JP3680882B2 - Manufacturing method of piston bearing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a piston bearing suitable for use in a pressure device such as a compressor or a shock absorber.
[0002]
[Prior art]
As disclosed in Japanese Patent Publication No. 4-81074, the applicant of the present application previously provided a plurality of annular engagement grooves 22 having a substantially trapezoidal cross section as shown in FIG. A resin-bearing pressure-bonded piston is proposed in which a resin-made piston bearing 23 is attached to the outer peripheral surface of the piston body 21 by pressure bonding, and a method for manufacturing the piston called “glidelight manufacturing method” is also proposed. Yes. The piston shown in FIG. 5 is formed by integrally molding a skirt-like seal lip 24 at one end of the piston bearing 23 in the axial direction, thereby providing a unidirectional sealing action.
[0003]
Therefore, when this piston is incorporated and operated, for example, in the compressor, when the piston moves leftward toward the compression chamber disposed on the left side of the piston in the figure, the seal lip 24 is moved to the inner wall of the cylinder tube by the high pressure of the air in the compression chamber. It is possible to prevent air from leaking to the right side of the piston through the seal lip 24, but when the piston moves to the right, the air from the anti-compression chamber side can be prevented. Since the seal lip 24 falls inward by the air pressure, it is impossible to prevent the lubricating oil that lubricates the sliding portion from passing through the seal lip 24 and flowing into the compression chamber. The lubricating oil flowing into the compression chamber cannot be recovered unless the compressor is disassembled, and if the lubricating oil is left flowing into the compression chamber, the volume of the compression chamber is substantially reduced, and If the pressure in the compression chamber is excessively increased, the operation of the compressor may be hindered.
[0004]
[Problems to be solved by the invention]
Accordingly, there is a demand for this type of resin bearing pressure-bonding piston to have a sealing property in the opposite direction to the extent that lubricating oil does not flow into the compression chamber, and the present invention aims to meet this demand. It is.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a piston bearing manufacturing method according to claim 1 of the present invention is attached to the outer peripheral surface of a piston body provided with a plurality of annular engaging grooves arranged in the axial direction by pressure bonding, and has a cylindrical end. A resin-made piston bearing provided with a seal lip on the outer peripheral surface of the piston bearing, and a plurality of annular ridges having a wedge shape in cross section are provided side by side in the axial direction, and the ridges have a pair of axially inclined surfaces. Provided, an inclination angle of the slope on the seal lip side is set smaller than an inclination angle of the slope on the opposite side, and an annular engagement portion that engages with the engagement groove is integrally formed on the inner peripheral surface of the piston bearing In the method of manufacturing a piston bearing in which the inner peripheral surface of the engagement portion is lifted from the groove bottom portion of the engagement groove, a plurality of annular engagement grooves are arranged in the axial direction on the outer peripheral surface of the piston body. Above The bottom of the groove is relatively shallow on the seal lip side and relatively deeply tapered on the opposite side, and a resin piston bearing is attached to the outer peripheral surface of the piston body by crimping. The elasticity of the piston bearing after installation A plurality of annular ridges are generated on the outer peripheral surface of the piston bearing corresponding to the engagement groove by the return, and the cross-sectional shape of the ridge has a wedge shape corresponding to the taper shape of the groove bottom. To do.
[0006]
[0007]
In the piston bearing manufactured by the above manufacturing method, as shown in a model diagram of FIG. 3 to be described later, the inclination angle is set to be relatively larger than the inclined surface 8a on the seal lip side where the inclination angle is set to be relatively small. Since the oil film entering from the side inclined surface 8b becomes thinner, it is possible to prevent the oil from rising from the latter inclined surface 8b side, and the annular raised portion 8 having a wedge shape in cross section slides on the inner wall of the cylinder tube 9. In order to exhibit a scraper function, it is possible to exhibit a seal function in the direction opposite to the seal lip.
[0008]
Further, according to the new knowledge of the present inventors regarding the manufacturing method of this kind of piston or piston bearing, when the piston shown in FIG. 5 is manufactured by the above-described glide light manufacturing method, as shown in FIG. The resin-made piston bearing 23 attached to the outer peripheral surface of the piston body 21 by pressure bonding is elastically restored (elastic recovery) to some extent in the radial direction, that is, in the thickness direction, and is engaged with the portion engaged with the engaging groove 22 at this time. Since there is a difference in the amount of elastic return between the mating grooves 22 and the portions that are not engaged with the engaging grooves 22, irregularities occur on the outer peripheral surface of the piston bearing 23, A raised portion 25 is generated at the outer periphery. The raised portion 25 has an annular shape corresponding to the annular shape of the engaging groove 22, and the engaging groove 22 has a trapezoidal cross section and is symmetrical with respect to the center line 0 in the left-right direction. It is also formed symmetrically. The present invention is an application of this.
