JPS6195731A - Manufacture of axis with stop ring - Google Patents

Abstract

PURPOSE:To improve the clamping force of a stop ring by inserting a split stop-ring made of shape memory alloy to an axis, and fitting it to the annular groove of the axis as well as cooling them to a specific temperature or less, and then heating them to a prescribed temperature to memorize its shape which is in tight contact with the groove. CONSTITUTION:After forming a coiled spring of small-gauge wire by using a shape memory alloy such as a Ni, Ti alloy, a ring 1 having an effective inner peripheral length equal to the peripheral length of an annular groove of axis 2 is manufactured by cutting said wire. This split stop ring 1 is made deformable by cooling it to the MS point or less in a state of fitting it to the axis 2. Next, the axis 2 is inserted into a hollow cylindrical body 5 having an inner diameter equal to the outer diameter of radially contracted ring 1, and the body 5 is put in a furnace and heated in the nonoxidative atmosphere while keeping the temperature of ring 1 at the inherent Af point or more of ring 1 to make the ring 1 memorize its tightly contacting state. In this way, the clamping force of ring 1 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for manufacturing a shaft with a retaining ring in which a split retaining ring is fitted into an annular groove of the shaft by shape memory heat treatment.

Conventionally, such a shaft with a retaining ring has been made by fitting a split retaining ring made of fine spring steel wire with a circular or rectangular cross section into an annular groove of the shaft. However, since the inner diameter of the split retaining ring is equal to the outer diameter of the annular groove, fitting the split retaining ring into the annular groove of the shaft requires pushing it apart without using a special tool, which reduces work efficiency. There was a problem. Further, depending on the type of retaining ring, when the retaining ring is expanded, the stress applied to the retaining ring becomes excessive, far exceeding the yield point, causing permanent deformation, and the retaining ring may not be able to return to its original shape.

An object of the present invention is to provide a method for manufacturing a shaft with a retaining ring that allows a split retaining ring to be fitted into an annular groove of the shaft without requiring a pushing operation using a tool.

The split retaining ring used in the present invention is made of a thin wire made of a shape memory alloy of nickel-titanium alloy or copper-zinc-aluminum alloy and has a circular or rectangular cross section, and is tightly wound with an inner diameter that is equal to or slightly smaller than the shaft diameter. It is made by winding it into a coiled spring shape and then cutting it one by one into rings with an effective inner circumferential length equal to the circumferential length of the annular groove of the shaft. Next, this split retaining ring is cooled to below its unique Ms point (martensitic transformation start temperature) to make it deformable, and the diameter of the split retaining ring is reduced and fitted into the annular groove of the shaft. The split retaining ring is restrained in a diameter-reduced state and heated and held at a temperature higher than the 'Af point (austenite transformation end temperature), so that the retaining ring memorizes the shape of the retaining ring in close contact with the annular groove of the shaft, and then cooled.

A method of manufacturing a retaining ring material shaft according to the present invention will now be described in detail with reference to the accompanying drawings.

As mentioned above, the split retaining ring 1 is made by cutting a tightly wound coil of thin wire of a shape memory alloy of nickel-titanium alloy or copper-zinc-aluminum alloy into a ring, and its inner diameter is the same as that of the shaft 2. The diameter is equal to or slightly smaller than the outer diameter, so that it can be fitted onto the shaft 2 without being pushed apart. The split retaining ring 1 has a circular or rectangular cross section as shown in FIGS. 2 and 3, and has a split portion 3.
The effective inner circumferential length excluding this split portion 3 is equal to the circumferential length of the annular groove 4 of the shaft 2.

When the split retaining ring 1 is fitted onto the shaft 2, its unique Ms point (
When cooled using a refrigerant below the martensitic transformation start temperature, the split retaining ring l becomes deformable. Then, the diameter of the split retaining ring 1 is reduced until the split portion 3 is closed, and the split retaining ring 1 is fitted into the annular groove 4 of the shaft 2. Next, the diameter of the split retaining ring 1 is reduced.
The shaft 2 is attached to a hollow cylindrical body 5 (Fig. 4) having an outside diameter of 2, that is, an inside diameter equal to the diameter of the annular groove 4 of the shaft 2 plus twice the wire diameter of the retaining ring.
The retaining ring 1 is restrained in a contracted state by inserting one or more of them. This hollow cylindrical body 5 is placed in a non-oxidizing atmosphere furnace, and the tube 1 is heated in the furnace at a temperature higher than its own Af point (austenite transformation completion temperature), for example, 300°C to 500°C for 1 to 5 hours. Hold the retaining ring 2 to memorize the state in which it is in close contact with the groove 4 of the shaft. The jig for the hollow cylindrical body 5 is taken out from the furnace, and after cooling, the retaining ring material shaft is taken out from this jig.

As described above, according to the present invention, a split retaining ring having an inner diameter larger than the annular groove of the shaft is formed in advance, the split retaining ring is fitted onto the shaft, and is contracted by a cooling action so as to come into close contact with the annular groove, and this state is then heated. This is a retaining ring that holds the split retaining ring in close contact with the annular groove of the shaft by memorizing the retaining ring. After adjusting the diameter and attaching it to the groove, when it is held above the Af point, it returns to the memorized shape and can exert a strong and sufficient tightening force. In the case of ordinary spring steel, when the diameter is expanded to the shaft diameter, a yielding phenomenon occurs and permanent deformation remains, making it impossible to obtain sufficient tightening force.

[Brief explanation of the drawing]

Figure 1 is a side view of the shaft fitted with the split retaining ring, Figures 2 and 3 are front and side views of the split retaining ring, respectively, and Figure 4 is the split retaining ring fitted into the annular groove of the shaft. FIG. 1 split retaining ring, 2 shafts. 3 split part, 4 annular groove. 5 Hollow cylindrical body. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A thin wire with a circular or rectangular cross section made of a shape memory alloy of nickel-titanium alloy or copper-zinc-aluminum alloy has an inner diameter equal to or slightly smaller than the outer diameter of the shaft and an effective inner diameter equal to the circumferential length of the annular groove of the shaft. A split-shaped retaining ring with a circumferential length is formed, this is fitted onto a shaft, and the split-shaped retaining ring is made deformable by being cooled to below its unique Ms point (martensitic transformation starting temperature), and the diameter of the split-shaped retaining ring is reduced. It is fitted into the annular groove of the shaft, and the split retaining ring fitted in the annular groove is restrained in a reduced diameter state, heated and held at a temperature higher than the Af point (austenite transformation end temperature), and tightly attached to the annular groove of the shaft. A method for manufacturing a shaft with a retaining ring, which comprises cooling the shaft after memorizing the shape.