JP3562082B2 - Molding method of synthetic resin piston - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of molding a synthetic resin piston, and more particularly, relates to method of molding a synthetic resin piston for use in a master cylinder to be used in the brake device and a clutch device for a vehicle.
[0002]
[Prior art]
Molding method of a conventional synthetic resin piston, the piston is a molding of the same piston having a substantially equal flange portion to the diameter of the cylinder bore of the cylinder body that is inserted slidably, extension of the axis of the piston A piston made of a synthetic resin material is molded by filling a molding die having a resin injection hole on a line with a resin from the resin injection hole.
[0003]
Generally, when the synthetic resin piston resin molding (molding by a thermoplastic resin), by injection toward the resin in the axial direction of the piston, roundness and size was uniformly filled in a mold Improving accuracy is performed. Further, the strength of the resin is improved by mixing glass fibers.
[0004]
[Problems to be solved by the invention]
However, in the method of molding a synthetic resin piston described above, a conventional state of the resin in the axial section of the piston 100 in the vicinity of the flange portion 101 of the piston 100 which is molded by the molding method of the synthetic resin piston 8 As described above, since the direction in which the injected resin flows is the axial direction of the piston, the resin and the glass fiber are cooled and solidified substantially in the axial direction. Generally the resin is one that shrinks in a direction perpendicular to the direction of the hardened cold flow of resin, therefore, the flange portion 101 and in particular approximately equal to the diameter of the cylinder bore, such as dimensional accuracy is required If the resin shrinks in the vicinity, the piston 100 may rattle in the cylinder hole, which may hinder smooth sliding of the piston 100.
[0005]
Further, when a thick portion is formed in a resin molded product, it causes voids, cracks, and the like.
[0006]
It is a technical object of the present invention to provide a resin piston which secures dimensional accuracy by preventing shrinkage of a resin particularly at a place where dimensional accuracy is required, and further prevents the occurrence of voids and cracks. It is assumed that.
[0007]
[Means for Solving the Problems]
In order to solve the above technical problems, a piston forming, with a resin injection hole on the extension of the axis of the piston, the forming mold with the projections of the vertical rod-like with respect to said axis, by filling the resin from the resin injection hole, to constitute a method of molding a synthetic resin piston for forming a piston made of a synthetic resin material.
[0008]
Preferably, the piston has a flange portion substantially equal to a diameter of a cylinder hole of a cylinder body into which the piston is slidably inserted, and the rod-shaped protrusion is provided on the flange of the molding die. method of molding a synthetic resin piston is provided in the vicinity of the portion for molding the parts is desirable.
[0009]
Preferably, the cylinder body is a cylinder body of the vehicle master cylinder, said piston forming method of the synthetic resin piston having the flange portion at two locations of the front side and the rear side is preferable.
[0010]
Method of molding a synthetic resin piston according to claim 1, by injection toward the resin injection hole of the molding die a resin in the axial direction of the piston, the resin flows in the axial direction of the piston, the mold The direction of flow of the resin is dispersed in the radial direction of the piston by hitting the rod-shaped protrusion , and further, the dispersed resin gradually flows out in the axial direction of the piston and merges with the flow of the subsequent resin in the radial direction of the piston. As a result, the resin is agitated, and thereafter, the resin passes near the rod-shaped protrusion, flows out in the axial direction of the piston, and the inside of the molding die is filled with the resin.
[0011]
Method of molding a synthetic resin piston according to claim 2, in addition to the operation of claim 1, molding the resin is injected in the axial direction of the piston during the molding, the resin flows in the axial direction of the piston, the flange portion By hitting the rod-shaped protrusion of the molding die provided in the vicinity of the part to be formed, the direction of flow of the resin is dispersed in the radial direction of the piston, and flows into the portion of the molding die where the flange is molded. Further, the dispersed resin gradually flows in the axial direction of the piston, and merges with the subsequent flow of the resin in the radial direction of the piston, whereby the resin is stirred.
