JP4908987B2 - Piston ring manufacturing method and fluid pressure cylinder - Google Patents

Description

  The present invention is used as a bearing between a piston of a fluid pressure cylinder and a manufacturing method of a synthetic resin piston ring having a cut surface for mounting to the piston, and a piston manufactured by this manufacturing method The present invention relates to a fluid pressure cylinder provided with a ring.

A piston ring used as a bearing between the piston and the cylinder of the hydraulic cylinder, polyimide (TPI: Polyimide) is manufactured of a synthetic resin such as, also mounted than the outer diameter of the piston ring in the small-diameter piston ring groove For this reason, there is one provided with a cut surface by cutting one place on the circumference of the piston ring.

  FIG. 5 shows the background art of the manufacturing method of such a piston ring, (a) is a diagram showing a state in which a pistol is resin-molded with a mold, and (b) is a state where the piston ring is taken out from the mold. A front view showing a piston rig, (c) is a front view showing a state in which a piston ring after molding is cut, (d) is a perspective view of (c), and (e) is a heat correction process for removing stress on the piston ring thereafter. The figure which shows the state which is carrying out, (f) is a perspective view which shows the place which attaches the piston ring which completed the heat correction process of stress removal between a piston and a cylinder.

  First, as shown in FIG. 5A, a synthetic resin is injected into the mold K, and the piston ring 21A is resin-molded. Here, the symbol “A” means a piston ring in a mold state in the mold K. Hereinafter, the same symbols are used for piston rings.

  When this piston ring 21A is removed from the mold, as shown in FIG. 5B, the piston ring contracts as a whole due to molding residual stress, resulting in a piston ring 21B having a further reduced diameter.

  When this piston ring 21B is cut at one place in the radial direction, as shown in FIGS. 5C and 5D, the residual tensile molding inside the piston ring 21B, particularly the outer peripheral surface (including the inner portion in the vicinity of the peripheral surface). It is known that the piston ring 21 </ b> C is in a state in which the stress is released and the cut surface 21 a is widened to increase the diameter as a whole.

  The reason for cutting in this way is to enable the piston ring to be fitted into the piston ring groove beyond the outer periphery of the piston as described above.

  In addition, the cutting method that forms the oblique cutting surface 21a as shown in FIGS. 5C and 5D is called bias cutting, and the sealing performance due to permanent deformation changes due to the cutting of the piston ring. In order to compensate for this, the sealing performance is better maintained in the operating temperature range of the cylinder.

  However, in the piston ring 21 </ b> C whose diameter has been expanded by cutting, there is a lot of resistance when the piston 22 is inserted into the cylinder 25, and the piston ring 21 </ b> C protrudes from the end face of the cylinder 25, making insertion difficult. It was.

  Therefore, as shown in FIG. 5 (e), the inner and outer diameters of the piston ring 21C are constrained by the correction jigs 31 and 32 so that the inner and outer diameters of the piston ring become favorable in a natural state, and constant at high temperatures. Heat correction treatment was performed to remove molding residual stress for a period of time (usually about half a day to about a day).

  The piston ring 21 subjected to the heat correction process is reduced in diameter as a whole, and the interval between the cut surfaces 21a is narrower as shown in FIG. Therefore, as shown in the drawing, the piston 22 can be more easily inserted into the cylinder 25 with the piston ring 21 fitted in the piston ring groove 22a on the outer periphery of the piston 22.

  However, the heat correction process for this requires a certain time, and a solution has been desired. Moreover, although the piston ring of the same use is described in patent document 1, there was no description about the problem which arises by a cutting | disconnection, and the solution means.

Further, if a piston ring by a manufacturing method that solves this problem is used, productivity can be improved even in a fluid pressure cylinder.
JP 2001-304413 A (FIGS. 1 and 2)

  The present invention is intended to improve the above-described problem, and a piston ring manufacturing method capable of avoiding the influence of molding residual stress by a short processing time, and a fluid pressure cylinder using the piston ring manufactured by this manufacturing method. The purpose is to provide.