[0009]
The previously proposed glide light manufacturing method includes a step of attaching a sheet by pressure-bonding it to an engagement groove provided on the outer periphery of the piston body via a sheet pressure-bonding means, as described in the above publication, A step of pressing and bending one end of the piston body to engage with a taper groove provided on the outer periphery of the piston body, a step of press-fitting a piston body with a sheet attached to the outer periphery into a heating cylinder, and heating the sheet; And a step of cooling the attached sheet. The seat is made of tetrafluoroethylene resin (PTFE), which becomes a piston bearing.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIGS. 1 and 2, a plurality of annular engagement grooves 2 (four in FIG. 1) are arranged in the axial direction on the outer peripheral surface of a piston body 1 made of a rigid material such as a metal having a columnar shape or a cylindrical shape. Further, one annular taper groove 3 is provided at one end of the piston body 1 along with the engagement groove 2. Each of the engaging grooves 2 has a groove bottom portion 2 a formed in a tapered shape, and a side wall portion 2 b formed in a vertical surface in a direction orthogonal to the central axis of the piston body 1. The tapered groove 3 has a groove bottom portion 3a formed in a cylindrical shape and a side wall portion 3b formed in a tapered shape.
[0011]
A piston bearing 4 made of ethylene tetrafluoride resin is attached to the outer peripheral surface of the piston body 1 by pressure bonding by the above-mentioned glide light manufacturing method, and an annular seal lip 5 having a skirt shape at one end of the piston bearing 4 is formed. Is integrally formed, and an annular tapered engaging portion 6 engaged with the tapered groove 3 is integrally formed at the other cylindrical end.
[0012]
An annular engaging portion 7 engaged with the engaging groove 2 by deformation of the piston bearing 4 due to the above-described pressure bonding is integrally formed on the inner peripheral surface of the piston bearing 4 corresponding to each engaging groove 2. The inner peripheral surface 7a of the engaging portion 7 has a tapered shape corresponding to the tapered shape of the groove bottom portion 2a.
[0013]
An annular raised portion 8 is integrally formed on the outer peripheral surface of the piston bearing 4 corresponding to each engaging groove 2 and engaging portion 7, and the sectional shape of the raised portion 8 is a taper of the groove bottom portion 2 a. Corresponding to the shape, it has a substantially wedge shape (substantially triangular). That the axial direction a pair of inclined surfaces 8a this ridge 8 is provided with a 8b, the inclination angle theta ₁ of the seal lip 5 side slopes 8a is set to be smaller than the inclination angle theta ₂ opposite the slope 8b.
[0014]
The piston bearing 4 having the above-described configuration is combined with the piston main body 1 to form a resin-bearing pressure-bonding piston, and is incorporated in a compressor as described above, for example, to provide a bearing action and a sealing action. The sealing action is a two-way seal with a sealing action by the seal lip 5 and a sealing action by the raised portion 8.
[0015]
That is, in FIG. 1, first, when the piston moves leftward toward the compression chamber disposed on the left side of the piston in the drawing, the seal lip 5 is strongly brought into close contact with the inner wall of the cylinder tube by the high pressure of the air in the compression chamber. The sealing action by the seal lip 5 can prevent air from passing through the seal lip 5 and leaking to the right side of the piston. On the contrary, when the piston moves to the right, the lubricating oil is removed by the sealing action by the raised portion 8. It is possible to prevent the gas from flowing into the compression chamber through the seal lip 5. The reason why the raised portion 8 having a substantially wedge-shaped cross section is effective in preventing the lubricating oil from flowing into the compression chamber is that, as shown in the model diagram of FIG. 3, the slope 8a on the seal lip side having a relatively small inclination angle. Since the oil film entering from the inclined surface 8b on the opposite side whose inclination angle is set to be relatively thin can be prevented from rising from the latter inclined surface 8b side, the annular raised portion 8 having a substantially wedge shape in cross section is also possible. This is because it slides on the inner wall of the cylinder tube 9 and exhibits a scraper action. Moreover, since the inner peripheral surface 7a of each engaging part 7 of the piston bearing 4 is lifted from the groove bottom part 2a of the engaging groove 2 with the elastic return, excellent cushioning properties are exhibited.
[0016]
The piston bearing manufacturing method according to claim 1 of the present invention is different from the above-described glide light manufacturing method in that a plurality of annular engaging grooves 2 are arranged on the outer peripheral surface of the piston body 1 in the axial direction. The groove bottom 2a of the joint groove 2 is formed in a tapered shape instead of a cylindrical shape. The taper has the same inclination direction and the same inclination angle. The direction of inclination of the taper is set to be relatively shallow on the side of the skirt-like seal lip 5 provided at one end of the piston bearing 4 and relatively deep on the opposite side, that is, the side of the seal lip 5 is the compression chamber side in the compressor ( High pressure side). Further, as described above, the side wall 2b of each engagement groove 2 is formed on a vertical plane orthogonal to the central axis of the piston body 1, but this may be tapered as in the piston of FIG. .
[0017]
Next, in the same manner as in the above glide light manufacturing method, a sheet made of ethylene tetrafluoride resin to be the piston bearing 4 is attached to the outer peripheral surface of the piston main body 1 via the sheet pressing means, and one end of the sheet is pressed and bent. The piston body 1 fitted with a sheet is press-fitted into a heating cylinder by being engaged with a taper groove 3 provided on the outer peripheral surface of the piston body 1 to heat the sheet and further cool the sheet.
