JP2558065B2 - Strain removing method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for removing strain after quenching a steel rod, tube or similar elongated article having a circular cross section, such as a drill.

[0002]

2. Description of the Related Art As a conventional method for removing strain after quenching a steel round bar, a round tube or an elongated article having a similar circular cross section, the elongated articles are individually held at both end portions, There were hammering treatment in which strain was taken in the direction of strain removal by hammering to straighten the product, and press tempering treatment in which elongated articles were individually sandwiched in dies and tempered.

[0003]

However, in the hammering process, it is not possible to evenly bend, and there is a risk that a trace of the hammering will remain and there is a risk of cracking. There is a drawback that requires later inspection for the presence of cracks.

In the press tempering treatment, although cracks are not generated, there is a problem that strain cannot be completely removed.

Further, in the conventional strain relief treatment, there is a drawback that the treatment can be performed only individually by any treatment method and the efficiency is low.

Therefore, an object of the present invention is to solve the problems of the conventional strain relief processing and to obtain an efficient and defect-free strain removal method and apparatus.

[0007]

In order to achieve this object, the strain relief treatment method of the present invention provides an individual strip-shaped article having a circular cross-section after quenching to a substantially V shape having a V-shaped tapered bottom wall portion. In a tempering tank having a V-shaped cross section, a filling step of filling a large number of a plurality of pieces arranged in a direction orthogonal to the V-shaped cross section, and a top opening of the tempering tank is closed and a uniform downward direction is applied to the filling. It is characterized by comprising a step of mounting a pressure lid means for applying a pressure on the clamp, and a tempering step of heating the entire tempering tank while a load is applied to the filling by the pressure lid.

Further, the strain relief treatment apparatus of the present invention comprises a bottom wall portion having a V-shaped taper, and a pair of upright portions extending vertically upward from both sides of the V-shaped tapered bottom wall portion in parallel with each other. And a pair of end walls defining the ends of the cavity of substantially V-shaped cross section consisting of these bottom wall and upright,
A tempering tank in which the inner surface of the joint between the tapered bottom wall portion and the upright portion is formed into a smooth curved surface, which is a steel round bar, round tube or similar circular cross-sectional shape after quenching. A tempering tank for arranging a number of the elongated articles in a direction orthogonal to the V-shaped cross section and filling a large number of them, a pressure lid means for closing the top opening of the tempering tank, and a quenching for filling the tempering tank. Of a plurality of individual circular cross-section-shaped articles, the lid clamping means for generating a uniform downward pressure by the pressure lid means, and the pressure lid means for the filling of the tempering tank by the lid clamp means. And a heating unit that heats the tempering tank in a state where a uniform downward pressure is generated.

[0009]

According to the method and apparatus of the present invention, the pressing lid means clamped to the top opening of the tempering tank generates a uniform downward pressure on the whole filling, and the whole filling is the fluid in the closed space. In this case, each elongated article having a circular cross-sectional shape, which is packed in a large amount in the tempering tank, receives uniform pressure from the surrounding elongated articles. In particular, the V-shaped tapered bottom wall generates an oblique reaction force against the downward pressure by the pressure lid, and acts to apply a uniform pressure over the entire circumference of the individual elongated articles.

According to the method and apparatus of the present invention, strain is removed by heating the entire tempering tank in such a state that each elongated article receives equal pressure from the entire circumference.

[0011]

The preferred embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a schematic sectional view of a strain relief device 1 according to the present invention. The apparatus of the illustrated embodiment comprises a bottom wall 2 with a V-shaped taper, uprights 3 extending vertically from both sides of the bottom wall 2 in parallel with each other, and the bottom wall 2 and the upright 3. A tempering tank 5 of substantially V-shape is provided having a pair of end walls 4 (see FIG. 2) defining the ends of the cavity of substantially V-shaped cross section. In addition, the inner surface of the joint between the bottom wall portion 2 and the upright portion 3 is rounded.