[0012]
Method of molding a synthetic resin piston according to claim 3, in addition to the operation of claim 2, the injected resin from the resin injection hole flows in the axial direction of the piston, provided in the vicinity of the portion for molding the flange portion of the front side By hitting the rod-shaped protrusion in the formed molding die, the flow direction of the resin is dispersed in the radial direction of the piston, and flows into a portion of the molding die where the front flange portion is formed. Further, the front side by the resin that has flowed into the portion for molding the front side flange portion of the molding die is dispersed flows out in the axial direction of the piston gradually merges with the flow of resin toward the radial direction of the subsequent piston The resin in the vicinity of the rod-shaped protrusion provided near the portion where the flange is formed is agitated.
[0013]
The resin that has passed near the rod-shaped projections begins to flow in the axial direction of the piston, and the direction in which the resin flows in the direction of the piston hits the rod-shaped projections of the molding die provided near the site where the rear flange is formed. distributed radially, it flows into the portion for molding the rear side flange portion of the molding die. Further, the rear side by a resin that has flowed into the portion for molding the rear side flange portion of the molding die is dispersed flows out in the axial direction of the piston gradually merges with the flow of resin toward the radial direction of the subsequent piston The resin in the vicinity of the rod-shaped protrusion provided near the portion where the flange is formed is agitated.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the embodiment of the present invention will be described specifically.
[0015]
Figure 1 is a cross-sectional view of a mold 1 for molding of synthetic resin piston 2 of the present embodiment, FIG. 2 is a sectional view of the synthetic resin piston 2, Fig. 3 is a top view of FIG. 2 , and the small holes 8, 9 in FIG. 4 der model diagram showing a state of the resin 40 and glass fibers 41 in the radial section of the piston 2 on the front side flange portion 4 of the piston 2 Rutotomoni, 4 the piston 2 FIG. 5 is a model diagram showing a state of the resin 40 and the glass fiber 41 in a radial cross section of the piston 2 in the vicinity, and FIG. 5 shows a state of the resin 40 and the glass fiber 41 in an axial cross section of the piston 2 near the small hole 8 of the piston 2. a model diagram showing a, FIG. 6 is a model diagram showing a state of the resin 40 and glass fibers 41 in the axial section of the piston 2 in the vicinity of the small hole 9 of the piston 2, Fig. 7 adopts synthetic resin piston 2 Vehicle It is a cross-sectional view of the brake tandem master cylinder 10 to be needed.
[0016]
As shown in Figures 1-3, the molding die 1 for molding of synthetic resin piston 2 is composed of a upper mold 1a, a lower mold 1b, the side mold 1c, synthetic resin piston on the extension of the second shaft has an injection hole 1d, the rod-shaped projections 1e for forming small holes 8, 9 perpendicular to the axis of the piston 2 in the upper mold 1a, 1f flange portion 4, 6 Are provided near the molding cells 1g and 1h. In molding the piston 2 made of synthetic resin, resin (6-6 nylon mixed with glass fiber) is injected from the resin injection hole 1d. The injected resin flows uniformly in the axial direction of the piston 2 to form the front part 3 and the front side flange part 4, and the direction in which the resin flows on the rod-shaped protrusion part 1 e for forming the small hole 8 is the piston. It is uniformly dispersed in the second radial direction and flows into the portion 1g for molding the front side flange portion 4 of the molding die 1. Furthermore, the resin dispersed and flowing into the portion 1g of the molding die 1 where the front side flange portion 4 is molded gradually flows out in the axial direction of the piston 2 and merges with the subsequent resin flow flowing in the radial direction of the piston 2. resin around the rod-like protrusions 1e by is to be agitated.
[0017]
Resin that has passed through the rod-like projections 1e are flow out uniformly in the axial direction of the piston 2 in order to shape the intermediate portion 5, radially against the rod-like protrusions 1f direction of flow of the resin of the piston 2 for forming the small hole 9 And flows into the portion 1h where the rear flange 6 of the molding die 1 is molded. Further, the resin dispersed and flowing into the portion 1h where the rear flange portion 6 of the molding die 1 is molded flows out gradually in the axial direction of the piston 2, and merges with the subsequent resin flow flowing in the radial direction of the piston 2. resin around the rod-like protrusions 1f by is to be agitated.