The piston ring manufacturing method of the present invention is a method for manufacturing a synthetic resin piston ring which is used as a bearing between a piston of a fluid pressure cylinder and has a cutting surface for mounting to the piston. after molding as before cutting, or after cutting, on the outer periphery of the piston ring, it has rows antistress working against the molding residual stress remaining in the outer peripheral surface after molding, wherein the anti-stress processing, molding residual stress It is characterized by plastic working that generates residual processing stress that resists the above.

  In the present invention, it is a problem to remove the influence of the molding residual stress of the piston ring, and this molding residual stress is generated inside the piston ring after molding, but it increases the diameter after cutting. It is mainly the molding residual stress that exists inside the outer peripheral surface of the piston ring and in the vicinity thereof that is concerned.

  Therefore, in the present invention, when “outer peripheral surface” is described, it means “the outer peripheral surface and the inside in the vicinity thereof”.

  The fluid pressure cylinder of the present invention is characterized in that the piston ring manufactured by the above manufacturing method is used as a bearing between the piston and the cylinder.

According to the piston ring manufacturing method of the present invention, a piston ring made of a synthetic resin is used as a bearing between a piston of a fluid pressure cylinder and has a cut surface for mounting to the piston. after the molding of a ring, prior to cutting, or after cutting, on the outer periphery of the piston ring, as an anti-stress working against the molding residual stress remaining in the outer peripheral surface after molding, machining residual stress against the molding residual stress since the plastic working causing, it is possible to avoid the influence of molding the residual stress in a short time of processing.

  According to the fluid pressure cylinder of the present invention, since the piston ring manufactured by the above manufacturing method is used as a bearing between the piston and the cylinder, the effect of the above manufacturing method, that is, the cost reduction effect by improving the productivity is Demonstrates as a cylinder.

  Hereinafter, embodiments (examples) of the present invention will be described with reference to the drawings.

  1A and 1B show an example of a method for producing a piston ring according to the present invention. FIG. 1A is a view showing a state where a pistol is molded with a mold, and FIG. 1B is a piston rig taken out from the mold. (C) is a perspective view showing a state where plastic processing is performed on the outer periphery of the piston ring after molding, (d) is a front view showing a state in which the piston ring is cut, and (e) is ( It is a perspective view of d).

  The manufacturing method of the piston ring of the present invention is a manufacturing method of a synthetic resin piston ring which is used as a bearing between the pistons of a fluid pressure cylinder and has a cut surface for mounting to the piston. However, the present invention is characterized in that, in order to remove the molding residual stress, the anti-stress machining that is machining is used without using the heat correction treatment as in the background art.

  In this manufacturing method, as shown in FIG. 1 (a), a piston ring is resin-molded with a mold K to obtain a molded piston ring 1A in the mold, and this is taken out, and FIG. As shown in FIG. 5, the process up to obtaining the contracted piston ring 1B is the same as the manufacturing method of the piston rings 21A and 21B of the background art shown in FIGS.

  In addition, as a material of the piston ring which is an object of the manufacturing method of the present invention, a synthetic resin, particularly, polyimide (TPI: Polyimide) is preferable.

  In this manufacturing method, after that, before cutting the circumference of the piston ring, as shown in FIG. 1 (c), the piston ring 1B is not slid on the outer periphery of the shaft type processing jig 11 (with the jig 11 and It is characterized in that knurling is performed by the knurling piece 15 on the outer periphery of the piston ring 1B while fitting and rotating the shaft type processing jig 11 so as to rotate together.

  When such plastic working is performed on the outer periphery of the piston ring 1B, a processing residual stress against the molding residual stress on the outer periphery is generated. As a result, even if the circumference of the piston ring is cut thereafter, As shown in FIGS. 1D and 1E, the cut surfaces 1a contact each other without being separated from each other, or the interval is reduced to such an extent that the piston ring 1 can be easily mounted.

