JPH0529371Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fastening structure for integrally fastening objects to be fastened, such as gears and cams, to a shaft.

[Conventional technology]

Conventionally, an object to be fastened, such as a gear or a cam, and a shaft have been formed separately, and welding or brazing has generally been used as a means for fastening the two together.

However, with the welding method described above, not only may thermal distortion occur due to the heat during welding, but also the materials that can be used are limited, and with the welding method, the material that can be used is limited, and the material that can be used is limited. Due to annealing of the fastened objects such as gears,
This curing method had the disadvantage of being difficult.

For this reason, for example, Japanese Utility Model Application Publication No. 55-163533 discloses an inner cylinder that fits around the shaft and has an open part in a part, and an outer cylinder that fits over the inner cylinder and has an open part in a part. The nuts are made to contact each other with their tapered surfaces, and are screwed into the threaded portion formed by extending the small diameter portion of the inner cylinder, so as to be able to abut on the end face of the outer cylinder, and furthermore, a plurality of bolts are screwed through the nuts. The rotating body fixing tool is made by Jitsukaiaki.
Publication No. 57-167903 discloses a key in which a key made of a shape memory alloy is inserted into a keyway provided between a first and second mechanical part, and is heated appropriately after insertion.
Furthermore, International Publication No. 84104367 pamphlet (1984) proposes a joint structure in which a tapered piston is slid and fixed by pressurized liquid.

[Problem that the invention attempts to solve]

However, the method described in the above-mentioned Japanese Utility Model Publication No. 55-163533 is not only structurally complex and difficult to manufacture, but also has a limited fastening force and is susceptible to loosening after long-term use. It is thought that this may occur and reduce the fastening force.
In the key described in Japanese Patent No. 57-167903, the key itself is made of an expensive shape-memory alloy, which not only leads to high costs, but also does not provide much expected fastening force.

Furthermore, the method disclosed in International Publication No. 84104367 pamphlet (1984) requires the use of a sealing mechanism to prevent liquid leakage, and has the problem of being expensive in terms of processing.

[Means for solving the problems] In view of the above-mentioned conventional problems, the present invention has a relatively simple structure and can obtain a fairly strong fastening force, and this fastening force can be used for a long time. It was devised to provide a product that not only does not deteriorate due to the vibrations but also can be manufactured at a relatively low cost. When forming the keyway, a pair of wedges is inserted into the keyway with their thick rear ends facing each other, and the shape memory alloy disposed between the rear ends of the wedges is heated. Accordingly, the fastening structure is characterized in that the object to be fastened and the shaft inserted into the attachment hole are connected by the wedge.

[Effect]

Then, the shape memory alloy is returned to its original shape by heating to about 100°C, for example, and the restoring force at this time pushes the rear end of the wedge toward the tip to advance the wedge. The wedge is firmly inserted into the key groove of the object to be fastened, and through this wedge action, the shaft and the object to be fastened are reliably fastened to obtain a strong fastening force.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the embodiment shown in Figs. 1 to 4. In the figures, 1 is a cylindrical shaft, and flat parts 1a and 1a are formed on the upper and lower outer peripheral surfaces of the shaft, respectively. ing. This flat part 1a
This is to prevent the wedge 3 from rotating by seating the lower surface of the wedge 3 on this surface.

Reference numeral 2 denotes a substantially cylindrical gear as an object to be fastened, and a mounting hole drilled in the center of the gear has holes that gradually become deeper toward the center at positions corresponding to the flat parts 1a, 1a of the shaft 1, respectively. Key grooves 2a, 2a each having a mountain-shaped longitudinal section are formed.

3 is a wedge with a rectangular cross section formed so that the tip is thin and the thickness gradually becomes thicker toward the rear end, and the tip is located between the shaft 1 and the keyway 2a of the gear 2.
That is, a total of four pieces are inserted, one pair each facing each other, with their thin parts facing outward.

By the wedge action that causes the wedge 3 to bite between the shaft 1 and the keyway 2a, the shaft 1
and gear 2 are connected.