[0018]
When the resin and the glass fiber are cooled and solidified in the molding die 1, the front portion 3 of the length L1 portion, the front flange portion 4 of the length L2 portion, and the middle portion 5 which is the thick portion of the length L3 portion are formed. It is composed of a rear flange portion 6 having a length L4 portion and a rear portion 7 having a length L5 portion. The diameters of the front flange portion 4 and the rear flange portion 6 are substantially equal to the diameter of a cylinder hole 11a to be described later. 5 is smaller in diameter than the diameter of the front side flange portion 4 and the rear side flange portion 6, through the shaft of synthetic resin piston 2 in the radial direction of the synthetic resin piston 2 in the rear vicinity of the front side flange portion 4 small and holes 8, the rear side flange portion 6 and the small hole 9 is made of synthetic resin piston provided for in the radial direction of the synthetic resin piston 2 near the front penetrates through the axis of the synthetic resin piston 2 that penetrates Te 2 will be molded.
[0019]
As shown in FIGS. 4-6, the resin 40 and glass fibers 41 in the molded synthetic resin piston 2, the front side flange portion 4 or the rear side flange portion 6, therefore, in the vicinity of the small holes 8, 9 of the piston 2 In the radial cross section, the resin 40 and the glass fibers 41, which are uniformly dispersed and solidified radially and solidify in the axial cross section of the piston 2 in the vicinity of the small holes 8 and 9, solidify in the axial direction of the piston 2 and the diameter of the piston 2 will be resin 40 and glass fibers 41 which hardens facing direction are present, in particular resin 40 and glass fibers 41 which hardens oriented in the radial direction of the piston 2 is increased as compared with the conventional synthetic resin piston.
[0020]
Next, an embodiment in the case of adopting the synthetic resin piston 2 in the brake tandem master cylinder 10 for a vehicle with reference to FIG. 7, the cylinder body 11 is formed with a hollow cylindrical cylinder hole 11a, and the left end in FIG. 7 is closed and the right end is open. A pair of left and right reservoir connecting portions 12 and 13 connected to an oil reservoir (not shown) are formed on the outer periphery of the cylinder main body 11, and the reservoir connecting portions 12 and 13 and the cylinder main body 11 are formed on the peripheral wall of the cylinder main body 11. Supply ports 14a, 14b, 14c, and 14d are formed to communicate with the inside of the.
[0021]
The opening of the cylinder bore 11a metallic piston 15, the central portion is made of synthetic resin piston 2 is inserted for reciprocal sliding respectively. The cylinder bore 11a, together with the second pressure chamber 17 is partitioned by the two pistons 2, 15, the first pressure chamber 16 is defined by a bottom surface of the synthetic resin piston 2 and the cylinder bore 11a.
Further, in order to maintain the first and second pressure chambers 16 and 17 in a liquid-tight manner, cup materials 18, 19, 20, and 21 as sealing materials are provided. and is supported by the rear side flange portion 6 is fitted into the fitting groove of the front portion 3 and the rear portion 7 of the synthetic resin piston 2, the cup member 20, 21 is a metal piston 15
Is fitted.
[0022]
Further, between the cylinder bore 11a and the front side flange portion 4 and the rear side flange portion 6 of the synthetic resin piston 2, i.e., in the outer peripheral surface of the intermediate portion 5, defines a first brake Ekikyo feeding chamber 22 The second brake fluid supply chamber 23 is defined by the cylinder hole 11a and the outer peripheral surface of the metal piston 15.
[0023]
Between the bottom surface of the cylinder hole 11a and the front portion 3 of the synthetic resin piston 2 springs 24 is interposed urges the synthetic resin piston 2 always 7 rightward. Spring 26 between the piston retainer 25 attached to the rear portion 7 and the metallic piston 15 of synthetic resin piston 2 is interposed urges the metal piston 15 always 7 rightward.
[0024]
The stopper member 27 is screwed to the cylinder body 11 and is held at the inoperative position by locking the front flange 4 of the piston 2.
[0025]
When a pressing force is applied to the metal piston 15 in the state of FIG. 7 (non-operating state), the metal piston 15 is moved leftward in FIG. The supplied cup material 20 blocks the supply port 14c, and the pressure of the brake fluid in the second pressure chamber 17 is increased. When the synthetic resin piston 2 by boosting the brake fluid in the second pressure chamber 17 is moved to the left in FIG. 7, the cup member 18 that is mounted in the synthetic resin piston 2 by blocking the supply port 14a The pressure of the brake fluid in the first pressure chamber 16 is increased. The pressure of the brake fluid in both pressure chambers 16 and 17 causes the brake fluid to be pumped to the wheel brakes via an outlet port (not shown).
