JPH0616964B2 - How to make a coil - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a coil, and more particularly to a method for manufacturing a coil in which there is no residual stress inside a spring back and a material and high accuracy is obtained.

[Conventional technology]

The "coil" in the present invention is a generic term for a spirally formed conductive material or the like as described in the following examples, as well as an electric heating element, an inductance, or a spiral-shaped object such as a helical spring. Is. A conventional method for manufacturing a coil-shaped product such as a coil and a spring is to wind a wire around a rotating shaft. With this manufacturing method, there is no particular problem in the case of a wire rod having a circular cross-sectional shape of the workpiece, but as shown in FIG. 8, in the case of a rectangular wire rod 1, as shown in FIG. When the coil 2 is wound into a coil shape, the inner peripheral surface 3a side becomes thicker and the outer peripheral surface 3b side becomes thinner, so that a large gap is often formed in the outer peripheral surface 3a. In the figure, t is the coil thickness.

Therefore, the amount of difference in wall thickness between the inner and outer peripheral surfaces 3a and 3b was previously measured and measured for each coil material, and the wall thickness shown in FIG. 10 was reversed based on the value. The trapezoidal wire rod 1 called a bucket shape is specially made by pulling it out with a die.

According to this method, a coil having a correct rectangular cross section can be obtained as shown in FIG.

[Problems to be solved by the invention]

However, in the above-described manufacturing method, since the die drawing process is indispensable for forming the wire rod 1 into the bucket-shaped cross-sectional shape, it takes a lot of time and labor and becomes an expensive coil.

Furthermore, when the shaft around which the wire 1 is wound is removed, a twist release phenomenon called "springback" occurs due to this type of processing, the coil pitch and diameter change, and the relative positions of the winding start and winding end also change. , It is difficult to obtain a high-precision coil. As shown in FIG. 12, the cross section of the wound wire rod 1 has an inner peripheral surface 3 with the neutral axis 4 as a boundary.
Compressive stress 5a on the a side, tensile stress 5b on the outer peripheral surface 3b side
Has the drawback that residual stress remains there even under no load.

In addition, it is difficult to integrally provide a tubular deformed portion other than the coil at both ends of the coil, the central portion, or the like.

On the other hand, it is conceivable to manufacture the coil using cutting, but the conventional idea is to fit a core metal into a hollow cylindrical processed product with a wall thickness that matches the thickness of the coil, and then Will be cut into a coil. However, in this method, the core metal often does not come off due to burrs or plastic deformation during processing, and it is not possible to deform the coil itself to obtain a highly accurate coil.

As described above, the conventional method of manufacturing a coil is not conceivable except for casting, etc., without using a cored bar. However, it is inherently difficult to demand high precision for the coil made by such casting. There is a demand for a method of easily producing a highly accurate coil without involving complicated steps.

It is an object of the present invention to provide a coil manufacturing method capable of processing a spiral groove with high accuracy without using a core metal and without causing a springback and residual stress inside the material.

[Means for solving problems]

In order to achieve the above object, the present invention has a predetermined coil thickness t.
A rotating tool on the inner peripheral surface or the outer peripheral surface of the hollow cylindrical workpiece having a thickness 1 obtained by adding the finishing allowance a to the revolving state while cutting to a depth T of a predetermined coil thickness t or more and a predetermined pitch. A spiral groove is created by feeding with p, and then the finishing allowance a is removed from the other surface of the hollow cylindrical workpiece in which the spiral groove is not created, and a predetermined coil thickness t is obtained. It is characterized in that a coil having a rectangular cross section is created.

[Action]

The principle of the present invention will be described below. FIG. 2 explains the principle of manufacturing the rectangular cross-section coil of the present invention in terms of geometrical dimensions, and shows a partial cross-sectional view of the hollow cylindrical workpiece 8 in the state where the spiral groove 9 is processed. In the present invention, as shown in FIG. 2, first, the wall thickness l of the hollow cylindrical workpiece 8 having an outer diameter D is obtained.
Is thicker than a predetermined coil thickness t in advance. The depth T of the spiral groove is also set to a value equal to or larger than the thickness t of the coil. However, the dimensional relationship is set so that the finishing allowance a remains on the inner peripheral surface even after the spiral groove is processed. Set. The size relationship in the normal case is given by the following equation.

