JPH0681948A - Cylinder device - Google Patents

Abstract

(57) [Abstract] [Purpose] Weight reduction of the piston rod used in the cylinder device. [Constitution] Cylindrical or hollow cylindrical FRP piston rod body 10 formed by continuous continuous fiber pultrusion
And the metal joint members 12 and 14 attached to both ends thereof form a piston rod. The joint member has no thread at the contact portion with the piston rod body. [Effect] Light weight and high strength. It can be manufactured easily and inexpensively.
Metal plating on the outer periphery of the rod body improves wear resistance, scratch resistance, and corrosion resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device used as a hydraulic or pneumatic cylinder for industrial robots, conveyors and the like, and more particularly to a cylinder device which is excellent in wear resistance and has a reduced weight.

[0002]

2. Description of the Related Art In recent years, attempts have been made to reduce the weight in various industrial fields from the viewpoint of energy saving, and the cylinders used as power systems associated with industrial robots and carrier machines are also required to be reduced in weight. .

As one of the means for reducing the weight, it is known to use fiber reinforced plastic (hereinafter abbreviated as FRP) instead of metal. Also in a cylinder device in which a piston slides in a cylinder tube, it is possible to use a filament winding method (hereinafter, abbreviated as FW method) to make the piston rod for driving the piston into FRP. It is proposed in each publication of 2-235728.

Conventional FRs described in these publications
The P-shaped piston rod is a hollow cylindrical body made of a glass fiber unidirectionally drawn material and a FRP layer formed by the FW method around the core material, or a FRP layer formed by the FW method using a mandrel. Consists of.

FIG. 1 shows an example of a cylinder device. Reference numeral 1 is a cylinder tube, both ends of which are covered with covers. Reference numeral 2 is a piston slidably fitted in the tube, and 3 is a piston rod fixed to the piston for driving the piston. The piston rod is inserted into the tube through a through hole provided in one end surface cover of the cylinder tube. The diameter of the piston rod is much smaller than that of a cylinder tube,
It is long and is composed of solid or thick hollow tubes to ensure strength. Therefore, since the piston rod normally occupies about half of the weight of the entire cylinder device, it is important to reduce the weight of the piston rod in order to reduce the weight of the cylinder device.

[0006]

However, despite the small diameter of the piston rod, a strong force is applied to drive the piston, and strength is required. Further, in order to connect to the power source and the piston, it is necessary to form a joint portion by threading at both ends of the piston rod. For the above reasons, in the production of the conventional FRP-made piston rod, the method of winding the fiber at various angles by the FW method and reinforcing the fiber has been adopted as described above. However, in the case of manufacturing by this conventional molding method, in order to make the strength distribution of the material uniform, the number of windings of the fiber was inevitably increased, and the fiber had to be thick. Therefore, it cannot be said that the weight reduction effect by using FRP is sufficient.

Further, as described above, the joint portions are usually provided at both ends of the piston rod.
When both ends of the rod formed by the method are threaded, the strength is not sufficient with FRP alone, and even if threads are formed on both ends by the FW method, the rod itself has a very small diameter It was difficult to obtain a stable strength. Furthermore, the outer peripheral surface of the piston rod is
Since it slides in contact with the through hole of the end cover of the cylinder tube and a part of it is exposed to the outside, in order to ensure long-term use of the cylinder device, the resistance of the outer peripheral surface of the piston rod is It is required to improve wear resistance and scratch resistance.

An object of the present invention is to provide a cylinder device having a piston rod, which has a higher weight reduction effect than the conventional FRP type piston rod, can be used for a long period of time, and can be manufactured inexpensively and easily.

[0009]

DISCLOSURE OF THE INVENTION As a result of studies to achieve the above-mentioned object, the present inventor has noticed that the stress applied to the piston rod may be considered only in the rod direction. FRP by orienting in one direction
When the manufactured piston rod was molded, it was possible to obtain a piston rod that was thinner than the conventional one and had sufficient strength. By making the joints such as screws at both ends of the piston rod made of metal, it is possible to compensate for the insufficient strength of the joints due to the thinning.

Here, the gist of the present invention is a cylinder device comprising a cylinder tube, a piston that slides in the tube, and a piston rod that is connected to the piston and that drives the piston. Is composed of a cylindrical or hollow cylindrical FRP piston rod main body formed by continuous continuous fiber pultrusion, and metal joint members attached to both ends thereof, and the joint member is in contact with the piston rod main body. The cylinder device is characterized by not having a screw thread in the part.

In a preferred mode, metal plating is applied to the outer peripheral surface of the piston rod to suppress wear and damage, which enables long-term use.

[0012]

The structure of the present invention will be described in detail below together with its operation. In the present invention, of the cylinder tube, piston, and piston rod that are the main constituent members of the cylinder device, the piston rod that occupies about half of the total weight of the device is made into FRP. Instead of forming by the FW method of winding, the continuous continuous fiber is formed into a cylindrical or hollow cylindrical shape by pultrusion. By forming the piston rod body by pultrusion, it is possible to obtain a piston rod in which all continuous long fibers are aligned in the rod direction (length direction).

