JPH0481074B2 - - Google Patents

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, in order to improve sealing performance, wear resistance, and slidability, as shown in FIG.
A groove 102 was provided on the outer peripheral surface of the piston, and a cylindrical piston ring 103 was mounted in this groove 102. This piston ring 103 was molded from a steel plate coated with tetrafluoroethylene resin (hereinafter referred to as PTFE), nylon, phenol resin, or the like.

(Problems to be solved by the invention) By the way, regarding the above-mentioned structure of the conventional example,
When using a steel plate coated with PTFE, the friction coefficient of the sliding surface is small because the sliding occurs through the PTFE, but the contact surface pressure increases due to the high elastic modulus of the steel plate, which increases the sliding resistance of the piston. The problem was that it was not possible to significantly reduce the Furthermore, when using materials such as nylon or phenolic resin, the elastic modulus is lower than when using steel plates, and the contact surface pressure is lower, but the coefficient of friction is higher than that of PTFE, resulting in greater sliding resistance. There was a problem.

In addition, since there is a gap between the width of the piston ring 103 and the groove width, the piston ring 103 is connected to the piston body 10 when the reciprocating movement of the piston is reversed.
1, the piston ring 103
There was a problem in that the groove 102 hit the side wall of the groove 102 and produced a sound.

Therefore, this invention forms a single PTFE piston ring with self-lubricating and contracting properties on the outer circumferential surface of the piston body, thereby reducing contact surface pressure and sliding resistance, as well as improving the relationship between the piston body and the piston ring. The object of the present invention is to provide a shock absorber piston that is highly fixed and prevents relative movement between a piston ring and a piston body during sliding, and also provides a simple manufacturing method and a simple manufacturing device. With the goal.

(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. The engagement means is made up of a plurality of engagement grooves provided in the axial direction, and a tapered groove that is deeper than the engagement groove and has a tapered surface provided at the end in the axial direction. , the piston ring has a bent portion at one end that engages with the tapered groove.

The method for manufacturing a shock absorber piston of the present invention includes the steps of crimping and attaching a seat to an engagement groove provided on the outer periphery of a piston body through a sheet crimping means;
A step of pressing and bending one end of the sheet to engage a tapered groove provided on the outer periphery of the piston body, a step of press-fitting the piston body with the sheet attached to the outer periphery into a heating cylinder and heating the sheet, and a step of heating the sheet. and a step of cooling the sheet attached to the main body.

The shock absorber piston manufacturing apparatus of the present invention is provided on the outer periphery of the piston body by a conical holding means for holding a seat attached to the piston body, and a press-fitting jig for press-fitting the seat into the outer circumferential surface of the holding means. a sheet pressing means for locking the sheet in the engagement groove formed by the piston body; a means for pressing and bending one end of the sheet to engage the tapered groove on the outer periphery of the piston body; and heating for internally heating the sheet held by the piston body. It consists of a cylinder and a cooling means for cooling a seat attached to the piston body.

(Example) The present invention will be explained below based on the illustrated example. FIG. 1 shows an embodiment of a shock absorber piston according to the present invention. It consists of a piston ring 2 made of PTFE fitted to the surface. An engagement groove 3 is formed on the outer peripheral surface of the piston body 1 over the entire circumference in the circumferential direction.
A plurality of tapered grooves 31 are provided in the axial direction, and a tapered groove 31 having a tapered surface deeper than the engagement groove 3 is provided at the upper end in the axial direction.

The piston ring 2 has a cylindrical shape, and has an annular projection 2a formed on the inner circumferential surface following the shape of the engagement groove 3.
... are provided, and the annular projections 2a, ... are engaged with the engagement grooves 3, .... Further, a bent portion 2b is provided at one end of the piston ring 2, and this bent portion 2b is engaged with a tapered groove 31.

In the shock absorber piston configured as described above, the piston ring 2 is made of PTFE, so the friction coefficient of the sliding surface is low. Furthermore, the elastic modulus is low and the contractility is good, so the contact surface pressure is small.
Sliding resistance is low. Also, 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 projections 2a, ... of the piston ring 2 are fitted into the grooves 3, ... extending perpendicularly to the sliding direction of the piston. Therefore, the force applied to the piston ring 2 is borne by the side surfaces of each groove 3, . Further, the bent portion 2b at one end of the piston ring 2 is formed into a tapered groove 31 deeper than the engagement groove 3.
Since the piston ring 2 is engaged with the piston ring 2, the piston ring 2 is difficult to peel off during sliding, and the sealing performance is stabilized.