Depth T of spiral groove ≧ thickness t of coil> finishing allowance a By setting in this way, the finishing allowance a part left on the inner peripheral surface at the time of processing the spiral groove is a core metal made of the same material as the coil, and the spiral. It can fulfill the dual role of connecting the grooves, withstand the cutting resistance during cutting, suppress deformation, and prevent deformation such as spring back because it is not cut and separated as a coil from the beginning. . After the creation of the spiral groove,
The finishing margin a is removed from the surface of the hollow cylindrical workpiece on the opposite side where the spiral groove is not created, in this case, the inner diameter side, so as to extend beyond the bottom of the groove. In this way, it is possible to create a highly accurate coil having a rectangular cross section with a predetermined coil thickness t. During the processing of the spiral groove, the occurrence of burrs is much less than in the case where the coil is cut and separated from the beginning.

FIG. 3 shows the tool 7 based on the geometrical dimensional relationship described above.
Is a plan view showing a state in which a spiral groove is cut by cutting the outer periphery of the hollow cylindrical workpiece 8 by a depth T, and the tool 7 revolves around the outer periphery of the hollow cylindrical workpiece 8 while rotating n. N
At the same time, it is shown that a spiral groove is created by feeding at a predetermined pitch p.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 4. FIG. 1 is a partial perspective view. A tool 7 attached to a spindle 6 such as a machining center is rotating, and the outer peripheral surface of the workpiece 8 is cut into the outer peripheral surface of the hollow cylindrical workpiece 8 by a depth T equal to or greater than the thickness t of the coil. It is sent along a predetermined pitch p in the axial direction while revolving along. The thickness 1 of the hollow cylindrical workpiece 8 is usually several millimeters thicker than the notch t, and as shown in the plan view of FIG. .

After processing the spiral groove 9 having the depth T on the outer peripheral surface of the hollow cylindrical workpiece 8, the fourth groove is formed in order to complete the spiral groove 9 as a coil.
In the partial cross-sectional view shown in the drawing, a jig 10 having an inner diameter that fits the outer diameter of the coil is fitted, and a finishing allowance a on the inner peripheral surface of the coil is cut by feeding it with a boring tool 11 by feeding f. Since the incision of the boring tool 11 at this time is the finishing allowance a of an amount smaller than the depth T of the spiral groove, light cutting is performed, and in comparison with the case where the spiral groove 9 is cut and separated as a coil from the beginning, The occurrence of burrs is much less. The jig 10 restrains the outer peripheral surface of the coil so that the coil does not expand in the outer diameter direction after being separated, and the projecting edge 10a of the jig 10 presses the coil end surface 12 to separate the coil. The coil is prevented from extending in the axial direction.

In this embodiment, the spiral groove 9 can be started to be ground from any position on the outer peripheral surface of the hollow cylindrical workpiece 8 and can be similarly ground to any position. Therefore, as shown in FIG. 1, it is possible to leave a portion 18 where the coil is not processed at the end portion of the coil, or a portion where the coil is not processed at the central portion sandwiched by the coil, and various types of coil designs are possible. It is possible to meet the demand for various coil shapes.

In the conventional method of winding the wire rod, it is necessary to join the cylindrical parts other than the coil by welding or adhesion, and there was a problem in the strength of the joint part. It is also free from damage and adhesive deterioration problems. Moreover, not only the pitch and the number of turns of the spiral groove 9 can be freely changed by using the helical cutting function of the NC machine tool of simultaneous three-axis control as it is, but the unnecessary portion is only removed from the cylindrical workpiece. The stress is low, and the spring back is almost zero, so that a highly accurate coil can be obtained. Since the trapezoidal shape of the coil cross section, which is a problem in the winding method of the wire rod, does not occur, the gap between the coils becomes uniform.