Reference numeral 4 denotes a thick-walled cylindrical shape memory alloy disposed between the rear ends of the pair of wedges 3, 3, that is, between the thick-walled portions, and is formed into a perfect circle as shown in FIG. 4A.
Thereafter, it is deformed into an elliptical shape as shown in FIG.

This shape memory alloy 4 is arranged in the keyway 2a so that the short axis of the ellipse is in the longitudinal direction of the mounting hole of the gear 2 in the deformed state, and after the shaft 1 is inserted into this mounting hole. , this for example
By heating it to 100℃, it is restored to its perfect circular shape.
This restoring force causes the pair of wedges 3, 3 to move forward through the gap between the keyway 2a and the flat portion 1a of the shaft 1, that is, to move outward, so that the wedges are firmly wedged between the shaft 1 and the mounting hole. The structure is such that this wedge action is made strong and the shaft 1 and gear 2 are reliably fastened together.

The one shown in FIG. 5 shows another embodiment of the present invention, and unlike the previous embodiment, a keyway is not formed in the mounting hole of the gear 2', and the inner periphery of the mounting hole is centered. The wedge 3' is formed into a mountain-like shape 2'a in which the inner diameter gradually increases towards the end, and the upper surface of the wedge 3' is shaped like an arc along the shape of the inner circumferential surface 2'a. This prevents the wedge 3' from rotating due to the rotation of the shaft 1, and the other structures and functions are the same as those of the previous embodiment.

Moreover, what is shown in FIG. 6 shows still another embodiment of the present invention, in which a key groove 2''a whose depth gradually increases in one direction is provided on the inner circumferential surface of the shaft mounting hole of the gear 2''. , 2″a, and this keyway 2″a
A wedge 3 is inserted between the flat part 1'a of the shaft 1', and between this thick rear end part of the wedge and the stepped part 1'b provided on the shaft 1', shape memory alloy 4
The wedge 3 is made to bite into the keyway 2''a by restricting the movement of the shape memory alloy 4 toward the stepped portion 1'b when it is heated and returned to its original shape. It is composed of

Although not shown, a cam may be used as the fastened member in addition to the above-mentioned gear, or a cylindrical connecting member may be used to connect two shafts.

[Effect of idea]

As described above, the fastening structure according to the present invention forms a keyway with a mountain-shaped longitudinal section in the shaft attachment hole of the object to be fastened, and also inserts a pair of wedges in the keyway with their thick rear ends. The object to be fastened and the shaft inserted into the mounting hole are connected by the wedge by inserting the object facing each other and heating the shape memory alloy disposed between the rear ends of the wedges. Therefore, with a relatively simple structure, it is possible to obtain a fairly strong fastening force by increasing the force due to the wedge action during fastening, and since the pressing force of the shape memory alloy is constantly acting, this fastening force can be maintained for a long time. There is no risk of deterioration with use.

Furthermore, since the amount of expensive shape memory alloy used can be minimized, there are various effects such as being able to be manufactured at a relatively low cost.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention,
Figure 1 is a longitudinal front view, Figure 2 is a side view, Figure 3 is a perspective view showing the arrangement of the wedge and shape memory alloy, Figure 4 is a plan view showing the deformed state of the shape memory alloy, and Figure 5. 2 is a diagram corresponding to FIG. 2 showing another embodiment, and FIG. 6 is a diagram corresponding to FIG. 1 showing still another embodiment. 1, 1'...Shaft, 1a, 1'a...Flat portion, 2, 2', 2''...Gear (object to be fastened), 2a,
2'a, 2''a...the same tapered surface, 3, 3'...wedge,
4...Shape memory alloy.

Claims (1)

[Scope of utility model registration request] A keyway having a mountain-shaped longitudinal section is formed in the shaft attachment hole of the object to be fastened, and a pair of wedges are inserted into the keyway with their thick rear ends facing each other, and the above-mentioned rear ends of both wedges are inserted into the keyway. A fastening structure characterized in that the wedge connects the object to be fastened and the shaft inserted into the mounting hole by heating a shape memory alloy disposed between the ends.