JPS6182072A - Shock absorber piston and its manufacturing method and device - Google Patents

Abstract

PURPOSE:To prevent a relative movement caused between a piston ring and a piston main unit, by mounting the piston ring of tetrafluoroethylene resin engaging with a peripheral surface of the piston main unit equipping an engaging means. CONSTITUTION:A piston main unit 1 provides both a through hole 1a in a direction of the axial center and plural strips of engaging grooves 3 fully over a peripheral surface of the piston main unit in its circumferential direction. A piston ring 2, being formed in a cylindrical shape and providing on its internal peripheral surface annular protrusions 2a formed profiling a shape of the engaging grooves 3, engages said annular protrusion 2a with the engaging groove 3 of the piston main unit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shock absorber piston used in an automobile suspension system, and a method and apparatus for manufacturing the same.

(Prior Art) Conventionally, in a piston used for a shock absorber, a groove 102 is provided on the outer peripheral surface of a piston body 101 as shown in FIG. 13 in order to improve sealing performance, wear resistance, and sliding performance. A cylindrical piston ring 103 was installed in this groove 102. This piston ring 103 was molded from a steel plate coated with polytetrafluoroethylene resin (hereinafter referred to as PTFE), nylon, phenol resin, or the like.

(Problem that the invention attempts to solve) By the way, in the above-mentioned structure of the conventional example.

Although the number is small, there was a problem in that the contact surface pressure was large υ due to the high elastic modulus of the steel plate, and it was not possible to significantly reduce the sliding resistance of the piston. In addition, when using materials such as nylon or phenolic resin, the elastic modulus is lower than those using steel plates, and the contact surface pressure is lower, but the friction coefficient is higher than that of PTFE, resulting in greater sliding resistance. There was a problem.

Furthermore, since there is a gap between the width of the piston ring 103 and the groove width, the piston ring 103 moves relative to the piston body 101 when the reciprocating motion of the piston is reversed, and the piston ring 103 touches the side wall of the groove 102. There was a problem that it would make a sound when it hit.

Therefore, this invention forms a single PTFE piston ring with self-lubricating and contracting properties on the outer peripheral surface of the piston body, thereby reducing contact surface pressure and sliding resistance.
The purpose of the present invention is to provide a complete piston for a shock absorber that increases the degree of fixation between the piston body and the piston ring and prevents relative movement between the piston ring and the piston body during sliding.
It is also an object of the present invention to provide a simple manufacturing method and a simple manufacturing device.

(Means for Solving the Problems) In order to achieve the above object, the shock absorber piston according to the present invention includes a piston ring made of tetrafluoroethylene resin on the outer peripheral surface of the piston body provided with the engagement means. It consists of parts that are engaged and attached.

The method for manufacturing a shock absorber piston of the present invention is now complete.

The apparatus for manufacturing a shock absorber piston according to the present invention comprises a cooling means for cooling a seat roller attached to a piston body.

(Example 1) The present invention will be explained below based on the illustrated embodiment.
The figure shows an embodiment of a shock absorber piston according to the present invention, and this shock absorber piston includes a cylindrical piston body 1 having a through hole 1a in the axial direction of the piston, and an outer periphery of the piston body 1. It consists of a PTFEff piston ring 2 fitted to the surface.

A plurality of engagement grooves 3 are provided on the outer peripheral surface of the piston body 1 in the axial direction of the piston body 1, and are formed over the entire circumference in the circumferential direction.

The piston ring has a 3μ cylindrical shape, and an annular protrusion 2a formed on the inner peripheral surface following the shape of the engagement groove 3.

... is provided in the annular protrusion 2, ... is an engagement groove 3...In a shock absorber piston configured as above in the R4A set,
Since the piston ring 2 is made of PTFE,
The friction coefficient of the sliding surface is low. Furthermore, the elasticity is low and the shrinkability is good, so the contact surface pressure is small.

Dynamic resistance is low. Furthermore, when the piston is sliding, the piston ring 2 is pulled in the opposite direction to the sliding direction due to sliding resistance, but the annular protrusion 2 a +...
・Groove 3 extending perpendicularly to the sliding direction of the piston
．． ..., the force applied to the piston ring 2 is applied to the 6 grooves 3. Uke is held by the aspect of...

2 and 3 show other embodiments of the shock absorber piston of the present invention. In the case of FIG. 2, the lower end of the piston ring 2 is expanded to form the skirt portion 4. With such a configuration, it functions as a seal ring that seals the sliding portion during sliding. Therefore, it is no longer necessary to install all separate seal rings in order to improve the sealing performance as in the conventional case.