[0026]
When the pressing force on the metal piston 15 is released, the pistons 2 and 15 are returned to the right in FIG. 7 by the urging forces of the springs 24 and 26. That is, as the pistons 2 and 15 move back, the cup material 18 opens the supply port 14a to connect the first pressure chamber 16 to the first brake fluid supply chamber 22, and the cup material 20 connects the supply port 14c. When released, the second pressure chamber 17 communicates with the second brake fluid supply chamber 23, and the brake fluid pressure is reduced.
[0027]
As described above, according to the method of molding a synthetic resin piston 2 of the present embodiment, at the time of molding of the synthetic resin piston 2, the rod-shaped projections 1e of the molding die, 1f and the front side flange portion 4, random shaped portion 1g of the rear side flange portion 6, in the vicinity of 1h, can be dispersed flow of the resin in the radial direction of the synthetic resin piston 2, also the flow of the resin by stirring the direction of the flow of resin Therefore, when the resin cools and hardens, the shrinkage of the resin in the radial direction of the piston 2 in the flange portions 4 and 6 and the vicinity thereof where dimensional accuracy is particularly required is suppressed, and The contraction of the piston 2 in the axial direction is also suppressed, and it is possible to ensure dimensional accuracy.
[0028]
Further, the provision of the small holes 8 and 9 makes it possible to reduce the thickness of the thick portion, ie, the intermediate portion 5 and thus the vicinity of the flange portions 4 and 6, thereby suppressing the occurrence of voids and cracks.
[0029]
Thus, in particular, to ensure dimensional accuracy in both flanges fraction 4, 6 and its vicinity dimensional accuracy is required by preventing shrinkage of the resin, furthermore, to provide a synthetic resin piston 2 to prevent the occurrence of voids and cracks Is possible.
[0030]
In the present embodiment, the molding die 1 is composed of the upper molding die 1a, the lower molding die 1b, and the side molding die 1c, but needless to say, the invention is not particularly limited to this.
[0031]
Further, in the present embodiment it has been molded synthetic resin piston 2 for Lockheed type master cylinder, by molding a synthetic resin piston for port-less master cylinder in the molding process of synthetic resin piston of the present invention Has the same effect.
Further, in this embodiment, by forming the front portion 3 and the front side flange portion 4 and the intermediate portion 5 and the rear side flange portion 6 and the rear portion 7 for synthetic resin piston 2 consists of a thick portion However, it goes without saying that the present invention is not particularly limited to this shape.
[0032]
Further, in the present embodiment, the bar-shaped protrusions 1e and 1f are arranged in parallel, but the present invention is not particularly limited to this. For example, the bar-shaped protrusions 1e and 1f may in even in the molding process of synthetic resin piston orthogonally and the present invention, the same effect can be obtained. Furthermore, projections of vertical rod-like rod-like protrusions 1e is, or, even in the method of molding a synthetic resin piston of the present invention the projections of the vertical rod-like rod-like protrusions 1f is provided, the same effects can get.
[0033]
As described above, the present invention has been described based on the above-described embodiment. However, the present invention is not limited to the above-described embodiment, but includes various embodiments according to the principle of the present invention.
[0034]
【The invention's effect】
As described above, according to the invention of claim 1, at the time of molding of the synthetic resin piston, in the vicinity of the rod-like projections of the molding die, distributing the flow of the resin in the radial direction of the synthetic resin piston In addition, since the direction of the resin flow can be randomized by stirring the resin flow, the resin shrinks in the radial direction of the piston in the vicinity of the rod-shaped protrusion in the process of cooling and solidifying the resin. Is suppressed, and contraction of the piston in the axial direction is also suppressed, so that dimensional accuracy can be ensured.
[0035]
Furthermore, since the synthetic resin piston hole is provided which extends in the radial direction of the piston passing through the axis of the piston is formed, it is possible to thin the piston by the holes provided, voids , Cracks and the like can be suppressed.
[0036]
Therefore, to ensure dimensional accuracy by preventing shrinkage of the resin at a point such as especially required dimensional accuracy, further, it is made possible to provide a synthetic resin-made piston to prevent the occurrence of voids and cracks.
