JPH0641765B2 - Elastic contractor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to improvement of fatigue life and performance efficiency of an elastic contraction body.

(Prior Art) An elastic contractor is composed of an inner cylinder as a tubular member made of rubber or a rubber-like elastic body, and a braided structure covering the outer circumference of the inner cylinder. When both ends are closed and pressure is applied to the internal space. The braided structure has a structure in which it contracts in the axial direction as it expands in the radial direction due to pantograph movement, and the member or device connected to the actuator by the contracting force generated at this time (for example, a robot joint). It is a mechanism to move. In this case, the braided structure and the inner cylinder are not connected to each other in order to prevent the resistance against the diameter change of the inner cylinder from being generated.

As such an elastic contractor, Japanese Patent Application No. 58-7140
4 and Japanese Patent Application No. 58-160544.

(Problems to be Solved by the Invention) By the way, the elastic contraction body generally has performance degradation, that is, fatigue life reduction and performance efficiency reduction with respect to the theoretical formula, and the difference increases as the amount of deformation increases. One of the causes of the decrease in performance efficiency is the elastic resistance of the inner cylinder made of rubber or rubber-like elastic material. To reduce this, there is no choice but to lower the elastic resistance of the inner cylinder, but there is a limit to this. .

Friction loss is another cause of reduced performance efficiency and reduced fatigue life. Usually, a braided structure of a multi-filament fuel cord having irregularities on the surface is used for the reinforcing layer, but in such a reinforcing layer, the friction between the cords is large at the time of deformation, which becomes the deformation resistance of the reinforcing layer,
Further, rubbing between the inner cylinder and the reinforcing layer at the time of deformation also causes driving loss, and wear and tear resulting from this also lead to a decrease in fatigue life.

As a means for reducing this friction loss, it has been proposed to make the cord constituting the reinforcing layer a smooth monofilament to reduce the friction between the cords and the friction between the cord and the inner cylinder. Such a smooth monofilament braided structure is 20 times better than a twisted cord multifilament braided structure.
The performance efficiency can be improved by about 60%, which leads to a significant performance improvement. On the other hand, however, the frictional resistance between the cords is small, so the knitting of the reinforcing layer is likely to occur during repeated deformation, and if the knitting occurs, the bulge diameter becomes uneven, leading to a large decrease in performance. There was a problem that I could not do it.

(Means for Solving Problems) An object of the present invention is to solve the problems in such a conventional elastic contraction body and to obtain an elastic contraction body capable of reducing drive loss without causing breakage of the reinforcing layer. is there. To achieve this object, the elastic contraction body of the present invention comprises an inner cylinder made of rubber or a rubber-like elastic body, and a first reinforcing layer made of a smooth monofilament cord braided structure surrounding the outer circumference of the inner cylinder. A second reinforcing layer composed of a braided structure of twisted cords of multifilament having irregularities on the surface surrounding the outer periphery of the first reinforcing layer, end closing members for closing both ends of these, and a fluid pressure inside the inner cylinder. And a fluid pressure supply port for supplying.

(Operation) According to this configuration, since the first reinforcing layer that is in contact with the inner cylinder is a smooth braided structure of monofilament cord, friction between the first reinforcing layer and the inner cylinder during deformation is generated. The first reinforcing layer is surrounded by the second reinforcing layer of the multi-filament twisted cord braided structure having low resistance and frictional resistance between the cords of the first reinforcing layer and having irregularities on the surface. Knitting is prevented.

(Example) Hereinafter, the elastic contraction body of the present invention will be described in detail with reference to the drawings.

1 and 2 are views showing an embodiment of the elastic contraction body of the present invention. In FIGS. 1 and 2, reference numeral 1 denotes an inner cylinder made of rubber or a rubber-like elastic body, and the outer circumference of the inner cylinder 1 is covered with a first reinforcing layer 2a made of a smooth braided monofilament cord structure. The outer periphery of the first reinforcing layer 2a is further covered with a second reinforcing layer 2b composed of a braided structure of twisted cords of multifilament having irregularities on the surface. Both ends of these are closed by end closing members 3, and both ends of the inner cylinder 1, the first reinforcing layer 2a, and the second reinforcing layer 2b are fixed to the end closing members 3 by caulking caps 4. The end closing member 3 is the inner cylinder 1
Of the nipple 5 which is tightly fitted to the openings of both ends of the nipple 5 for sealing and bonding, preferably using an adhesive, a flange 6 for positioning, and an eye or clevis end 7 with a connecting pin hole. It is possible to provide a ring-shaped projection 8 for preventing slip-off, which forms a gentle taper toward the tip with a sharp taper in the opposite direction on the outer circumference. One of the end closing members 3 has a connection hole 11 communicating with the inner cavity 10 of the inner cylinder 1 through a hole 9 formed in at least one side in the length direction of the nipple 5.
Then, the fitting 12 having the fluid pressure supply port 12a formed therein is attached thereto.

