JPH102416A - Fluid pressure cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure cylinder compact and low in cost so as to reduce the number of part items and assembly work manday. SOLUTION: A piston 1 of a fluid pressure cylinder consisting of a cylinder tube, the piston 1 disposed in an axially movable state in the cylinder tube, and a piston rod 2 rigidly fixed to the piston 1, is formed of synthetic resin, and the piston rod 2 is insert-formed at the piston 1 so as to form the piston 1 and piston rod 2 integrally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cylinder and, more particularly, to a technology effective when applied to a piston of a hydraulic cylinder.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 12 and 13, a piston of a fluid pressure cylinder has a piston 12 attached to an end of a piston rod 11 by caulking 13, or a male screw 14 attached to an end of the piston rod 11. In general, the piston 12 is formed and fixed in the cylinder tube 16 by fixing the piston 12 with the nut 15.

[0003]

However, in the case of a hydraulic cylinder having a piston having such a structure, a crimping operation, an assembling operation, a nut tightening operation, and the like are required, and the manufacturing cost increases accordingly. There was a problem. Also, the number of parts such as washers, nuts, adhesives, etc. has increased, which has contributed to an increase in cost. Further, in the case of a type in which a magnet is attached to a piston, a space for the magnet is required, and in addition to the above-mentioned problems, there is a problem that it is difficult to reduce the size of the product.

An object of the present invention is to provide a small-sized and low-cost hydraulic cylinder in which the number of parts and the number of assembling operations are reduced.

[0005] The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0006]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, a fluid pressure cylinder according to the present invention is a fluid having a cylinder tube, a piston disposed axially movably in the cylinder tube, and a piston rod fixed to the piston. A pressure cylinder, wherein a piston is formed of a synthetic resin, and a piston rod is insert-molded in the piston to integrally form the piston and the piston rod.

In this case, a magnet may be further inserted into the piston, and the piston, the piston rod and the magnet may be integrally formed, or the piston may be formed of a resin magnet.

On the other hand, in the fluid pressure cylinder of the present invention, the piston of the fluid pressure cylinder having a cylinder tube and a piston disposed movably in the axial direction in the cylinder tube is formed of synthetic resin. Alternatively, a magnet may be insert-molded into the piston to integrally form the piston and the magnet, or the piston itself may be formed from a resin magnet.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is an enlarged sectional view of a piston portion of a fluid pressure cylinder according to Embodiment 1 of the present invention. In the first embodiment, the piston 1 and the piston rod 2 are integrally formed by insert molding. The piston 1 is disposed in a cylinder tube (not shown) so as to be movable in the axial direction and constitutes a fluid pressure cylinder, similarly to the conventional fluid pressure cylinder shown in FIGS. Known configurations can be appropriately applied to portions other than the piston portion described above, and details thereof are omitted.

Here, in the first embodiment, the piston 1 is formed of a synthetic resin such as polyacetal or nylon. In the center, as shown in FIG. 1, a metal piston rod 2 such as SUS or S45C is used.
Are mounted integrally with the piston 1. In this case, the piston rod 2 is formed integrally with the piston 1 by insert molding when the piston 1 is molded. That is, a mold is used in which the piston rod 2 is inserted into the mold, the mold is closed, and a synthetic resin is injected into the mold to perform injection molding, using a mold vertically divided using the line AA in FIG. 1 as a parting line. As a result, a part in which the piston 1 and the piston rod 2 are integrated is formed.

The piston rod 2 is provided with a stepped retaining portion 2a.
Is prevented from dropping from the piston 1. Also,
A packing groove 1a is provided on the circumferential surface side of the piston 1, and a piston packing 3 is fitted therein.

On the other hand, the form of the piston rod 2 can be variously modified, and modified examples are shown in FIGS. 2 (a) to 2 (c). Here, FIG. 2A shows a mode in which the fluid pressure cylinder is a so-called double rod type, and a piston rod 2 extends on both sides of a piston 1. In this case, both sides of the retaining portion 2a are formed in a tapered shape. Next, FIG. 2 (b) shows that the retaining portion 2a is formed in a knurled shape in a screw shape.
Is fixed so as to slightly protrude from the end face of the rim. Further, FIG. 2 (c) shows a state where the piston rod 2 is insert-molded in a state where the piston rod 2 is included in the piston 1.

In some cases, a magnet is attached to the piston 1 in order to detect the position of the piston of the hydraulic cylinder. FIGS. 3A and 3B show modified examples in which the magnet 4 is attached. In this case, FIG.
As shown in (1), a boss 1b is formed on the piston 1, and the magnet 4 is attached to the piston 1 by press-fitting a support 5 into which a ring-shaped magnet 4 is inserted. Also, as shown in FIG. 3 (b), after the magnet 4 is attached, bumpers 6 can be provided on both sides of the piston 1 for absorbing shock and preventing sound generation. In addition,
3A and 3B, a small-diameter portion is provided on the piston rod 2 as a retaining portion 2a, and the piston 1 is provided there.
Is formed to prevent the piston rod 2 from coming off.