[0037]
According to the second aspect of the invention, in addition to the effect of the invention of claim 1, at the time of molding of the synthetic resin piston, the rod-shaped projections of the molding die, thus, in the vicinity of the portion for molding the flange portion, the flow of the resin can be dispersed in the radial direction of the synthetic resin piston, also the flow of the resin by stirring the fact that the direction of the flow of resin can be random, in the course of solidification in cold resins, rod-like Since the resin shrinks in the radial direction of the piston in the vicinity of the protrusion and thus in the vicinity of the portion where the flange is formed, shrinkage of the piston in the axial direction is also suppressed, so that dimensional accuracy is ensured. It is possible.
[0038]
Furthermore, since the synthetic resin piston hole is provided in the vicinity of the flange portion passing through the axis of the piston extending in a radial direction of the piston is formed, to be thinned piston by holes provided As a result, it is possible to suppress the occurrence of voids, cracks, and the like.
[0039]
Therefore, allowing the particular securing dimensional accuracy by preventing shrinkage of the resin in the flange portion and its vicinity, such as dimensional accuracy is required, further, to provide a synthetic resin-made piston to prevent the occurrence of voids and cracks And
[0040]
According to the invention of claim 3, in addition to the effect of the invention of claim 2, molded during the molding of the synthetic resin piston, each of the rod-like projections of the molding die, thus, the front and rear side flange portion in the vicinity of the part, it can be dispersed resin flow in the radial direction of the synthetic resin piston, also the flow of the resin by stirring the fact that the direction of the flow of resin can be random, cold resin In the process of hardening, the contraction of the resin in the radial direction of the piston in the vicinity of the respective bar-shaped protrusions and, in turn, in the vicinity of the portions where the front and rear flanges are formed is suppressed, and the axial contraction of the piston is also suppressed. Therefore, it is possible to ensure dimensional accuracy.
[0041]
Furthermore, since a synthetic resin piston is formed in which a hole extending in the radial direction of the piston and passing through the axis of the piston is provided near the front and rear flanges , the piston is formed by providing the hole. Can be made thinner, and the generation of voids, cracks, and the like can be suppressed.
[0042]
Therefore, the synthetic resin used in the master cylinder for a vehicle ensures the dimensional accuracy by preventing the resin from shrinking at and around the flange portion where the dimensional accuracy is particularly required, and further prevents the occurrence of voids and cracks. It is possible to provide a piston made of .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a molding die 1 according to an embodiment.
2 is a cross-sectional view of the synthetic resin piston 2 embodiment.
FIG. 3 is a top view of FIG. 2;
FIG. 4 is a model diagram showing a state of resin and glass fibers in a radial section of piston 2 near small holes 8 and 9 in FIG.
FIG. 5 is a model diagram showing a state of resin and glass fibers in an axial cross section of the piston 2 near a small hole 8 in FIG. 3;
6 is a model diagram showing a state of resin and glass fibers in an axial cross section of the piston 2 near a small hole 9 in FIG.
7 is a cross-sectional view of a brake master cylinder for a vehicle employing a synthetic resin piston of FIG.
FIG. 8 is a model diagram showing a state of resin and glass fibers in an axial section of a piston 100 near a flange portion 101 according to a conventional technique.
[Explanation of symbols]
1 molding die 1d injection holes 1e, 1f rod-like protrusions 1 g, 1h flanging portion 2 made of synthetic resin piston 4 the front side flange portion 6 rear side flange portion 11 cylinder body 11a cylinder bore

Claims (3)

Filling a resin from the resin injection hole into a molding die having a resin injection hole provided on an extension of the axis of the piston and having a rod-shaped protrusion perpendicular to the axis. The method of molding a piston made of synthetic resin according to the present invention. Said piston, said piston has a substantially equal flange portion to the diameter of the cylinder bore of the cylinder body that is inserted slidably, protrusion of the rod-shaped, forming the flange portion of the molding die method of molding a synthetic resin piston according to claim 1 provided in the vicinity of the site of. Said cylinder body is a cylinder body of the vehicle master cylinder, said piston forming method of the synthetic resin piston according to claim 2 having the flange portion at two positions on the front side and rear side.

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