JP7441674B2 - robot arm - Google Patents

Description

The present invention relates to a robot arm formed by joining a cylindrical body made of FRP (fiber reinforced plastics) to a metal flange.

Generally, industrial robots used for laser processing, etc., require a tip precision of about 1/100 mm, and for this purpose, high rigidity is required. In contrast, in recent years, with the progress of the declining birthrate and aging of the population, there has been an increasing need among humans for industrial robots that operate together with or assisting humans. Such industrial robots do not need to have the same high rigidity as conventional industrial robots, but rather are strongly desired to be lightweight from the viewpoint of energy conservation and global environmental conservation. As one means of achieving this, it has been considered to replace the main body portion of the robot arm with an FRP cylinder. At that time, there are various types of reinforcing fibers to be used, such as carbon fiber, glass fiber, aramid fiber, etc., but among these, carbon fiber, which is particularly excellent in terms of specific strength and specific modulus, is used for reinforcing. CFRP (carbon fiber reinforced plastics), which is made of fiber, is considered to be a promising choice.

A robot arm whose main body is a cylinder made of FRP needs to have functional parts attached to the main body so that it can perform various functions. Attaching the functional parts to the main body made of the FRP cylinder requires a joining method that balances the torsional strength of the FRP cylinder.

Patent Document 1 discloses that, in a mechanical device part in which a metal joint is press-fitted into the end of an FRP cylinder, the FRP cylinder can be used to press-fit the metal joint while ensuring the required high torsional strength. Our goal is to provide a structure that can prevent damage from occurring at the end of the body and also prevent the progression of deterioration at that part. A mechanical device part with a manufactured joint is disclosed, which is characterized in that a slit is formed in the axial direction from the end face of an FRP cylindrical body.

Japanese Patent Application Publication No. 2006-103032

However, the mechanical device component disclosed in Patent Document 1 is made by press-fitting a convex ring integral with a metal joint into the end of an FRP cylinder, and there is a problem that sufficient joint strength cannot be obtained. . In addition, in order to obtain sufficient joint strength, it is necessary to increase the length of the convex ring that is press-fitted into the FRP cylinder, and in that case, the weight of the entire metal joint becomes excessive, making it impossible to reduce the weight sufficiently. There are also problems.
In view of the above-mentioned problems in the conventional technology, the present invention has been developed by attaching a functional part to the main body part of a robot arm whose main body part is a cylinder made of FRP, while ensuring the required high torsional strength. Moreover, it is an object of the present invention to provide a robot arm that is highly safe as a robot arm that operates among humans, together with humans, or while assisting humans.

That is, in the robot arm according to the present invention, a metal ring having a compression elastic modulus equal to or higher than that of the FRP cylinder is attached to the inside of the FRP cylinder at the joint between the FRP cylinder and the metal flange. , the FRP cylinder and the metal flange are joined by tightening the outer periphery of the FRP cylinder with a metal flange.
When the metal flange is fastened to the outer periphery of the FRP cylinder in this manner, the length of the metal flange in the axial direction of the FRP cylinder can be reduced, and the weight can be reduced.

By applying an adhesive between the metal flange and the FRP cylinder and fastening the metal flange to the outer periphery of the FRP cylinder, the mutual fastening force can be strengthened.

By making the outer diameter of the metal ring at room temperature larger than the inner diameter of the FRP cylinder, it is possible to increase the stress acting on the outer circumferential direction of the FRP cylinder, and as a result, the stress between the FRP cylinder and the metal flange can be increased. The tightening force will be increased.

Furthermore, by cooling the metal ring and attaching it, it is possible to prevent damage to the FRP cylindrical body that would otherwise occur when mechanically press-fitting with a large pressure.

The torsional strength can be increased by fastening the FRP cylinder, the metal flange, and the metal ring with a through screw.

For the FRP cylinder, it is particularly preferable that the reinforcing fibers include at least carbon fibers having excellent specific strength and specific modulus from the viewpoint of high strength and torsional torque transmission characteristics.

According to the robot arm of the present invention, the robot arm is sufficiently lightweight while ensuring the required high torsional strength, and is highly safe as a mechanical device that operates between, with, or assisting humans. It can be done.