Furthermore, the annular projection 2a of the piston ring 2 is
Since it is in close contact with the engagement groove 3 of the piston body 1,
The contact area between the piston ring 2 and the piston body 1 is wide, and as a result, even if a lateral load is applied to the piston ring 2 from the cylinder wall surface when the piston is sliding,
The load per unit area applied to the piston ring 2 is small. Therefore, the deformation of the piston ring 2 due to the lateral load is small, and the amount of axial eccentricity of the piston is reduced.

2 and 3 show other embodiments of the shock absorber piston of the present invention. In the case of Figure 2,
The lower end of the piston ring 2 is expanded and the skirt portion 4 is
is formed. With such a configuration, it functions as a seal ring that seals the sliding portion during sliding. Therefore, there is no need to attach a separate seal ring to improve sealing performance as in the conventional case.

In the case of Fig. 3, wavy irregularities are provided in the circumferential direction of the skirt portion 4 to weaken the rigidity of the piston body 1 in the radial direction, thereby reducing the contact surface pressure of the skirt portion 4 and reducing sliding resistance. It shows.

In this embodiment, the engagement groove 3 and the tapered groove 31 are provided on the outer peripheral surface of the piston body to engage with the annular protrusion 2a provided on the inner peripheral surface of the piston ring 2. A mating projection may be provided to engage 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, in which a piston body supply means 6 for supplying the piston body 1 to a predetermined position on the turntable 5 is installed around the turntable 5, and a piston body supply means 6 is attached to the piston body 1. A taper jig supplying means 8 for assembling a taper jig 7 which is a conical sheet holding means for holding a PTFE sheet 9 to be used, a heating cylinder 10 for storing and heating the PTFE sheet 9 made of tetrafluoroethylene resin, and a heating cylinder 10 Sheet attachment means 11 that takes out the PTFE sheet 9 and attaches it to the taper jig 7; Sheet crimping means 12 that crimps the PTFE sheet 9 to the outer periphery of the piston body 1 via the taper jig 7; and the PTFE sheet 9 that is crimped to the piston body 1. crimping means 13 which swages a bent portion 2b provided at one end of the PTFE sheet 9 as a means for engaging with the outer circumferential surface of the piston body 1 and fits into a tapered groove 31 provided at the upper end in the axial direction of the outer circumferential surface of the piston body 1; The outer periphery of the PTFE sheet 9 is attached to the piston body 1.
A heating cylinder 14 is disposed to press the PTFE sheet 9 inward in the radial direction to form the inner circumferential surface of the PTFE sheet 9 into a shape that follows the outer circumferential surface of the piston body 1.

Six mounting stands 15 for the piston body 1 are provided on the turntable 5 at equal intervals in the circumferential direction, and the turntable 5 is moved counterclockwise in the figure so as to overlap each mounting stand 15,... It rotates intermittently by 60 degrees. Here, each mounting table 1
5, the piston body supply means 6
The position supplied by the station A is the first station A, and the second station B and the third station are
Station C, fourth station D, fifth station E, and 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.
It is adapted to be pushed out to a mounting table 15.

A taper jig 7 is attached to the piston body 1 placed on the mounting table 15. As shown in FIG. A portion 18 is formed. Furthermore, a pin 20 extending downward is formed on the lower end surface 19, and the pin 20 is inserted into the through hole 1a of the piston body 1. Taper jig 7
The pin 20 is longer than the piston body 1, and the push rod 1, which will be described later, is attached to the mounting table 15.
It is inserted into the insertion hole 15h formed in the piston body 5c and attached to the piston body 1. This taper jig 7
The diameter D of the lower end surface 19 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, which is larger than the outer diameter of the piston body 1, protrudes downward. The annular protrusion 21 is configured to fit into the upper end surface of the piston body 1.

Next, the second station B is provided with a heating cylinder 10 that houses the PTFE sheet 9 shown in FIG. The heating cylinder 10 has a cylindrical shape with a bottom, and a band heater 10a is wound around the outer periphery to heat the PTFE sheet 9 inside to soften the PTFE sheet 9 and improve moldability. The PTFE 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 is made of PTFE with negative pressure inside.
A vacuum chuck 11a that sucks sheets 9 one by one, a cylinder 11b that moves the vacuum chuck 11a up and down, and a cylinder 1 that moves the vacuum chuck 11a horizontally.
It consists of 1c.

