JPS60118426A - Method of forming inner diameter section of cylinder - Google Patents

Abstract

PURPOSE:To simply fabricate the bore section of a cylinder having a desired diameter, by fitting the cylinder after heating onto a jig having an outer diameter corresponding to the desired diameter of the bore section of the cylinder, and the by cooling the cylinder to transfer the outer diameter of the jig to the bore section of the cylinder. CONSTITUTION:An expandable collet 13 which is expandable and shrinkable in association with extension and retraction of a drawbar 7, is fitted into the frame bore section 3 of a motor frame 1. After the collet 13 is expanded, the motor frame 1 which is in a thin hollow cylindrical shape is heated by heated blast or electrical heat reflection and is then cooled by coolant so that the high true circularity of the collet 3 may be transferred to the frame bore section 3 by expanding the expandable collet 13 on a mandrel. Thereafter, the frame 1 is removed from the mandrel. With this arrangement, a motor frame having a reproducible inner diameter may be obtained with a high degree of accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for forming the inner diameter of a cylinder to a desired dimension.

[Technical Background of the Invention and its Problems] Some motor frames for small general-purpose motors are formed as thin hollow cylindrical bodies through aluminum extrusion. If a cylindrical body such as such a motor frame is to be used in a rotating electrical machine, the hollow portion, that is, the inner diameter dimension, is required to have highly accurate roundness based on the arrangement relationship with the stator and rotor.

The dimensions of the inner diameter of the cylindrical body will be described below, taking as an example the motor frame formed by the above-mentioned aluminum extrusion process shown in FIGS. 1 and 2.

In FIGS. 1 and 2, reference numeral 1 denotes a motor frame in which cooling fins 2 are provided on the outer peripheral surface of the motor frame.
．． It varies widely from 2 to 0.8 kaku.

In the above, the frame inner diameter 3 is a standard during processing, such as when turning both end faces of the motor frame 1, turning the spigot for attaching the bracket, and press-fitting the stator core into the frame inner diameter 3. This is the part that becomes. Particularly in small-sized rotating electric machines such as servo motors that are frequently used these days, a high degree of circularity is required for the motor frame. In this case, if the roundness of the frame inner diameter 3 is poor, it may become impossible to manually insert the stator core into the processing jig, or there may be jamming between the frame inner diameter 3 and the stator core when press-fitting the stator core. Alternatively, phenomena such as galling may occur, resulting in problems such as reduced press-fitting workability and poor concentricity between the stator core and the frame inner diameter 3.

In order to eliminate the above-mentioned problems, as a method for correcting the roundness of the frame inner diameter 3, a correction mandrel 5 having a press-fitted taper 4 provided in the frame inner diameter 3 of the motor frame 1 is conventionally used as shown in FIG. The inner diameter of the motor frame 1 is expanded by press-fitting it in the direction of the arrow shown in the drawing using a press equipment, etc., and then pulling out the straightening mandrel 5 again using the press equipment or the like in the direction opposite to the arrow shown in the drawing, thereby correcting the roundness. There is a way. The roundness of the motor frame 1 corrected by this conventional method is such that when the straightening mandrel 5 is removed from the motor frame 1 and the roundness is corrected, the motor frame 1 exhibits restorability due to springback, etc. The roundness was slightly lower than that formed when the straightening mandrel 5 was press-fitted, and reliability in terms of accuracy was insufficient.

[Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide a method for forming the inner diameter of a cylindrical body by easily shaping the inner diameter of the cylindrical body to a desired dimension. It's about doing.

[Summary of the Invention] In the method for forming the inner diameter of a cylindrical body according to the present invention, a cylindrical body and a jig having an outer diameter dimension corresponding to a desired dimension of the inner diameter part of the cylindrical body are prepared, and the above-mentioned cylindrical body is The present invention is characterized in that the external dimensions of the jig are transferred to the inner diameter portion of the cylinder by placing the jig at the bottom of the furnace and then rapidly cooling the cylinder.

[Embodiments of the Invention] Hereinafter, a case will be described in which correction of the inner diameter forming method of a cylindrical body according to the present invention and spigot processing of the end face of the cylindrical body are performed by a series of steps.

First, an expandable and retractable mandrel will be described as a correction jig used in this embodiment with reference to FIG. Fourth
The expandable and retractable mandrel shown in the figure (hereinafter referred to as mandrel) is provided with a mounting flange 6A, a rotatable mandrel body 6 with a hollow part formed in the axial direction, and is inserted into the hollow part of this mandrel body 6. A drawbar 7 that can be drawn out in the axial direction, a mounting plate 9 attached to the end of the drawbar 7 with bolts 8, a fixed cone 11 fixed to the mounting plate 9 with bolts 10 and formed with a taper, and this fixed cone. An expansion collet 13 is slidably arranged on the tapered surface of the mandrel body 6 and fixed to the mandrel body 6 by a bolt 12, and a sliding collet 13 is provided on the drawbar 7 and slides in a groove formed in the axial direction of the hollow part of the mandrel body 6. It is roughly composed of keys 14 and the like. And drawbar 7
The expansion collet 13 can be expanded and contracted by pulling out and pulling it out, and can be attached to the frame inner diameter 3 of the motor frame 1. Also, by connecting the mounting flange 6A to a spindle (not shown), the entire mandrel can be rotated. It is now possible to do so.

Next, referring to FIG. 5, the case of spigot machining will be described. That is, the motor frame 1 attached to the mandrel rotates as shown by the arrow 16 with the spin = 5-dollar 15.
The blades 20 and 21 provided on the spigot machining tool rest 18 and the end face machining turret 19 of machining 1117 are used to perform spigot machining of the end opening of the motor frame 1 and cutting of the end face, respectively. ing.