By unidirectionally orienting the fibers in the rod direction, with respect to the strength in the rod direction, the strength required for the piston rod can be secured with a smaller number of fibers as compared with the FW method in which continuous continuous fibers are wound. It is possible to reduce the wall thickness. As described above, the stress applied to the piston rod may be considered only in the rod direction. Therefore, by aligning the fibers in the rod direction, the reinforcing effect can be most effectively exhibited with a small number of fibers.

In the pultrusion molding, a bundle (roving) of continuous continuous fibers is unidirectionally aligned is impregnated with the resin by a conventional method, and the resin is drawn out from a circular or annular die to form a cylindrical or hollow cylindrical shape. Can be carried out by curing. The curing of the resin may be either thermal curing or curing by irradiation with ultraviolet rays or electron beams. The type of continuous long fibers used is not limited, and ceramic fibers such as carbon fibers and alumina fibers, or metal fibers can be used, but glass fibers are usually used.

The resin with which the fibers are impregnated may be any thermosetting resin, and may be selected in consideration of performance and cost. Suitable thermosetting resins include vinyl ester resins, epoxy resins, thermosetting polyester resins, polyimide resins and the like. A curing agent or an accelerator can be added to the resin. If necessary, various additives such as pigments and antioxidants may be added to the resin.

The cylindrical or hollow cylindrical FRP molded body obtained by pultrusion is cut into an appropriate length, if necessary, to form a piston rod body. Since the piston rod is usually connected to the piston at one end and to the power source at the other end, it is necessary to provide joints for the connection at both ends of the piston rod.

In the pultruded body, the fibers are oriented in one direction,
The strength in the radial and shear directions is not high. for that reason,
In the present invention, instead of directly forming a joint portion such as a screw thread on both ends of a piston rod body formed by a pultrusion molding or a hollow cylindrical body, metal joint members are formed on both ends of the body. By mounting the piston rod, the piston and the power source are connected.
By securing the strength of the joint portion by the metal joint member, the piston rod can be formed only by the drawn material without disposing the FW layer around the one-way drawn material as described in JP-A-62-215104. It becomes possible to configure the main body of.

As the material of the metal joint member (metal fitting), it is preferable to use carbon steel, stainless steel, titanium or the like having high strength. In order to enhance the weight reduction effect, a metal fitting made of a light metal such as titanium is advantageous. When the piston rod body is a cylindrical body, holes for inserting metal fittings are provided at both ends of the body with a drill or the like. The inserted metal fitting is fixed to the piston rod body with an adhesive. By using the metal joint member, the joint strength is increased and the reliability of the cylinder device is improved as compared with the conventional case where the FRP layer is threaded.

The shape of the metal fittings attached to both ends of the piston rod varies depending on the connection partner, and is not particularly limited, but the portion contacting the piston rod body (that is, the metal fitting portion inserted into the inside of the piston rod) has a screw thread. Not have. If there is a thread on the part of the metal fitting that is inserted into the piston rod, stress concentrates on the piston rod part that contacts the thread part of the metal fitting, and excessive radial stress is locally applied to that part of the rod. Vertical cracking of the rod is likely to occur.

An example of the shape of the metal fitting suitable for mounting inside the piston rod body in the present invention is shown in FIGS. 2 and 3.
Shown in. FIG. 5 shows an example of the piston rod of the present invention in which the joint members (metal fittings) 12 and 14 having the shape shown in FIG. 3 are attached to both ends of the cylindrical piston rod body 10. The metal fitting shown in FIG. 4 is a metal fitting of a type that is not used in the present invention and has a screw thread in a portion to be inserted into the piston rod body.

In order to prevent abrasion of the outer peripheral surface of the piston rod body (due to contact with the through hole of the tube cover) due to long-term use, metal plating may be applied to the outer peripheral surface.
This wear prevention can be achieved by disposing a resin layer on the outer circumference of the piston rod main body, but the outer peripheral surface of the piston rod is the part exposed to the outside and scratch resistance is also required, so it has excellent scratch resistance. It is advantageous to apply a metal plating. This significantly extends the service life of the piston rod. The piston rod main body can be plated by a method such as metallizing or galvanizing, and a chromium-based metal that is rich in wear resistance and corrosion resistance is suitable as the plated metal. Two or more plating layers can be provided, and the thickness of the plating layers is preferably in the range of about 2 to 200 μm as a whole.

In the piston rod used in the present invention, the piston rod body can be efficiently molded by the pultrusion molding method instead of the FW method, which requires complicated molding operations.
Compared with the conventional FRP piston rod by the FW method,
Not only is it possible to reduce the weight and thickness, but the manufacturing process is simple and efficient, and the piston rod can be manufactured at a lower cost.

In the cylinder device of the present invention, aluminum die casting or the like can be used as the material of the piston. The material of the cylinder tube is also not particularly limited,
In order to further satisfy the purpose of reducing the weight, the cylinder tube is preferably made of FRP.