Thus, according to the present invention, the piston 1
Since the piston rod 2 and the piston rod 2 are integrally formed, it is possible to omit a caulking operation for attaching the both, a component such as a washer, a nut, an adhesive, and an assembling operation thereof.
Therefore, the number of parts and the number of assembly steps can be reduced, and the cost of the product can be reduced.

Embodiment 2 Next, a fluid pressure cylinder according to Embodiment 2 of the present invention will be described. FIG.
(A), (b) is sectional drawing to which the piston part was expanded.

In the second embodiment, the magnet 4 is also formed integrally with the piston 1 as shown in FIG. That is, when the piston 1 is formed, the ring-shaped magnet 4 is also insert-molded into the piston 1 together with the piston rod 2. In this case, as shown in FIG. 4B, after the piston 1 is formed, bumpers 6 are formed on both sides thereof.
Can also be provided.

Here, in FIGS. 4 (a) and 4 (b), a ring-shaped magnet is used for the magnet 4, but instead a detent hole as shown in FIGS. 5 (a) and 6 (a). The magnet 4 having the 4a and the detent groove 4b may be used. FIG. 5 shows a magnet molded using such a magnet 4.
(B) and FIG. 6 (b). In this case, when the magnet 4 is insert-molded into the piston 1, the synthetic resin wraps around the detent hole 4a and the detent groove 4b, and the magnet 4 is integrally molded with the piston 1 in a state where the movement in the circumferential direction is restricted. .

FIG. 7 shows another modification. In FIG. 7, the magnet 4 is wrapped in a synthetic resin. In this case, since the magnet 4 is covered with the synthetic resin, the distance between the magnet 4 and a sensor (not shown) increases. Therefore, it is necessary to make the covering portion as thin as possible or to use a magnet having a stronger magnetic force.

As described above, according to the structure of the second embodiment, since the magnet 4 is integrated with the piston 1 in addition to the piston rod 2, FIG.
Parts such as the support 5 shown in (b) become unnecessary, and the number of parts can be further reduced, and the number of assembly steps can be reduced.

Although the piston rod 1 and both the piston rod 2 and the magnet 4 are insert-molded so far, the piston rod 2 is separately provided and only the magnet 4 is insert-molded into the piston 1. Of course, it is also possible. FIGS. 8A and 8B are diagrams showing such a development example of the second embodiment.
8A corresponds to FIG. 4A, and FIG. 8B corresponds to FIG. These are a piston 1 having a magnet 4
And each is attached to the piston rod 2 by a nut or the like. For this reason, the number of parts and man-hours cannot be reduced in terms of attachment to the piston rod 2, but since the magnet 4 is already integrated with the piston 1, the man-hour related to the magnet is reduced.

Embodiment 3 Further, a fluid pressure cylinder according to Embodiment 3 of the present invention will be described. FIG.
(A), (b) is sectional drawing to which the piston part was expanded.

In the third embodiment, the piston 1 itself is formed by a plastic magnet (resin magnet). As shown in FIGS. 9A and 9B, the piston rod 2 is formed by insert molding. I have. That is, the piston 1 is formed of a so-called plastic magnet using a synthetic resin as a binder, and is injection-molded by, for example, mixing ferrite and a synthetic resin. Then, at the time of molding, the piston rod 2 is insert-molded, and the piston 1 and the piston rod 2 are integrally formed. In this case, the piston 1 is appropriately magnetized after molding and used for use. Therefore, in the case of a fluid pressure cylinder that does not require a magnet, it may be used without being magnetized, and the application can be properly used depending on the presence or absence of magnetization.

On the other hand, in order to improve the magnetic force by forming a magnetic path, a metal yoke 7 may be simultaneously insert-molded as shown in FIG. In this case, a magnetic field is generated on the circumferential surface side of the piston 1 by the yoke 7, which is more convenient for detecting the piston position. In addition, the yoke 7 allows the piston 1
Is also reinforced. The yoke 7 is provided with a detent hole 7a, into which the synthetic resin wraps, so that the yoke 7 is integrally formed with the piston 1 in a state in which movement in the circumferential direction is restricted.

As described above, by forming the piston 1 with a plastic magnet, the magnet itself can be omitted, and not only the number of parts and the number of assembly steps but also the space for the magnet can be reduced. Therefore, the length of the piston portion can be reduced, and the product can be made thinner and smaller.

Incidentally, also in the third embodiment, it is of course possible to form only the piston 1 by a plastic magnet, separately from the piston rod 2.
11 (a) to 11 (c) are diagrams showing such a development example of the third embodiment. FIG. 11 (a) is shown in FIG. 9 (a), and FIG. 11 (b) is shown in FIG. 9 (b). ), And FIG.
It corresponds to. These are formed as a single piece of a piston 1 made of a plastic magnet, and after being appropriately magnetized, attached to the piston rod 2 with a nut or the like. Also in this case, since the piston 1 itself is a magnet, the number of steps related to the magnet can be reduced in the same manner as described above.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment and can be variously modified without departing from the gist of the invention. Needless to say,

For example, the modifications shown in the embodiments are not limited to those described above, and it is needless to say that various embodiments such as those obtained by appropriately combining these are conceivable. Further, in each of the embodiments, the piston rod is assumed to be made of metal. However, the piston rod may be made of synthetic resin depending on the degree and size of the load and the application.