As described above, in the present embodiment, the rotating tool is revolved along the outer peripheral surface of the hollow cylindrical workpiece to create the spiral groove, which is then cut off as a coil. Since the cutting is performed with the processing accuracy, it is possible to obtain a coil with high accuracy and without springback and with little residual stress. The pitch can be freely selected, and a shape other than the coil can be integrally provided at any place such as an end portion or a central portion of the coil.

Next, another embodiment of the present invention will be described.

The same parts as those in FIGS. 1 and 4 of the above embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 5, the end mill 17 is rotated, the hollow cylindrical workpiece 8 is also rotated, and the shaft (X
FIG. 11 is a perspective view showing a state in which the spiral groove 9 having a pitch p is processed by feeding in the −X) direction. In this case the spiral groove 9
Width w is defined by the diameter of the end mill 17.

In the above description, the case where the spiral groove 9 is machined on the outer peripheral surface of the hollow cylindrical workpiece 8 is taken as an example, but FIG. 6 shows the case where the spiral groove 9 is machined on the inner peripheral surface of the hollow cylindrical workpiece 8. It shows another embodiment. The tool 7 having a diameter smaller than the inner diameter d of the hollow cylindrical workpiece 8 is rotated and revolved along the inner peripheral surface. FIG. 7 is an explanatory view showing a state of FIG. 6 viewed from directly above, and the spiral groove 9 is processed on the inner peripheral surface while leaving the finishing allowance a on the outer peripheral surface. To remove the finishing allowance a on the outer peripheral surface, a jig (not shown) is fitted on the inside contrary to the one shown in FIG. 6, and the outer peripheral surface of the outer peripheral surface is restrained while restraining the axial and radial deformations. Perform processing.

Although FIGS. 1 and 7 show an example using a multi-blade tool, it goes without saying that a single-blade tool such as a cutting tool may be rotated. A disc-shaped grinding wheel may be used instead of the cutting tool.

〔The invention's effect〕

As described above, according to the present invention, a spiral groove is formed in a hollow cylindrical workpiece having a thickness obtained by adding a finishing allowance to a predetermined coil thickness, and then the finishing allowance is removed to produce a coil. Since it is possible to process a highly accurate spiral groove without using a cored bar, there is no need to process the cored bar, and it is extremely easy to manufacture, yet it is highly accurate and has no springback or residual stress. A coil can be obtained.

[Brief description of drawings]

1 and 4 are explanatory views showing each step of the method for manufacturing a coil which is an embodiment of the present invention, FIGS. 2 and 3 are views showing the principle of the present invention, and FIGS. 5 to 7 FIG. 8 is an explanatory view showing another embodiment of the present invention, and FIGS. 8 to 12 are explanatory views showing a conventional coil manufacturing method. 7: Tool, 8: Hollow cylindrical workpiece, 9: Spiral groove, 10 ... Jig, 11 ... Boring tool, 12 ... Coil end face, 17 ... End mill, 18 ... Coil processing Nothing, N ... Revolution, D ... Outer diameter t ... Coil thickness, a ... Finishing allowance T ... Depth of cut, depth of spiral groove, w ... Width of spiral groove, p ... Pitch , L ... wall thickness, n, n '... rotation, f ... feed.

Claims (3)

[Claims] 1. A tool that rotates on the inner peripheral surface or the outer peripheral surface of a hollow cylindrical workpiece having a thickness (l) obtained by adding a finishing allowance (a) to a predetermined coil thickness (t) has a predetermined coil thickness. (t) or more
(T) Revolves in the state of being cut, and creates a spiral groove by sending at a predetermined pitch (p), and then from the other surface that does not create the spiral groove of the hollow cylindrical workpiece. Removed the above finishing allowance (a) and given the coil thickness (t)
A method of manufacturing a coil, wherein a coil having a rectangular cross section is created. 2. The method for producing a coil according to claim 1, wherein the hollow cylindrical workpiece is fed at a predetermined pitch instead of the tool. 3. The coil manufacturing method according to claim 1, wherein the spiral groove is created while rotating the hollow cylindrical workpiece.