Such an effect of plastic working has been confirmed by the inventors ' experiments.

  The piston ring 1 manufactured in this way is equivalent to the piston ring 21 subjected to the heat correction process in the background art or is in a state of being further reduced in diameter, so that the mounting between the cylinder and the piston is equivalent to the background art. Or easier than the background art.

  In addition, according to this manufacturing method, compared with the heat correction processing that requires about a day, since it is a simple machining, it can be completed in a time of several seconds to several minutes, and the molding residual stress can be reduced in a short time. The influence can be avoided.

  In addition to the knurling process exemplified here, the plastic processing that causes the processing residual stress to resist such forming residual stress is not only for the outer periphery being pressed with a roller, but also for the outer peripheral key points. Includes those that cause punching (point compression) and punching with a large number of needles that do not have sharp points, such as those that cause processing residual stress in the direction opposite to the molding residual stress on the surface of the piston ring. .

  Further, in the above, an example in which the plastic working that generates the machining residual stress against the molding residual stress is performed before the piston ring is cut, but according to the experiment of the present inventor, the plastic working is performed after the piston ring is cut. However, it is understood that the same effect is exhibited.

However, when cutting first, the piston ring expands in diameter as shown in FIGS. 5 (c) and 5 (d). It needs to be big.
<Reference Example 1>

FIG. 2 shows a reference example of a method for manufacturing a piston ring according to the present invention. (A) is a diagram showing a state where a piston ring is resin-molded with a mold, and (b) is a state where the piston ring is taken out from the mold. The front view which shows a piston rig, (c) is a perspective view which shows the state which is cutting the outer periphery of the piston ring after shaping | molding, (d) is a front view which shows the state which cut | disconnected the piston ring after that, (e) is It is a perspective view of (d). Thus, the parts already described are assigned the same reference numerals and redundant description is omitted.

  2A and 2B are the same as those in FIG. 1, but as shown in FIG. 2C, this method is performed before cutting the circumference of the piston ring. The processing is different in that the shaft processing jig 11 is rotated while the outer periphery of the piston ring 1B is cut by a cutter 16 to cut the molding residual stress.

  The cutter 16 is formed by stacking a plurality of rotary blades sharpened at an acute angle. While rotating the cutter 16, the cutter 16 is cut in the axial direction with respect to the outer periphery of the piston ring 1B in series. A cutting process is performed in which only a cut is made on the outer periphery of 1B without applying pressure.

  When such a cutting process is performed, it is considered that the molding residual stress existing on the outer peripheral surface of the piston ring 1B is divided as described above. According to the experiments of the present inventors, FIG. As shown in e), the processed piston ring 1 ′ is in a state where the cut surfaces 1 a are in contact with each other, or the interval is easily attached to the piston ring 1 B, as in the manufacturing method of FIG. It will be as small as possible.

  Therefore, the manufacturing method using cutting that divides the molding residual stress exhibits the same effect as the manufacturing method using plastic processing in FIG. 1, and the piston ring 1 ′ manufactured in this way is also used in the piston ring in FIG. 1 exhibits the same effect.

  In addition, the cutting process for dividing the molding residual stress is not only a cut process by the cutter exemplified here, but also a needle thread, and a large number of holes are formed on the outer periphery. This includes a cutting edge of a piston ring that cuts off the molding residual stress generated on the outer peripheral surface of the piston ring, such as a large flat blade edge, such as a large number of holes.

  Further, in the above, an example in which the cutting process for dividing the molding residual stress is performed before the piston ring is cut, but according to the experiment of the present inventor, the same effect can be obtained even after the piston ring is cut. It is understood that it will be demonstrated.

Note that both the plastic working that causes the processing residual stress that resists the molding residual stress that is characteristic of the manufacturing method of FIG. 1 and the cutting that divides the molding residual stress that is characteristic of the manufacturing method of FIG. In the present invention, both are collectively referred to as anti-stress processing that resists the molding residual stress remaining on the outer peripheral surface of the piston ring after molding.
<Reference Example 3>

FIG. 3 shows another reference example of the manufacturing method of the piston ring according to the present invention, in which (a) is a perspective view showing a state in which the outer periphery of the piston ring after molding is obliquely cut, and (b) is Then, the front view which shows the state which cut | disconnected the piston ring, (c) is a perspective view of (b).