FIG. 6 is a flowchart for explaining an example of this embodiment, and this embodiment will be explained in detail with reference to FIG.

First, in process P1, the mandrel shown in FIG. 5 and the processing machine 17 shown in FIG. If so, preparations for attaching the mandrel to the motor frame 1 are made in step P3. If the above processing is necessary, the processing machine 17 is prepared for processing in step P4. After these steps PR and P4 are completed, the expansion collet 13 of the mandrel is expanded by drawing out and pulling out the dropper 7 in step P5. Then, in step P6, a thin-walled hollow cylindrical motor frame 1 manufactured by aluminum extrusion as shown in FIGS. , heated in the range of 280 to 320°C. Then, in step P6, the heated motor frame 1 is
Shrink fit onto the mandrel shown in the figure and hold for about 40 seconds or more.

Then, in step P9, the motor frame 1 is rapidly cooled with a cooling coolant or a cooling liquid, and the frame inner diameter 3 of the motor frame 1 is restrained by the expansion collet 13 of the mandrel, thereby maintaining the high roundness of the expansion collet 13. It is transferred onto the frame inner diameter 3 of the motor frame 1. The interference in this case can be set in various ways depending on the roundness of the inner diameter 3 of the frame before heating, but in this example, it is set in a range of 0.03 to 0.
．． It is about 06#1I11. Next, in process PIO, it is determined whether or not machining is necessary in the processing machine 17, and if it is, in process Pst, as shown in FIG. 5, the motor frame 1 is
The end face, spigot, etc. are turned, the expansion collet 13 of the mandrel is contracted in step P12, and the motor frame 1 is taken out from the mandrel in step P1a.

According to this embodiment described above, the following effects can be obtained.

■ In this embodiment, by shrink-fitting the motor frame 1 to the mandrel, there is almost no springback of the frame inner diameter after the straightening mandrel is removed, which is a phenomenon often seen in conventional straightening methods, and the inner diameter dimension is A stable and highly accurate motor frame can be obtained.

■ Set the heating temperature of motor frame 1 to 280 to 320℃.
By holding for more than 40 seconds, the motor frame 1
On the other hand, it is possible to obtain an annealing effect that eliminates the processing strain (internal strain) of extrusion molding.

■ According to this embodiment, 0.2 to 0.8#11
Frame inner diameter 3 of motor frame 1 with roundness of 1
is almost 0.1 by applying the correction in this example.
The roundness of the frame inner diameter 3 can be improved to 1/2 to 1/10 compared to before correction.

■ Compared to the conventional method, this method can apply extremely uniform force to the entire frame inner diameter 3 by expanding the expansion collet 13, so it is possible to form the inner diameter with higher precision, and it is more effective than the conventional method. This also allows the use of a thinner motor frame 1, making it an extremely effective molding method for reducing material costs.

■ Unlike conventional straightening methods, it is not necessary to attach and detach the straightening mandrel from the motor frame using press equipment, which reduces the number of handling operations, reduces the burden on the operator, and greatly contributes to improved productivity.

■ Even when turning is required, the motor frame 1 can be easily attached to and removed from the turning machine, and turning can be carried out directly after cooling the motor frame 1, so there is no need to hold intermediate work in progress (which improves management efficiency). etc. can be sufficiently improved.

(2) As the dimensional accuracy of the frame inner diameter 3 of the motor frame 1 improves, the concentricity accuracy of the stator core after press-fitting improves, and therefore, it becomes possible to improve the characteristics of the motor.

In addition to the above-mentioned embodiments, the present invention is also applicable to cylinders outside the motor frames 1 to 9, and the jig can be selected according to the shape and dimensions of the inner diameter of the cylinder. Various modifications can be made without departing from the gist of the invention.

[Effects of the Invention] In the present invention, a cylindrical body and a jig having an outer diameter dimension corresponding to a desired dimension of the inner diameter part of the cylindrical body are prepared, and the above-mentioned body is shrink-fitted into the above-mentioned jig, Then, by rapidly cooling the cylinder, the outer dimensions of the jig can be transferred to the inner diameter of the cylinder, so that the inner diameter of the cylinder can easily be formed into desired dimensions. It is possible to provide a method for forming the inner diameter.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a motor frame as an example of a cylindrical body, Fig. 2 is a front view of the motor frame, Fig. 3 is a diagram for explaining a conventional method for forming the inner diameter of a cylindrical body, and Fig. 4 is a diagram illustrating a conventional method for forming the inner diameter of a cylindrical body. FIG. 5 is a diagram showing a state in which a motor frame is inserted into an expandable and retractable mandrel jig, and FIG. FIG. 6 is a flowchart for explaining one embodiment of the method for forming the inner diameter of a cylindrical body according to the present invention. 1...Motor frame, 2...Cooling fins, 3...
・Frame inner diameter, 6...Mandrel body, 7...Drover, 8...Nut, 9...Mounting plate, 10...
Bolt, 11... Fixed cone, 12 bolt, 13...
- Expansion collet, 14...Sliding key. Applicant's agent Patent attorney Takehiko Suzue 11-

Claims (1)

[Claims] A cylindrical body and a jig having an external dimension corresponding to a desired dimension of the inner diameter of the cylindrical body are prepared, the cylindrical body is placed at the bottom of the furnace in the jig, and then the cylindrical body is rapidly cooled. A method for forming the inner diameter of a cylindrical body.