In the case of Fig. 3, the skirt part 40 is provided with wave-like unevenness in the circumferential direction, which weakens the rigidity of the piston body 10 in the radial direction, and reduces the contact surface pressure of the skirt part 4, thereby reducing sliding resistance. It shows.

In this embodiment, an engagement groove 3 is provided on the outer peripheral surface of the piston body.
An annular protrusion 2 provided on the inner peripheral surface of the piston ring 2
Although the piston ring is engaged with the piston ring by providing an engaging protrusion on the outer circumferential surface of the piston body, the piston ring may be engaged with the piston ring.

Next, an apparatus and method for manufacturing a shock absorber piston having the above-described structure will be explained.

FIG. 4 shows a conceptual diagram of the manufacturing apparatus of the present invention,
6. Piston body supply means for supplying a 1 ft piston body to a predetermined position of the turntable 5 in a circumferential recess of the turntable 5. Taper jig supply means 8 for assembling the taper jig 7, which is a sheet holding means for holding the PTFB sheet 9 attached to the piston body 1. PTF of tetrafluoroethylene resin
A heating cylinder 10 that stores and heats the E-sheet 9; and a sheet attachment means 11 that takes out the PTFE sheet 9 from the heating cylinder 10 and attaches it to the taper jig 7. PTFE sheet 9 with taper jig 7
a sheet crimping means 12 which presses the PTFE sheet 9 onto the outer periphery of the piston body 1 via a crimping means 13 which crimps the PTFE sheet 9 which is crimped onto the piston body 1 and fits it into the engagement groove 3 provided on the outer periphery of the piston body 1. A heating cylinder 14 is provided that presses the outer circumference of the PTFE sheet 9 inward in the radial direction of the piston body 1 so that the entire inner circumferential surface of the PTFE sheet 9 forms a shape that follows the shape of the outer circumferential surface of the piston body 1. There is.

On the turntable 5, six mounting tables 15 for the piston body 1 are provided at equal intervals in the circumferential direction.
5. The turn cheagle 5 is intermittently rotated by 60' in the counterclockwise direction in the figure so as to overlap with the positions of . Here, regarding the stop position of each mounting table 15, the position supplied by the piston body supply means 6 is defined as the first station A.

Counterclockwise in the figure are a second station B, a third station C, a fourth station D, a fifth station E, and a sixth station F.

The equipment for each step will be explained in detail below. First, the piston body supply means 6 consists of a hydraulic cylinder 16 arranged in the radial direction of the turntable 5.
Piston body 1 that is inserted into the front of rod tip 17 of 6
is pushed out to the mounting table 15 of the turntable 5.

A taper jig is attached to the gibbon main body placed on the mounting table 151C, as shown in FIG.

The taper jig 7 has a conical shape, and a cylindrical or square-shaped clamping portion 18 is formed at its upper end.

Further, on the lower end surface 19, there is a bevel 720 extending downward.
is formed, and the pin 20 is inserted into the through hole 1a of the piston body 1. The pin 20 of the taper jig 7 is longer than the piston body 1.

It is inserted into an insertion hole 15h formed in a push rod 15c (described later) attached to the mounting table 15, and is assembled to the piston body 1. The diameter of the lower end surface 19 of this taper jig 7 is formed to be slightly larger than the outer diameter d of the piston body 1, and the outer peripheral edge of the lower end surface of the taper jig 7 is larger than the outer diameter of the piston body 1. , an annular protrusion 21 that protrudes downward. 2, the annular protrusion 21 fits into the upper end of the piston body 1.

Next, at the second station B, the PTF shown in Figure 5 is installed.
A heating cylinder 10 for storing the E-sheet 9 is provided. The heating cylinder 10 has a cylindrical shape with a bottom, and a band heater 10a is attached to the outer periphery.
is wound and heats the internal PTFE sheet 9 to form a PTF
E-sheet 9 is made soft to improve moldability. PTF
The E-sheet 9 is disc-shaped and has a hole 9a formed in the center.

The sheet member attachment means 11 has a cylindrical shape with a bottom that can be inserted into the heating cylinder 10, and the inside is made negative and positive so that the PTFE sheet 9 can be attached to the PTFE sheet 9.
A vacuum chuck 11a that picks up sheets one by one, a cylinder llb that moves the vacuum chuck lla'i up and down,
It further includes a cylinder 11c for horizontally moving the vacuum chuck lla.