The caulking cap 4 engages with the flange 6 to cover the outer circumference of the end of the inner cylinder, and is made of a cylindrical metal member having a flare 13 formed at the end, and locally presses the nipple 5 in the radial direction to close the end. The member 3 is sealed and attached to the inner cylinder 1.

Next, the operation of this elastic contractor will be described. When the fluid pressure is supplied from the fluid pressure supply device (not shown) into the internal cavity 10 of the inner cylinder 1 through the fluid pressure supply port 12a, the first reinforcing layer 2a is formed.
The action of the second reinforcing layer 2b brings about a reduction in the axial direction due to the expansion in the radial direction, and by utilizing this, a predetermined member connected to the elastic contraction body is driven. The driving force at the time of this driving is that the first reinforcing layer 2a is made of a smooth monofilament cord braided structure to reduce the friction loss at the time of deformation of the elastic contraction body, and the entire reinforcing layer is twisted cord of the multi-filament. It is larger than that created by. Since the second reinforcing layer 2b is a braided structure of multi-filament twisted cords having irregularities on the surface, it is difficult for the braid to collapse, and the second reinforcing layer 2b regulates the deformed shape of the first reinforcing layer 2a. Therefore, the first reinforcing layer 2a is also unlikely to collapse. In this way, this elastic contraction body can improve the performance efficiency while preventing the reinforcing layer from being broken, and thus can maintain the high performance for a long period of time.

Next, the rate of improvement in performance efficiency by dividing the reinforcing layer into two layers will be described.

Generally, when the reinforcing layer is made into a smooth monofilament cord braided structure, the performance efficiency (tensile load) is improved by 20 to 60% over the multifilament twisted cord braided structure. Further, when the reinforcing layer is doubled, the ratio of the tensile load applied to the reinforcing layer is such that when the force applied to the first reinforcing layer 2a which is the inner reinforcing layer is 1, the force applied to the second reinforcing layer 2b is 1/2. Become. Therefore, the strength required for the second reinforcing layer 2b is half that of the first reinforcing layer 2a. In this way, when the strength of the second reinforcing layer 2b is set to half the strength of the first reinforcing layer 2a, the performance efficiency (tensile load) should be improved by 14 to 40% over the braided structure of twisted cords of multifilament. become. Actually, the frictional resistance between the first reinforcing layer 2a and the inner cylinder 1 is reduced a little more, so that it is further improved. It should be noted that the strength distribution of the second reinforcing layer 2 may be further reduced in order to further improve the performance efficiency, but since the normal reinforcing layer has a safety factor of about 10 times, the first reinforcing layer is When the safety factor of 2a is set to 10, it is possible to set the safety factor of the second reinforcing layer 2b as low as about 2, and in this case, the first reinforcing layer 2a and the second reinforcing layer 2b are The performance efficiency is 18
It can be improved up to about 54%.

(Effect) As described in detail above, the elastic contraction body of the present invention has a smooth braided structure of a monofilament cord with a reinforcing layer made of a braided structure surrounding the inner cylinder made of rubber or a rubber-like elastic body. Since the structure is divided into two layers, the first reinforcing layer composed of the body and the second reinforcing layer composed of the braided structure of the twisted cord of multifilament having unevenness, the knitting does not occur even when used for a long period of time. The drive loss due to the deformation resistance of the reinforcing layer can be reduced, and high performance can be stably obtained for a long period of time.

[Brief description of drawings]

FIG. 1 is a partially sectional front view showing the structure of an elastic contraction body of the present invention, and FIG. 2 is a partially cutaway perspective view showing the structure of the inner cylinder and reinforcing layer of the elastic contraction body of FIG. It is a figure. 1 ... Inner cylinder 2a ... 1st reinforcement layer 2b ... 2nd reinforcement layer 3 ... End closing member 4 ... Caulking cap 5 ... Nipple 6 ... Flange 7 ... Clevis end 8 ... Annular protrusion 9 ... Hole 10 ... Internal cavity 11 ... Connection hole 12 ... Fitting 12a ... Fluid pressure supply port

Claims (1)

[Claims] 1. An inner cylinder made of rubber or a rubber-like elastic body, a first reinforcing layer made of a braided structure of a smooth monofilament cord surrounding the outer circumference of the inner cylinder, and an outer circumference of the first reinforcing layer. A second reinforcing layer made of a braided structure of multifilament twisted cords having irregularities on the surface, end closing members for closing both ends thereof, and fluid pressure supply for supplying fluid pressure into the inner cylinder. An elastic contraction body having a mouth.