The tempering tank 5 is filled with a large number of a large number of steel rods, tubes or similar elongated articles having a circular cross section, such as drill rods 6, which have been quenched.

The top opening in the upright portion 3 of the tempering layer 5 has a uniform downward pressure applied to a long and narrow article having a circular cross section, such as a drill rod 6, which is packed in a large amount in the tempering tank 5. Is closed by a pressure lid means 7 for adding. In order to maintain the pressure closure by the pressure lid means 7, the pressure lid means 7 is clamped on the upright portion 3 by the lid clamp means.

In the illustrated embodiment, the pressure lid means 7 is a crimping portion 8 which has a crimping surface which can be fitted to the inner circumference of the top opening of the upright portion 3 and has a crimping surface for crimping to the surface of the filling assembly. It has a flange portion 9 for supporting the cover member 7 on the upright portion 3. Further, the lid clamp means may have any structure, but in the illustrated embodiment, a headed bolt 11 screwed into the screw hole of the upright portion 3 via the bolt hole 10 (see FIG. 2) provided in the flange portion 9. And

Furthermore, the strain relief device according to the present invention comprises:
A heating means is provided to pressurize the tempering tank 5 in a state where the pressure lid means 7 is pressurized and closed in the tempering tank 5 by the lid clamp means 11. Although not shown, this heating means can be arbitrary, for example, an electric furnace or a salt bath that houses the entire tempering tank 5, and the tempering tank 5 itself is configured as an electromagnetic heating body. You can also do it.

The size of the tempering tank 5 is adapted to the size of the article 6 to be filled. For example, if the circular elongated article to be filled has a diameter (d) of 3.5 to 10 mm and a length (l) of 300 to 400 mm, for example, the height of the upright portion 3 is preferably 30 to 50 mm, and the V-shape is suitable. The maximum depth of the bottom wall with tapered taper 2 is 20
The wall thickness of the bottom wall portion 2 is preferably 0 to 300 mm.
Set to 100 mm. The angle of the V-shaped V-shape is 45 to 70 °, and preferably 60 °. The thickness from the top surface of the pressure lid means to the crimping surface is 25 mm, the width is 250 mm, and the length L (see FIG. 2).
Is 500 to 600 mm.

FIG. 3 shows the pressing lid means 7 in an intermediate state before the clamping is completed by the lid clamping means, that is, the headed bolts 11, and when the clamping is completed, a large amount is filled in the tempering tank 5. The pressure condition applied to each of the elongated articles having a circular cross section, for example, the drill rod 6 is shown. According to the present invention, the elongated cross-section article having a large volume filled in the tempering tank 5 has a downward pressure by the pressure lid means and V
Various oblique reaction forces are applied from the wall surface with the letter-shaped taper, and a situation in which it can be regarded as a fluid filled in the closed space is generated, and the same pressure is applied to the entire circumference of each individual elongated article. Therefore, all the filled elongated articles are in a pressed state in which they are straightly stretched, and in this state, the strain can be removed by heating by the heating means.

Experimental Example 1 A drill rod 6 having the following specifications was oil-quenched at 900 ° C., then a large amount was filled in the tempering tank 5 shown in FIG. It was clamped in the upright portion 3, and then strain relief tempering was carried out by heating in an electric furnace at a temperature of 400 ° C. for 3 hours. Material: Chromium / Molybdenum steel (SCM435) Diameter: 3.5 mm Length: 300-400 mm The experimental results are as follows. Bending deformation after quenching δ ₀ = 0.5 to 1.0 mm Bending deformation after strain relief and tempering δ = 0.0 to 0.02 mm

Experimental Example 2 A shaft (round bar) having the following specifications was oil-quenched at 900 ° C., and then many were filled in the tempering tank 5 shown in FIG. Clamp to the upright part 3,
After that, strain relief tempering was performed by heating at a temperature of 200 ° C. for 3 hours in an electric furnace. Material: Die steel Diameter: 30 mm Length: 500 mm The experimental results are as follows. Bending deformation amount after quenching δ ₀ = 0.7 to 1.6 mm Strain relief Bending deformation amount after tempering δ = 0.0 to 0.03 mm