In addition, the third station C has a PTFE plate attached to the taper jig 7, as shown in detail in Fig. 6.
A seat pressure bonding means 12 is provided that presses the seat 9 downward and press-fits it into the piston body 1. The sheet pressure bonding means 12 is a press-fitting jig 2 in which a plate-shaped body 22a made of rubber or elastic plastic is attached as a pressure means for pressing the piston ring 2 onto the outer peripheral surface of a tapered jig 7 having a circular hole 22b in the center.
2 and a press-fit cylinder 23 that moves the press-fit jig 22 in the vertical direction. The rods 22d, 22d are connected through the insertion holes 24a, 24a provided in the fixed plate 24.
It is slidably inserted in the vertical direction. The rod tip 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, in which a taper jig 7 is mounted on the fixing plate 24.
A spindle 24b for rotating is provided. The lower ends 22e, 22e of the press-fit jig 22 have rods 22d, 22d.
Rod-shaped bodies 26a, 26 facing each other in a direction perpendicular to
a is slidably attached. Taper jig 7
Pressing members 26c, 26c having PTFE plates 26b, 26b attached to the lower surfaces are attached to the inner ends of the rod-shaped bodies 26a, 26a as a pressing means for pressing the piston ring 2 against the outer peripheral surface of the piston ring 2, Holding members 26c, 26c and rod lower end 2
Spring 26d, 26d between 2e, 22e
is inserted to urge the pressing members 26c, 26c inward.

Next, at the fourth station D, as shown in detail in FIG.
A caulking means 13 is provided to prevent the PTFE sheet 9 from shifting or coming off, and is in contact with the spindle 13a disposed directly above the mounting table 15 and the PTFE sheet 9 press-fitted into the piston body 1. , and a roller 13b that presses the PTFE sheet 9. The roller 13b has a trapezoidal cross section, has an upper base with a larger diameter than the lower base, has an acute angle at the upper end, and is formed along the tapered surface of the tapered groove 31 provided at the upper end of the piston body 1 in the axial direction. 13
The height b is set to be the same as the height of the tapered groove on the upper end side of the outer peripheral surface of the piston body 1. The roller 13b is adapted to be moved in the horizontal direction by a cylinder or the like (not shown).

Next, as shown in FIG. 10, a taper jig supply means 8 is disposed at the fifth station E.
It is equipped with a chuck 8a at the tip of the rod that chucks the gripping part 18 of the head of the taper jig 7, and consists of a cylinder 8b that is movable in the vertical direction and a cylinder 8e that holds and moves the cylinder 8b in the horizontal direction. The removed taper jig 7 is transported to the piston body 1 of the first station A and assembled.

Next, at the sixth station F, as shown in FIG. 11, a heating cylinder 14 is installed above the mounting table 15.
A cooling cylinder 27 is provided, and the heating cylinder 14 and the cooling cylinder 27 have the same diameter and are formed coaxially and integrally with a heat insulating material 28 interposed therebetween. A band heater 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 flowed inside the cooling jacket 24a, and the temperature is controlled at a certain set temperature similarly to the heating cylinder 14.

The inner peripheral surfaces of the heating and cooling cylinders 14 and 27 are 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 is attached to the turntable 5 via a bearing 15a 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 is formed with a stepped portion 15d, which engages with a stepped portion 15e formed in the through hole 15b to prevent it from falling downward. Further, a spring seat 15f is provided at the lower end of the push rod 15c, and a spring 1 is provided between the spring seat 15f and the bearing 15a.
5g is interposed to urge the push rod 15c downward. A cylinder 29 is provided at a lower position of the turntable 5 corresponding to the position where the heating cylinder 14 is provided, which pushes the push rod 15c upward and press-fits the piston body 1 on the mounting table 15 into the heating cylinder 14. There is.