Further, as shown in detail in FIG. 6, the third station C is provided with a sheet crimping means 12 that presses the PTFE sheet 9 attached to the taper jig 7 downward and press-fits it into the piston body 1. The sheet pressure bonding means 12 has a circular hole 22b in the center. It consists of a press-fitting jig 22 to which a plate-like body 22ae of rubber or elastic plastic is attached, and a press-fitting cylinder 23 that moves the press-fitting jig 22 in the vertical direction. The support plate 22c and the rods 22d and 2 are arranged opposite to each other.
It is constructed by connecting through 2 d.

The rods 92d and 92d are inserted into insertion holes 24a and 24a provided in the fixed plate 24 so as to be slidable in the vertical direction. A rod end portion of the cylinder 23 is fixed to the support plate 22c. Further, the fixing plate 24 is provided with a holding cylinder 25 for holding down the tapered jig 7 for holding the tapered jig 7 therein.

FIG. 8 shows another embodiment of the sheet pressure bonding means 12.
A spindle 24b for making the taper jig 7'too= is disposed on the fixed plate 24.

The lower ends 22e of the rods 22d, 22d of the press-fit jig 22
, 22e are slidably attached to rod-shaped bodies 26a, 26a that face each other in a direction perpendicular to the rods 22d, 22d. At the inner ends of the rod-shaped bodies 26a, 26a, there are plates 26b, 26 made of PTFE on the lower surface.
The presser members 26c, 26c to which b is attached are attached, and springs 26d, 26d are installed between the presser member 26c'+26c and the rod lower end portions 22e, 22e.
is inserted to urge the pressing members 26c, 26c inward.

Next, as shown in FIG. 9 in detail, the fourth station DK is provided with a caulking means 13 for preventing the PTFE sheet press-fitted into the piston body 1 from shifting or coming off, and is located directly above the mounting table. The spindle 13a arranged in
and a roller 13b that presses the PTFE sheet 9 in close contact with the PTFE sheet 9 press-fitted into the piston body 1. The roller 13b has a trapezoidal cross section, the upper base has a larger diameter than the lower base, and the upper end corner is formed at an acute angle. It is set to the same height as 3. roller 13
b is adapted to be moved in the horizontal direction by a cylinder or the like (not shown).

Next, a taper jig supply means 8 is disposed at the fifth station E, and a chuck 8af that chucks the gripping portion 18 of the head of the taper jig 7 is provided at the tip of the rod, and a cylinder 8b that is movable in the vertical direction is provided. Then, the removed taper jig 7 is conveyed to the piston body 1 of the first station A and assembled together with the cylinder 8c which holds the cylinder 8be and moves it in the horizontal direction.

Next, in the sixth station F, as shown in FIG. 11, a heating cylinder 14 and a cooling cylinder 27 are arranged above the mounting table 15, and the heating cylinder 14 and the cooling cylinder 27 have the same diameter and are coaxial. are integrally formed with a heat insulating material 28 in between.

A pan dome 14a is wound around the heating cylinder 14, and is connected to a temperature control device (not shown) to control the temperature at a set temperature. Further, the cooling cylinder 27 is provided with a cooling jacket 27a, and a heat medium such as water or nitrogen gas is allowed to flow inside the cooling jacket 27a, and the temperature is controlled at a certain temperature similarly to the heating cylinder 14.

The inner peripheral surface of the heating and cooling cylinder 14.27 is precisely finished by honing.

When producing products with different outer diameters, if heating cylinders and cooling cylinders of predetermined dimensions are made in advance, the heating and cooling cylinders can be replaced in a short time.

The mounting base 15 of the turntable 5 has a bearing 15at.
- It is attached to the turntable 5 through the screw and is rotatable. A through hole 15b is provided in the center of the mounting table 15, and a push rod 15c is inserted therethrough so as to be slidable in the vertical direction. The upper end of the push rod 15c has a large diameter and a stepped portion 15d, which engages with a stepped portion 15e formed in the through hole 15b to prevent it from falling downward. Furthermore, push rod 15c
A spring seat 15f is provided at the lower end of the spring seat 15.
A spring 15g is interposed between f and the bearing 15a to bias the push rod 15ct downward. At a lower position corresponding to the position where the heating cylinder 14 of the turntable 5 is provided, a cylinder 29 is provided which pushes the push rod 15ct upward and press-fits the piston body 1t on the mounting table 15 into the heating cylinder 14. ing.