  This manufacturing method is different from the manufacturing method shown in FIGS. 1 and 2 in that an oblique cut is made in the outer periphery of the piston ring 1B by an oblique blade cutter 17, as shown in FIG. 3A.

  According to the present inventor, it is known that the molding residual stress is also divided by the outer peripheral machining by the oblique blade cutter 17, and such machining also divides the molding residual stress included in the manufacturing method of FIG. Corresponds to cutting.

  In other words, the anti-stress machining effect is exhibited even by such a cutting process in which oblique cuts are made, and as shown in FIGS. 3B and 3C, the piston ring 1 ″ after processing is manufactured by the method shown in FIG. As in the case of, the cut surfaces 1a are in contact with each other, or the distance between them is so small that the piston ring can be easily mounted.

  Therefore, the manufacturing method of the oblique cut also exhibits the same effect as the manufacturing method of FIGS. 1 and 2, and the manufactured piston ring 1 ″ has the same effect as the piston rings 1 and 1 ′ of FIGS. Demonstrate.

  Also in this case, the effect of cutting the oblique cut is not changed even before the piston ring is cut or after the piston ring is cut.

  The piston ring of Patent Document 1 also has an oblique cut similar to the outer periphery of the piston ring 1 ″. Compared only in this respect, the configuration is the same as the piston ring 1 ″.

  However, the oblique cut provided on the outer periphery of the piston ring of Patent Document 1 is for promoting lubrication in the axial direction of the ring, and the oblique cut provided on the outer periphery of the piston ring of the present invention is This is for dividing the molding residual stress remaining on the outer periphery, and the problem to be solved is different.

  In the present invention, as a result of the inventor of Patent Document 1 diligently studying the oblique cut provided on the outer periphery of the piston ring of Patent Document 1, this cut also causes a diameter expansion phenomenon that occurs when the piston ring is cut. It was found that it was made smaller, and this was developed, and was born as a larger and special invention idea called anti-stress machining.

  On the other hand, if the cutting process that divides the molding residual stress, which is one of the anti-stress processes, is to generate oblique cuts on the outer periphery of the piston ring 1 ″, the effect of dividing the molding residual stress and Patent Document 1 are disclosed. Two effects can be achieved simultaneously with the lubrication effect of the piston ring.

  In recent years, in knurling, there has been provided what performs knurling by cutting instead of so-called rolling.

According to this cutting knurl, it seems that a constant plastic processing can be applied to the outer periphery of the piston ring simultaneously with the cutting processing. In that case, the cutting processing and the molding residual stress are divided. It seems that the effect of plastic working against the above is exhibited.
<Example 2>

  FIG. 4 is a longitudinal sectional view showing an example of a fluid pressure cylinder including a piston ring manufactured by the manufacturing method of the present invention.

  The fluid pressure cylinder 10 includes a cylinder 5, a piston 2 that slides fluid-tightly within the cylinder 5, a piston rod 3 that includes the piston 2 at a tip and outputs a linear driving force generated by a working fluid to the outside. It has.

  A piston ring groove 2 a is provided on the outer periphery of the piston 2, and the piston ring 1 manufactured by the manufacturing method of the present invention is attached to the piston ring groove 2 a as a bearing between the cylinder 5 and the piston 2. .

  Therefore, this fluid pressure cylinder 10 enjoys and exhibits the effect of the above-described piston ring 1 and the effect of the above-described manufacturing method of the piston ring as a fluid pressure cylinder while exhibiting the basic function as the fluid pressure cylinder. be able to.