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 supplied to the mounting table 15. Next, the taper jig 7 is attached onto the piston body 1 by the taper jig supply means 8. The turntable 5 rotates counterclockwise in the figure, and the piston body 1 is transported to the second station B. 2nd station B
Now, the heating tube 1 is turned on by the vacuum chuck 11a.
The PTFE sheet 9 inside the cylinder 11 is adsorbed and
It is conveyed to the upper part of the taper jig 7 by the cylinder 11b, and is attached to the taper jig 7 in a horizontal state by the cylinder 11b. Then, the turntable 5 rotates and the piston body 1 is transported to the third station C. At the third station C, the taper jig 7 is fixed by a presser cylinder 25 so that it does not move. Then, the plate-shaped body 22a is inserted by the press-fit cylinder 23.
is pushed down via the rods 22d, 22d. 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 22 of the plate-shaped body 22a is inserted as shown in FIG.
b is expanded along the outer peripheral surface of the tapered jig 7.
The PTFE sheet 9 is pressed against the outer circumferential surface of the taper jig 7 by the lower surface of the plate-shaped body 22a, and its inner diameter expands while sliding along the outer circumferential surface, gradually being formed into a cylindrical shape, and is pressed against the outer circumferential surface of the piston body 1. It will be installed. The upper end of the piston ring 2 formed from this PTFE sheet 9 is connected to the annular protrusion 21 at the lower end of the taper jig 7.
Since it is at the lower end position, the length L of the annular protrusion 21 is
By adjusting , it becomes possible to position the piston ring 2 on the outer circumferential surface of the piston body 1.
Furthermore, the PTFE sheet 9 is pressed against the outer peripheral surface of the taper jig 7 by the plate-shaped body 22a of the press-fitting jig 22.
As the inner diameter of the PTFE sheet 9 is expanded, even if the outer diameter of the piston body 1 changes due to specifications etc.
This can be done by simply changing the outer diameter of the taper jig 7.
Therefore, in the process of attaching the PTFE sheet 9 to the outer peripheral surface of the piston body 1, the piston body 1
Even if the outer diameter of the jig 7 changes, it is sufficient to simply replace it with a taper jig 7 that matches the diameter.

Further, FIG. 8 shows another embodiment of the sheet pressure bonding means 12, in which the taper jig 7 is rotated by a spindle 24b. The piston body 1 and the mounting table 1 are used to rotate the taper jig 7.
5 is also rotating. In this state, the press-fit cylinder 23
The presser member 2 is attached via the rods 22d and 22d.
Press down 6c and 26c. Pressing members 26c, 26
PTFE c is pressed down along the outer peripheral surface of the taper jig 7 and is rotating together with the taper jig 7.
Contact sheet 9. It is further pushed down and by the spring force of springs 26d, 26d.
The PTFE sheet 9 is pressed against the outer peripheral surface of the taper jig 7, and is gradually and effortlessly formed into a cylindrical shape by the rotation of the PTFE sheet 9 itself.

Next, the piston body 1 to which the PTFE sheet 9 is attached is conveyed to the fourth station D by the rotation of the turntable 5. At the fourth station D, the taper jig 7 is operated by the spindle 13a.
is rotated, and the roller 13b is moved in the horizontal direction using a cylinder or the like to press the upper end of the PTFE sheet 9 attached to the piston body 1, and caulk it into the tapered groove 31 on the upper end side of the piston body 1.

After being crimped, the piston body 1 is transported to the fifth station E by the rotation of the turntable 5. Here, the gripping portion 18 of the taper jig 7 is chucked by the chuck 8a, and the taper jig 7 is removed from the piston body 1 by being lifted by the cylinder 8b. Furthermore, cylinder 8
c, the taper jig 7 is transported to the first station A and attached 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
The rotation of the turntable 5 transports it to the sixth station F. Here, the piston body 1 is pushed up by the cylinder 29 via the push rod 15c of the mounting table 15, and is press-fitted into the heating cylinder 14 through the opening taper portion 14a. The PTFE sheet 9 is softened in the heating cylinder 14, and the outer circumferential surface of the PTFE sheet 9 is pressed in the radial direction, so that the inner circumference of the PTFE sheet 9 enters into the engagement groove 3 on the outer circumferential surface of the piston body. 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, and the heating cylinder 14
It is cooled, solidified, and discharged as it is. 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.
Sliding resistance is further reduced.

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 larger on the upper end side, and the piston ring 2 is formed more on the lower end side than on the upper end side. The outer diameter of the Therefore, by appropriately setting the outer diameter of the PTFE sheet 9, a piston ring with a skirt as shown in FIG. 2 described above can be formed. In addition, in order to form wavy irregularities on the skirt portion 4 as shown in FIG.
As shown in FIG. 2, this is accomplished by providing the opening taper portion 14a of the heating cylinder 14 with wave-like unevenness 4b extending in the axial direction of the heating cylinder 14.