Next, the operation of such a device will be explained.

At the first station, the piston body 1 is pushed out onto the turntable 5 by the cylinder 16 and placed on the mounting table 1.
5. Next, the taper jig 7 is attached onto the piston body 1 by the taper 9 jig supply means 8. The turntable 5 rotates counterclockwise in the figure, and the piston body 1 is transported to the second station B. At the second station B, the vacuum chuck lla is heated by the heating cylinder 1.
The PTFE sheet 9 inside the cylinder 11 is adsorbed and transported to above the cheek jig 7 by the cylinder llc.
b is attached to the taper jig 7 in a horizontal state.

Then, the turntable 5 rotates and the piston body 1
It is transported to the third station C. 3rd station C
Now, the taper jig 7 is fixed by the presser cylinder 25 so that it does not move.

Next, the rod-shaped body 22a is inserted into the rod 2 through the press-fit cylinder 23.
2d, 22dt-Push down through.

The plate-shaped body 22a is inserted into the taper jig 7 through the hole 22b, and as the press-fit cylinder 23 is lowered, the hole 22b of the plate-shaped body 22a is inserted into the outer peripheral surface of the taper jig 7, as shown in FIG. will be expanded along. The PTFE sheet 9 is a plate-shaped body 22a
The lower surface of the taper jig 7 is pressed against the outer circumferential surface of the taper jig 7, and the inner diameter expands while sliding along the outer circumferential surface, gradually forming a cylindrical shape, and is attached to the outer circumferential surface of the piston body 1. The upper end of the piston ring 2 formed from this PTFE sheet 9 is the lower end position of the annular protrusion 21 at the lower end of the taper jig 7, so by adjusting the length of the annular protrusion 21, the outer peripheral surface of the piston body 1 can be adjusted. The upper piston ring 2 can be positioned.

FIG. 8 shows another embodiment of the sheet pressure bonding means 12, in which case the tapered jig 7t is rotated by a spindle 24b. When the taper jig 7 is rotated, the piston body 1 and the mounting table 15 are also rotated. In this state, the pressing member 26c is pressed by the press-fitting cylinder 23 via the rods 22d, 22d.

Press down 26c. Pressing members 26c, 26. c is pressed down along the outer peripheral surface of the taper jig 7.

It comes into contact with the PTFE sheet 9 which is rotating together with the taper jig 7. The spring 26d is further pressed down.

The PTFE sheet 9 is pressed against the outer peripheral surface of the taper jig 7 by the spring force 26d, and is gradually and effortlessly formed into a cylindrical shape by the rotation of the PTFE sheet 9 itself.

Next, by rotating the turntable 1, the PTFE sheet 9 is
The piston body 1 with the attached piston body 1 is transported to the fourth station D. 4th stage: In 17I) ic, the cheek jig 7 is rotated by the spindle 13a, and the roller 13bi is moved in the drying direction by a cylinder or the like to press the upper end of the PTFE sheet 9 attached to the piston body 1, and the piston It is crimped into the engagement groove 3 on the upper end side of the main body 1.

After being crimped, the piston body 1 is attached to the turntable 50
It is transported to the fifth station E by rotation. Here, the gripping part 18 of the cheek jig 7 is chucked by the chuck 8a, and the taper P jig 7 is removed from the piston body 1 by lifting it with the cylinder 8b. Furthermore, the taper jig 7 is conveyed to the first station A by the cylinder 8C, and is assembled to the piston body 1 supplied by the piston body supply means 6.

The piston body 1 from which the taper jig 7 has been removed is conveyed to the sixth station F by the rotation of the turntable 5. Here, the piston body 1 is the push rod 15c' of the mounting table 15.
It is pushed up by the cylinder 29 through the opening taper portion 14a and is press-fitted into the heating cylinder 14 through the opening taper portion 14a. The PTFE sheet 9 becomes soft inside the heating cylinder 14, and the outer peripheral surface of the PTFE sheet 9 is pressed in the radial direction.
The inner circumference of the PTFE sheet 9 locks the outer circumferential surface of the piston body @
Enter into 3. When the next piston body 1 is further press-fitted, it is pushed upward by the next piston body 1 and is sent upward one by one by the length of the piston body 1 in the axial direction. After passing through the heating cylinder 14, it is sent to the cooling cylinder 27, where it is cooled, hardened, and discharged in the same state as it was formed in the heating cylinder 14. Since the inner circumferential surfaces of the heating cylinder 14 and the cooling cylinder 27 are polished to a mirror finish by honing, the outer circumferential surface of the piston ring 2 of the molded shock absorber piston becomes smooth, further reducing sliding resistance. .