  Further, instead of the piston ring 1, a piston ring 1 ′ and a piston ring 1 ″ can be used. In that case, the effect of each piston ring and the effect of the manufacturing method of the piston ring can be used as a fluid pressure cylinder. You can enjoy and demonstrate it.

  In particular, when the piston ring 1 ″ is used, the lubricating effect of the piston ring described in Patent Document 1, that is, a lateral load is applied to the fluid pressure cylinder, and the contact portion between the cylinder inner surface and the piston ring surface is pressed against each other. Moreover, the effect that the oil film interposed between them cannot be broken can also be exhibited.

  In addition, the manufacturing method of the piston ring and the fluid pressure cylinder of the present invention are not limited to the above-described embodiments, and various modifications and combinations are possible within the scope described in the claims and the scope of the embodiments. .

  In addition, the fluid pressure cylinder of the present invention may be used as an actuator or a shock absorber.

  The manufacturing method of a piston ring and the fluid pressure cylinder of the present invention can be used in an industrial field in which it is required to avoid the influence of the molding residual stress generated on the surface of the piston ring in a short time.

BRIEF DESCRIPTION OF THE DRAWINGS It shows an example of the manufacturing method of the piston ring of this invention, (a) is a figure which shows the state which is carrying out resin molding of the pistol with a metal mold | die, (b) is a front view which shows the piston rig of the state taken out from the metal mold | die. (C) is a perspective view which shows the state which is plastic-working on the outer periphery of the piston ring after shaping | molding, (d) is a front view which shows the state which cut | disconnected the piston ring after that, (e) is a perspective view of (d). Figure The reference example of the manufacturing method of the piston ring of this invention is shown, (a) is a figure which shows the state which is carrying out resin molding of the pistol with a metal mold | die, (b) is the front which shows the piston rig of the state taken out from the metal mold | die. (C) is a perspective view showing a state where the outer periphery of the piston ring after molding is cut, (d) is a front view showing a state in which the piston ring is cut, and (e) is a view of (d). Perspective view The other reference example of the manufacturing method of the piston ring of this invention is shown, (a) is a perspective view which shows the state which is carrying out the diagonal notch processing on the outer periphery of the piston ring after shaping | molding, (b) is piston ring after that The front view which shows the state which cut | disconnected, (c) is a perspective view of (b) The longitudinal cross-sectional view which shows an example of the fluid pressure cylinder provided with the piston ring manufactured with the manufacturing method of this invention BRIEF DESCRIPTION OF THE DRAWINGS The background art of the manufacturing method of the piston ring of this invention is shown, (a) is a figure which shows the state which is resin-molding the piston ring with a metal mold | die, (b) is the front which shows the piston rig of the state taken out from the metal mold | die. (C) is a front view showing a state in which the molded piston ring is cut, (d) is a perspective view of (c), and (e) is then subjected to heat correction processing for stress removal on the piston ring. The figure which shows a state, (f) is a perspective view which shows the place which installs the piston ring which completed the heat correction process of stress removal between a piston and a cylinder.

Explanation of symbols

1, 1 ', 1 "piston ring
1a Cut surface
2 piston
3 Piston rod
5 Cylinder 10 Fluid Pressure Cylinder 11 Shaft Type Jig 15 Knurling Piece (Plastic Processing Tool)
16 Cutter (Cutting tool)

Claims (3)

A method for producing a piston ring made of a synthetic resin, which is used as a bearing between a piston of a fluid pressure cylinder and a cylinder, and has a cutting surface for mounting to the piston,
After the resin molding of the piston ring , before or after cutting, the outer periphery of the piston ring is subjected to anti-stress processing that resists the molding residual stress remaining on the outer peripheral surface after molding,
The method of manufacturing a piston ring, wherein the anti-stress processing is plastic processing that generates a processing residual stress against a molding residual stress . The method for producing a piston ring according to claim 1, wherein the plastic working is knurling. A fluid pressure cylinder, wherein the piston ring manufactured by the manufacturing method according to claim 1 or 2 is used as a bearing between the piston and the cylinder.

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