(Effects of the Invention) The shock absorber piston according to the present invention has the above-described configuration and function, and since it is equipped with a piston ring made of PTFE that has self-lubricating and contracting properties, it is different from the conventional steel plate coated with PTFE. The elastic modulus is lower than those made of phenolic resin and nylon, and the contact pressure is lower, reducing sliding resistance.
Since PTFE has a low coefficient of friction, 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 the generation of abnormal noises caused by relative movement.
Furthermore, since the bent portion at one end of the piston ring engages with a tapered groove that is deeper than the engagement groove and has a tapered surface, the piston ring is difficult to peel off during sliding, and the sealing performance is stabilized.

Note that if the piston ring is brought into close contact with the engaging portion on the outer circumferential surface of the piston body, the contact area between the piston and the piston ring will increase, so the deformation of the piston ring due to the lateral load applied from the cylinder wall surface to the piston ring when the piston is sliding will be reduced. This also provides the effect of reducing the amount of shaft eccentricity when the piston slides.

Furthermore, when using the method for manufacturing a shock absorber piston according to the present invention, the piston ring can be directly molded from a flat sheet and can be installed at the same time.
In addition to being extremely easy to manufacture, the yield of piston ring molding is high, and costs can be reduced.

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. In addition, the press-fitting jig provided in the sheet crimping means allows
Since the seat is pressed against the outer peripheral surface of the conical holding means and the inner diameter of the seat is expanded, even if the outer diameter of the piston body changes due to specifications etc., it can be accommodated by simply changing the outer diameter of the conical holding means. . Therefore, even if the outer diameter of the piston body changes during the process of attaching the seat to the outer peripheral surface of the piston body,
It is sufficient to simply replace it with a conical holding means that matches the diameter.

[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. FIG. 7 is a partially cutaway front view of the sheet crimping means of the device shown in FIG. 7; FIG. 7 is a front sectional view showing the vicinity of the taper jig and the piston body in which the PTFE sheet is press-fitted into the piston body by the device shown in FIG. 4; 8 is a partially cutaway front view showing another aspect of the device shown in FIG. 6, FIG. 9 is a partially cutaway front view showing the caulking means of the device shown in FIG. 4, and FIG. 10 is a partially broken front view showing the device shown in FIG. 4. FIG. 11 is a partially cutaway front view of the taper jig supply means of FIG. 4, and FIG.
2 is a front sectional view of the tapered opening of the heating cylinder shown in FIG. 11, and FIG. 13 is a partially cutaway front view of a conventional shock absorber piston. Explanation of symbols, 1... Piston body, 2... Piston ring, 2b... Bent portion, 3... Engagement groove (engaging means), 31... Taper groove (engaging means), 4...
Skirt portion, 5... Turntable, 6... Piston body supply means, 7... Taper jig (sheet holding means), 9... PTFE sheet, 10... Heating cylinder,
DESCRIPTION OF SYMBOLS 11... Sheet supply means, 12... Sheet pressure bonding means, 13... Crimping means, 14... Heating cylinder, 15... Placing table.

Claims (1)

[Claims] 1. A piston ring made of tetrafluoroethylene resin is engaged with and attached to the outer peripheral surface of a piston body provided with an engaging means, and the engaging means is provided in a plurality of strips in the axial direction. The piston ring is comprised of an engaging groove and a tapered groove that is deeper than the engaging groove and has a tapered surface provided at an axial end, and a bent portion that engages with the tapered groove is provided at one end of the piston ring. Characteristic shock absorber piston. 2. A step of crimping and attaching the sheet to an engagement groove provided on the outer periphery of the piston body using a sheet crimping means, and a step of pressing and bending one end of the sheet to engage with a tapered groove provided on the outer periphery of the piston body. A piston for a shock absorber, comprising: a step of press-fitting a piston body with a seat attached to the outer periphery into a heating cylinder to heat the seat; and a step of cooling the seat attached to the piston body. manufacturing method. 3. Locking the seat in the engagement groove provided on the outer periphery of the piston body using a conical holding means for holding the seat attached to the piston body and a press-fitting jig for press-fitting the seat into the outer circumferential surface of the holding means. a sheet crimping means; a means for pressing and bending one end of the sheet to engage a tapered groove on the outer periphery of the piston body; a heating cylinder for internally heating the sheet held by the piston body; and a heating cylinder attached to the piston body. A manufacturing apparatus for a shock absorber piston, comprising a cooling means for cooling a seat.