FIG. 1 is a perspective view of a robot arm according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the robot arm of FIG. 1; 3 is a sectional view taken along line AA in the partial sectional view of FIG. 2. FIG. FIG. 2 is a partially exploded perspective view of the robot arm of FIG. 1; FIG. 2 is another partially exploded perspective view of the robot arm of FIG. 1; FIG. 2 is another partially exploded perspective view of the robot arm of FIG. 1; FIG. 2 is yet another partially exploded perspective view of the robot arm of FIG. 1;

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a robot arm 1 according to an embodiment of the present invention.
The robot arm 1 is constructed by attaching a pair of separable metal flanges 3a and 3b made of aluminum alloy to an FRP cylinder body 2, which is one embodiment of an FRP cylinder body. Each of the pair of separable metal flanges has an inner periphery that divides a circle into two. The metal flanges 3a, 3b function as joints with, for example, an operating part, a grip part, a joint part, etc. (not shown).

As shown in FIGS. 2 to 7, the inside of the FRP cylinder 2 at the joint between the FRP cylinder 2 and the metal flanges 3a and 3b has a compressive elastic modulus equal to or higher than that of the FRP cylinder 2. A metal ring 4 is attached. In this state, the outer periphery of the FRP cylindrical body 2 is tightened using metal flanges 3a and 3b. As a result, the FRP cylindrical body 2 and the metal flanges 3a, 3b are joined in such a manner that the side wall of the FRP cylindrical body 2 is sandwiched between the metal flanges 3a, 3b and the metal ring 4. At that time, a commercially available adhesive is interposed in advance between the metal flanges 3a, 3b and the outer circumference of the FRP cylinder 2, and the outer circumference of the FRP cylinder 2 is tightened and fastened by the metal flanges 3a, 3b. The fastening force can be strengthened. As a mode of interposing the adhesive material, it is possible to apply a fluid adhesive or arrange a sheet-like adhesive.
When the metal flanges 3a and 3b are fastened at the outer circumferential portion of the FRP cylinder 2 in this way, a convex ring integrated with a metal joint is press-fitted into the end of the FRP cylinder 2 as shown in the conventional patent document 1. Compared to the embodiment, the lengths of the metal flanges 3a and 3b in the two axial directions of the FRP cylinder can be made smaller, and the weight can be reduced.

The outer diameter of the metal ring 4 at room temperature is set to be larger than the inner diameter of the FRP cylindrical body 2. As a result, the stress acting from the metal ring 4 toward the outer circumferential direction of the FRP cylinder 2 can be increased, and as a result, the fastening force between the FRP cylinder 2 and the metal flanges 3a and 3b is increased.

Furthermore, even if the outer diameter of the metal ring 4 at room temperature is made larger than the inner diameter of the FRP cylinder 2, the metal ring 4 can be cooled and attached to the inside of the FRP cylinder 2 so that large pressure can be applied. Damage to the FRP cylindrical body 2 that occurs when mechanically press-fitting can be prevented.

The FRP cylindrical body 2, the metal flanges 3a, 3b, and the metal ring 4 are fastened with through screws 5, 5, . . . . This allows the torsional strength to be increased.

For the FRP cylinder 2, it is particularly preferable that the reinforcing fibers include at least carbon fibers having excellent specific strength and specific modulus, from the viewpoint of high strength and torsional torque transmission characteristics.

In addition, although the case where the FRP cylinder body 2 is used has been described in the above embodiment, the FRP cylinder body is not limited to a cylinder body, and depending on the embodiment, an elliptical cylinder body, a mode in which the top of the corner of a square cylinder is chamfered, etc. are adopted. can do.

DESCRIPTION OF SYMBOLS 1... Robot arm, 2... FRP cylindrical body, 3a, 3b... Metal flange, 4... Metal ring.

Claims (4)

It is a metal joint that is attached to the end of the FRP cylinder, and is attached to the inside of the FRP cylinder at the joint between the FRP cylinder and a pair of separable metal flanges that are mutually fastened with screws. , a metal ring having a compressive elastic modulus equal to or higher than that of the FRP cylinder is attached, and the pair of metal flanges is tightened around the outer periphery of the FRP cylinder, so that the FRP cylinder and the pair of metal A robot arm, characterized in that the FRP cylinder body, the metal flange, and the metal ring are fastened together with a through-screw . The robot arm according to claim 1, wherein each of the pair of separable metal flanges has an inner periphery that divides a circle into two. The robot arm according to claim 1 or 2, wherein the outer diameter of the metal ring at room temperature is larger than the inner diameter of the FRP cylinder. 4. The robot arm according to claim 3, wherein the metal ring is cooled and mounted.

Images