In the above description, the case where the invention made by the inventor is mainly applied to a fluid pressure cylinder having a piston rod, which is a field of application, has been described. However, the present invention is not limited to this. For example, FIG.
The pistons shown in FIGS. 11A and 11B and FIGS. 11A to 11C can be applied to a so-called rodless cylinder.

[0031]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

(1) Since the piston rod is insert-molded into the piston to integrate them, it is possible to omit a caulking operation for attaching the piston rod, a component such as a washer, a nut, an adhesive, and an assembling operation thereof. Therefore, the number of parts and the number of assembly steps can be reduced, and the cost of the product can be reduced.

(2) Since the piston rod and the magnet are insert-molded into the piston and integrated with each other, the number of parts and the number of assembling steps for the support member and the like can be further reduced, and the cost can be further reduced. . In addition, only the magnet can be insert-molded into the piston to integrate them, and in that case, the man-hour for mounting the magnet and the number of support members can be reduced.

(3) By forming the piston with a plastic magnet, the magnet can be omitted. Therefore, not only the number of parts and the number of assembling steps but also the space for the magnet can be reduced, so that the product can be reduced in thickness and reduced in size in addition to the cost reduction of the product. In addition, since the magnetization is performed after the molding, there is also an effect that the piston can be used for general purpose regardless of the necessity of the magnet depending on the presence or absence of the magnetization.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a piston portion of a fluid pressure cylinder according to a first embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views illustrating a modification of FIG. 1; FIG. 2A is a modification in which a piston rod is a double rod type; FIG. 2B is a modification in which a retaining portion is formed in a screw shape; Is a modified example in which a piston rod is included.

FIGS. 3A and 3B are cross-sectional views illustrating a modification of FIG. 1, wherein FIG. 3A is a modification in which a magnet is attached, and FIG. 3B is a modification in which a bumper is further attached.

FIG. 4 is an enlarged sectional view of a piston portion of a fluid pressure cylinder according to a second embodiment of the present invention, wherein (a) shows an example using a ring-shaped magnet, and (b) shows a bumper in (a). It is a modified example of attachment.

5A and 5B are diagrams showing a modification of FIG. 4A, wherein FIG. 5A is a plan view of a magnet used in the modification, and FIG. 5B is a sectional view of the modification.

FIG. 6 is a diagram showing another modified example of FIG.
(A) is a plan view of a magnet used in the modification,
(B) is a sectional view of the modification.

FIG. 7 is a cross-sectional view showing still another modified example of FIG.

FIG. 8 is a cross-sectional view showing, as a development example of the second embodiment, only a magnet that is insert-molded, and FIG.
FIG. 4A is a development example corresponding to FIG. 4A, and FIG. 4B is a development example corresponding to FIG.

FIG. 9 is an enlarged cross-sectional view of a piston portion of a fluid pressure cylinder according to a third embodiment of the present invention. FIG. 9A is an example in which a single rod type piston rod is insert-molded, and FIG. This is an example in which a rod-type piston rod is insert-molded.

FIG. 10 is a cross-sectional view showing a modification of FIG.

FIGS. 11A and 11B are cross-sectional views showing a piston formed by a plastic magnet as a development example of the third embodiment, where FIG. 9A is shown in FIG. 9A, and FIG.
(C) is a development example corresponding to FIG.

FIG. 12 is a sectional view showing a piston structure of a conventional hydraulic cylinder.

FIG. 13 is a sectional view showing a piston structure of a conventional hydraulic cylinder.

[Description of Signs] 1 Piston 1a Packing groove 1b Boss part 2 Piston rod 2a Retainer 3 Piston packing 4 Magnet 4a Detent hole 4b Detent groove 5 Support 6 Bumper 7 Yoke 7a Detent hole 11 Piston rod 12 Piston 13 Caulking 14 Male thread 15 Nut 16 Cylinder tube

Claims (5)

[Claims] 1. A fluid pressure cylinder comprising: a cylinder tube; a piston disposed axially movably in the cylinder tube; and a piston rod fixed to the piston. Is made of synthetic resin, and the piston rod is insert-molded to the piston to integrally form the piston and the piston rod. 2. A hydraulic cylinder according to claim 1, wherein a magnet is further insert-molded on said piston, and said piston, said piston rod and said magnet are formed integrally. . 3. The hydraulic cylinder according to claim 1, wherein said piston is formed of a resin magnet. 4. A fluid pressure cylinder comprising: a cylinder tube; and a piston disposed movably in an axial direction in the cylinder tube, wherein the piston is formed of a synthetic resin. A fluid pressure cylinder, wherein a magnet is insert-molded to integrally form the piston and the magnet. 5. A fluid pressure cylinder comprising a cylinder tube and a piston disposed axially movably in the cylinder tube, wherein the piston is formed by a resin magnet. Fluid pressure cylinder.