[0018]
At the stage of crimping and heating, the piston bearing 4 made of tetrafluoroethylene resin is deformed as shown in FIG. 4 and engages with each engaging groove 2 and its outer peripheral surface is formed into a cylindrical shape. When a predetermined time elapses, a certain amount of elastic recovery (elastic recovery) occurs in the radial direction, that is, in the thickness direction, and as a result, the outer peripheral surface of the piston bearing 4 as shown in FIGS. Concavities and convexities occur, and the raised portions 8 that are convex portions are generated on the outer periphery of each engagement groove 2. The raised portion 8 has an annular shape corresponding to the engagement groove 2 being annular, and has a substantially wedge-shaped cross section corresponding to the tapered groove bottom portion 3. Therefore, even if post-processing is not performed on the outer peripheral surface of the piston bearing 4, it is possible to form the raised portion 8 having a substantially wedge-shaped cross section, which is a protrusion effective in preventing the lubricating oil from flowing into the compression chamber.
[0019]
【The invention's effect】
The present invention has the following effects.
[0020]
That is, according to the manufacturing method of the piston bearing according to claim 1 of the present invention including the above steps, the groove bottom portion of the engaging groove is formed in a tapered shape when the engaging groove is provided on the outer peripheral surface of the piston body. When a resin-made piston bearing is attached to the outer peripheral surface of the piston body by pressure bonding, when the elastic return (elastic recovery) occurs after mounting, a plurality of raised portions are generated on the outer peripheral surface of the bearing, and this raised portion is a tapered shape at the bottom of the groove Corresponding to the cross-sectional wedge shape. Therefore, even if post-processing is not performed on the outer peripheral surface of the bearing, a protruding portion having a wedge shape in section, which is a protrusion effective in preventing the lubricating oil from flowing into the compression chamber, can be formed.
Further, in the piston bearing manufactured by the above manufacturing method, a seal lip provided at one end of the piston bearing has a sealing action in one direction and a plurality of wedge-shaped cross sections provided on the outer peripheral surface of the piston bearing. In order for the raised portion to have a sealing action in the opposite direction, a sealing property in both directions on the outer periphery of the piston is realized. Therefore, when this piston bearing is incorporated in a compressor, it is possible to prevent air leakage and effectively prevent lubricating oil from flowing into the compression chamber. Further, since the inner peripheral surface of the annular engaging portion formed integrally with the inner peripheral surface of the piston bearing is raised from the groove bottom portion of the engaging groove, excellent cushioning properties are exhibited.
[0021]
[Brief description of the drawings]
1 is a cross-sectional view of the main part of a piston bearing according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is a model view of a raised portion of the piston bearing. Cross-sectional view of the main part showing a state during production [FIG. 5] Cross-sectional view of the main part of the conventional piston bearing [FIG. 6] FIG. 5 is a partially enlarged view of FIG.
DESCRIPTION OF SYMBOLS 1 Piston main body 2 Engagement groove | channel 2a, 3a Groove bottom part 2b, 3b Side wall part 3 Tapered groove | channel 4 Piston bearing 5 Seal lip 6 Tapered engagement part 7 Engagement part 7a Inner peripheral surface 8 Raised part 8a, 8b Slope 9 Cylinder tube

Claims (1)

A resin-made piston bearing (a plurality of annular engagement grooves (2) are attached to the outer peripheral surface of a piston body (1) arranged in the axial direction by pressure bonding, and a seal lip (5) is provided at one end of a cylinder. 4)
A plurality of annular ridges (8) having a wedge shape in cross section are provided side by side in the axial direction on the outer peripheral surface of the piston bearing (4), and the ridges (8) have a pair of axially inclined surfaces (8a) (8b). An inclination angle (θ ₁ ) of the inclined surface (8a) on the seal lip (5) side is set smaller than an inclination angle (θ ₂ ) of the inclined surface (8b) on the opposite side,
An annular engagement portion (7) that engages with the engagement groove (2) is integrally formed on the inner peripheral surface of the piston bearing (4), and the inner peripheral surface (7a) of the engagement portion (7). In the method of manufacturing the piston bearing (4), which is lifted from the groove bottom (2a) of the engagement groove (2),
A plurality of annular engagement grooves (2) are arranged in the axial direction on the outer peripheral surface of the piston body (1), and the groove bottom (2a) of the engagement groove (2) is relatively shallow on the seal lip (5) side. Form a relatively deep taper on the opposite side,
A piston bearing (4) made of resin is attached to the outer peripheral surface of the piston body (1) by pressure bonding,
A plurality of annular ridges (8) corresponding to the engagement grooves (2) are generated on the outer peripheral surface of the piston bearing (4) by elastic return of the piston bearing (4) after mounting,
The method for manufacturing a piston bearing, wherein the cross-sectional shape of the raised portion (8) exhibits a wedge shape corresponding to the tapered shape of the groove bottom portion (2a).

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