Experimental Example 3 A pipe having the following specifications was oil-quenched at 850 ° C., then a large amount was filled in the tempering tank 5 shown in FIG. 1, and the same torque was applied to each bolt 11 to make the pressing lid means upright. It was clamped at 3 and then subjected to strain relief tempering by heating in an electric furnace at a temperature of 400 ° C. for 2 hours. Material: Chrome steel (SCR440) Outer diameter: 5 mm Inner diameter: 3 mm Length: 300 mm The experimental results are as follows. Bending deformation amount after quenching δ ₀ = 0.8 to 1.7 mm Strain relief Bending deformation amount after tempering δ = 0.0 to 0.02 mm

Such a strain relief effect cannot be obtained in a tempering tank having only a V-shaped tapered bottom wall or a tempering tank having only upright side walls. That is, it is impossible to generate vertical pressure and various oblique pressures around the individual filled articles.

[0023]

According to the method and apparatus of the present invention, the following effects can be obtained. That is, 1) It is possible to perform uniform strain relief by applying uniform pressure to the entire circumference of each steel circular cross-section elongated article to be strain-relieved, and there is no need to inspect for cracks after treatment. . 2) It is possible to perform strain relief processing for a large number of articles at once, instead of individual articles. 3) In the conventional cold strain relief of the pipe, the inner diameter is not deformed while the inner diameter is strained even if the outer diameter can be strained. 4) While the conventional cold strain relief treatment leaves indentations for strain relief, no indentation remains at all.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a strain relief device of the present invention.

FIG. 2 is a plan view of a tempering tank of the apparatus shown in FIG.

FIG. 3 is a diagrammatic explanatory view for explaining the operation of the strain relief device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Strain removing device 2 Bottom wall part 3 Upright part 4 End wall 5 Tempering tank 6 Drill rod (circular cross-section elongated article) 7 Pressurizing lid means 8 Crimping part 9 Flange part 10 Bolt hole 11 Headed bolt

Claims (4)

(57) [Claims] 1. A strain relief method performed after quenching a steel round bar, a round tube, or a similar elongated article having a circular cross section, wherein the individual elongated articles having a circular cross section after quenching are V-shaped. A filling step of filling a large number of tempering tanks having a substantially V-shaped cross section having a tapered bottom wall in a direction orthogonal to the V-shaped cross section, and closing and filling the top opening of the tempering tank. It comprises a step of clamping a pressure lid for applying a uniform downward pressure to the object, and a tempering step of heating the entire tempering tank while applying a load to the filling material by the pressure lid. Strain removal method. 2. A bottom wall portion having a V-shaped taper, a pair of upright portions extending vertically upwards from both sides of the tapered bottom wall portion, and a pair of upright portions substantially comprising the bottom wall portion and the upright portion. A temper having a pair of end walls defining the ends of a cavity of V-shaped cross section, the inner surface of the joint between the V-shaped tapered bottom wall and the upright being formed into a smooth curved surface. A tempering tank for aligning and filling a large number of steel rods, round tubes or similar elongated articles having a circular cross section after quenching in a direction orthogonal to a V-shaped cross section, Pressurizing lid means for closing the top opening of the tank, and lid clamping means for generating a uniform downward pressure by the pressure lid means on a large number of individual tempered circular cross-section-shaped articles filled in the tempering tank. And the lid clamp means causes the pressure lid means to burn Strain relief device characterized by comprising a heating means for heating the tempering tank while generating a downward uniform pressure against and tank packing. 3. The strain relief device according to claim 2, wherein the V-shaped apex angle of the bottom wall with the V-shaped taper is 45 ° to 70 °. 4. The strain relief device according to claim 2, wherein the V-shaped apex angle of the V-shaped tapered bottom wall is 60 °.