[0024]

Example 1 Epoxy resin (Dow Chemical Japan, DER 331J) was used as a matrix resin, and 80% by weight of a curing agent (HN-2200, manufactured by Hitachi Chemical Co., Ltd.) with respect to the main agent and an accelerator (Shikoku Chemical) 1% by weight of Cuzazole 2E4MZ) manufactured by Kogyo Co., Ltd. was blended. Using glass roving (E-glass roving R2220 TMF08 made by Asahi Fiber Glass) as the reinforcing fiber, impregnating it with the above-mentioned compounded resin and pulling it in one direction, and then heating the drawn material at 130 ° C for 2 hours in a heating furnace. Then, the resin was cured to obtain a cylindrical molded body having a diameter of 14 mm and a length of 350 mm. No winding layer was formed on the outer periphery by the FW method.

Two cylindrical rod bodies thus obtained were prepared, and Ni plating 0.2 μm, copper plating 10 μm, and Cr plating 30 μm were sequentially formed on the outer peripheral surface from the bottom by the electrogalvanizing method to provide wear resistance. Let Drill a cylindrical hole with a diameter of 6 mm and a depth of 29 mm at both ends of each rod body, insert the metal joint member made of stainless steel (SS41) in the shape shown in Figs. Agent (Ciba Geigy, Araldide Rapid Type)
And the piston rod of the present invention was manufactured.
The obtained piston rods were all about 10% lighter in weight than the conventional products manufactured by the FW method and having the same length.

The results of the tensile test of each of the obtained piston rods at a tensile speed of 1 mm / min are shown in Table 1 below. Maximum load is the value of the maximum load that is expected during use of the piston rod. Regarding the piston rod equipped with both the metal fittings shown in Fig. 2 and Fig. 3, the maximum load
It was able to withstand 10 times the load and was good in terms of reliability of plastic products.

[0027]

[Table 1]

Example 2 Using the same material and molding method as in Example 1, a pultruded body having a hollow cylindrical shape (outer diameter 16 mm, wall thickness 4 mm) was obtained. No winding layer was formed on the outer periphery by the FW method. The outer peripheral surfaces of the two hollow cylindrical rod bodies were plated in the same manner as in Example 1 from the bottom with Ni plating 0.2 μm and copper plating 10 μm.
A Cr plating of 20 μm was formed to provide abrasion resistance. Insert metal joint members made of stainless steel (SS41) with the shape shown in Fig. 2 and Fig. 3 into both ends of each rod body, and bond them with epoxy adhesive (Ciba Geigy, Araldide Rapid Type) Invented piston rod of the invention. The obtained piston rods were all about 15% lighter than the conventional products of the same length manufactured by the FW method.

The following Table 2 shows the results of the tensile test of each of the obtained piston rods at a tensile speed of 1 mm / min. The piston rod equipped with any of the metal fittings shown in FIGS. 2 and 3 was able to withstand a load of about 10 times the maximum load even when the piston rod had a hollow shape.

[0030]

[Table 2]

Comparative Example 1 The same cylindrical piston rod body was manufactured by using the same material and molding method as in Example 1, and the holes formed at both ends of the piston rod body were as shown in FIG.
The metal joint member made of stainless steel (SS41) screwed as shown in was inserted and bonded with the same adhesive. Similarly, when the adhesive strength was measured, stress was concentrated on the screw thread portion, so that vertical cracking occurred at a load in the vicinity of three times the assumed maximum load, and the reliability was poor.

[0032]

Although the piston rod of the cylinder device of the present invention is lightweight, it has high strength in the rod direction, which is the direction in which force is applied to the piston rod, and its performance is sufficient. Further, the piston rod of the present invention can be manufactured simply and efficiently at low cost. Furthermore, by applying metal plating to the outer peripheral surface of the piston rod, wear resistance, scratch resistance, and corrosion resistance are improved, and it is expected that the range of usage environment will be expanded.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional explanatory view showing an example of a cylinder device.

FIG. 2 is an explanatory view showing an example of the shape of a metal joint member attached to both ends of a piston rod according to the present invention.

FIG. 3 is an explanatory view showing another example of the shape of the metal joint member suitable for use in the present invention.

FIG. 4 is an explanatory view showing another example of the shape of a metal joint member for comparison.

FIG. 5 is an explanatory view showing a cross section of both ends of the piston rod of the present invention.

[Explanation of symbols]

1: Cylinder tube 2: Piston 3: Piston rod 10: Piston rod body 12, 14: Joint member

Claims (2)

[Claims] 1. A cylinder device comprising a cylinder tube, a piston that slides in the tube, and a piston rod that is connected to the piston and that drives the piston, wherein the piston rod is a continuous continuous fiber withdrawal unit. It is composed of a cylindrical or hollow cylindrical FRP piston rod body formed by molding, and metal joint members attached to both ends thereof, and the joint member does not have a screw thread at a contact portion with the piston rod body. A cylinder device characterized in that 2. The cylinder device according to claim 1, wherein the outer peripheral surface of the piston rod is plated with metal.