member) 68. It is good also as a structure by which rotation of the 1st, 2nd spiral slide rings 70 and 80 with respect to the piston rod 30 is latched by pressing on the outer peripheral surface of the piston attachment shaft part 32.

  Next, another embodiment shown in FIG. 6 will be described. This basically has the same configuration as that of the embodiment shown in FIGS. 1 to 3, and only different portions will be described. In addition, the same code | symbol is attached | subjected to the same structure part as the said embodiment.

  The first and second spiral slide rings 70 and 80 are arranged on the side where the piston rod 30 extends to the load with respect to the piston 50.

  In other words, the piston 50 is disposed on the end portion side of the piston rod 30 with respect to the first and second spiral slide rings 70 and 80.

  In this case, the bush 4, the ring 62, the second spiral slide ring 80, the first spiral slide ring 70, the piston 50, and the ring 61 are fitted into the piston mounting shaft portion 32 in order.

  Based on the above configuration, the piston 50 moves away from the bush 4 and approaches the bush 5 as compared to the embodiment shown in FIGS.

  Thus, by providing the first and second spiral slide rings 70 and 80 as the piston fastening means 60, the piston fastening means 60 is arranged as shown in FIG. It becomes possible to arrange | position to the piston rod 30 side, and the arrangement | positioning freedom degree of piston 50 with respect to the piston rod 30 can be raised.

  The fluid pressure actuator to which the present invention is applied is not limited to hydraulic oil, and a hydraulic fluid such as a water-soluble alternative liquid or air may be used.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

1 is a cross-sectional view of a hydraulic cylinder showing an embodiment of the present invention. Sectional drawing which similarly shows the coupling structure of a piston. The perspective view of a 2nd spiral slide ring similarly. Sectional drawing which shows the coupling structure of the piston which shows other embodiment. Sectional drawing which shows the coupling structure of the piston which shows other embodiment. Sectional drawing which shows the coupling structure of the piston which shows other embodiment. Sectional drawing which shows the coupling structure of the piston which shows a prior art example.

Explanation of symbols

1 Hydraulic cylinder (fluid pressure actuator)
30 piston rod 32 piston mounting shaft 34 annular groove 36 annular groove 50 piston 60 piston fastening means 61 ring 62 ring 63 relative rotation locking means 64 second spiral slide ring locking means 65 piston locking means 67 screw 68 ball (lock Element)
70 first spiral slide ring 71 spiral slide surface 73 step surface 80 second spiral slide ring 81 spiral slide surface 83 step surface 85 annular recess

Claims (7)

A piston rod that drives the load;
A cylindrical piston through which fluid pressure is guided;
Piston locking means for locking the displacement of the piston in the axial direction of the piston rod with respect to the piston rod;
A piston coupling structure comprising piston fastening means for fastening the piston to the piston rod,
As the piston fastening means,
First and second spiral slide rings in which the ring width in the direction of the piston rod central axis changes depending on the relative rotational position;
A second spiral slide ring locking means for locking the displacement of the second spiral slide ring with respect to the piston rod in the axial direction of the piston rod;
A piston coupling structure characterized in that a predetermined axial force is applied to the piston by adjusting a relative rotational position of the first and second spiral slide rings when the piston is assembled.   The said 1st, 2nd spiral slide ring was set as the structure which has respectively the spiral slide surface which inclines at the mutually same angle with respect to the plane orthogonal to the said piston rod central axis. Piston coupling structure. A tensile load is applied to the piston rod using an assembly jig,
After adjusting the relative rotational position of the first and second spiral slide rings in a state where the piston rod is extended by elastic deformation in the piston rod central axis direction,
The first and second spiral slide rings are configured to apply a predetermined axial force to the piston by releasing a tensile load applied to the piston rod using the assembly jig. Item 3. The piston coupling structure according to Item 1 or 2. The tensile load applied to the piston rod using the assembly jig is set larger than the thrust that the piston rod drives the load,
4. The ring width of the first and second spiral slide rings is adjusted so as not to create a gap between the piston and the second spiral slide ring locking means. Piston coupling structure.   The piston coupling structure according to any one of claims 1 to 4, wherein the first spiral slide ring is integrally formed with the piston.   3. A wedge-shaped stepped surface that engages with each other on the spiral slide surface is formed as a relative rotation locking means for locking the relative rotation of the first and second spiral slide rings. The piston coupling structure according to any one of 5 to 5.   The piston coupling structure according to any one of claims 1 to 6, wherein the first and second spiral slide rings are arranged on a side where the piston rod extends to the load with respect to the piston.

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