In addition, since the inner diameter of the plate-shaped PTFE sheet 9 is expanded with the taper jig 7 and attached to the piston body 1, the elongation rate is greater on the upper end side, and the piston ring on the lower end side is molded as well as the upper end side. The outer diameter of 2 is thicker. Therefore, by appropriately setting the outer diameter of the PTFE sheet, a piston ring with a skirt as shown in FIG. 2 can be formed. In addition, in order to completely form the wavy unevenness on the skirt portion 4 as shown in FIG. This is achieved by providing wave-like unevenness 14bt extending in the axial direction.

(Effects of the Invention) The shock absorber piston according to the present invention has the above-described structure and function, and has self-lubricating and contracting properties.
Since the TFE-backed piston ring is installed, the elastic modulus is lower than the conventional one made of PTFEt-coated steel plate, and the contact surface pressure is reduced, reducing sliding resistance. Since PTFE has a lower coefficient of friction than nylon, it has the effect of significantly reducing sliding resistance.

In addition, since the piston ring is engaged with the engagement means on the outer peripheral surface of the piston body, the degree of fixation between the piston body and the piston ring is high, and there is no relative movement between the piston body and the piston ring when sliding. This provides the effect of preventing abnormal noises caused by relative movement.

In addition, when using the method of manufacturing a piston for a shock absorber according to the present invention, the piston ring can be directly molded from a flat sheet and can be installed at the same time, making it extremely easy to manufacture and reducing the yield of molding the piston ring. The advantage is that it is possible to reduce costs.

Further, when using the apparatus for manufacturing a shock absorber piston according to the present invention, the effect that the shock absorber piston can be manufactured extremely easily can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a shock absorber piston according to an embodiment of the present invention, FIGS. 2 and 3 are partially cutaway front views showing other aspects of the piston of FIG. 1, and FIG. 5 is a conceptual diagram of a shock absorber piston manufacturing apparatus according to an embodiment of the present invention, FIG. 7 is a partially cutaway front view of the sheet crimping means of the apparatus shown in FIG. 7; FIG. 8 is a partially cutaway pressure surface view showing another aspect of the device shown in FIG. 6, FIG. 9 is a partially broken front view showing the caulking means of the device shown in FIG. 4, and FIG. 10 is a partially cutaway front view of the device shown in FIG. 4. A partially cutaway pressure surface view of the taper jig supply means, FIG. 11 is a partially cutaway pressure surface view showing the vicinity of the heating cylinder and cooling cylinder of the device in FIG. 4, and FIG. 12 is a tapered opening of the heating cylinder in FIG. 11. FIG. 13 is a partially cutaway front view of a conventional shock absorber piston. Explanation of symbols 1... Piston body 2... Piston ring 3... Engagement groove (engaging means) 4... Skirt portion 5...
・Turntable 6...Piston body supply means 7...Teno jig (seat holding means) 9...PT
FE sheet 10...Heating cylinder 11...Sheet supply means 12...Sheet pressure bonding means 13., crimping means 14...Heating cylinder 15...Placement table Patent applicant Japan Oil Seal Chestnut Co., Ltd. agent Japanese Patent Attorney Kazunobu Sera:'jjj,,>:, Figure 9, Figure 10, Figure 11, Figure 12, Figure 13, Amendment to Kotsugi (Mouse) June 28, 1985

Claims (3)

[Claims] (1) A shock absorber piston characterized in that a piston ring made of tetrafluoroethylene resin is engaged and attached to the outer peripheral surface of a piston body provided with an engagement means. (2) a step of attaching the seat to the engaging portion on the outer periphery of the piston body via a seat pressure bonding means; a step of press-fitting the piston body with the seat attached to the outer periphery into a heating cylinder to heat the seat; and further a step of heating the seat. 1. A method for producing a shock absorber piston, comprising the steps of: cooling a seat attached to the seat; and then taking it out. (3) a holding means for holding a seat attached to the piston body, a seat pressure bonding means for locking the seat to an engaging portion on the outer periphery of the piston body, and a heating cylinder that internally heats the seat held by the piston body; 1. An apparatus for manufacturing a shock absorber piston, comprising a cooling means for cooling a seat attached to the piston body.