JPH0635616B2 - How to insert a circular saw - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a method for forming a circular saw material having a disc shape in a circular saw manufacturing process.

b. Conventional technology In general, when a force is applied to a material, a certain amount of deformation occurs, but when the applied force is gradually increased, the amount of deformation increases correspondingly. However, depending on the shape of the material and how the force is applied, when the applied force reaches a certain level, a phenomenon in which the deformation suddenly shifts to a completely different deformation from the previous deformation, that is, a buckling phenomenon occurs.

In the case of a circular saw, the buckling phenomenon described above may occur due to thermal stress. The mechanism of this buckling phenomenon is as follows.

That is, frictional heat is generated in the outer peripheral portion of the circular saw when the circular saw is used to rotationally cut an object to be cut such as wood and wood materials (including plastic). Since frictional heat is not generated at all, a relatively large temperature gradient is generated between the outer peripheral portion and the inner peripheral portion of the circular saw. Then, due to the frictional heat generated in the outer peripheral portion, the portion in the vicinity of the blade portion of the circular saw tries to extend in the outer peripheral portion, but it cannot extend due to the resistance of the inner peripheral portion, so that a tensile force is applied to the inner peripheral portion, As a reaction thereof, a compressive stress is generated on the outer peripheral portion. Therefore, the rate of expansion between the outer peripheral portion and the inner peripheral portion of the circular saw is greatly different, and as the outer peripheral portion expands, compressive stress is generated in the outer peripheral portion and tensile stress is generated in the inner peripheral portion. A stress gradient is created between the outer circumference and the inner circumference of the circular saw.

When the thermal stress becomes large and the outer circumference of the circular saw rises to a certain temperature, what has been planarly expanded and contracted until then suddenly changes to another type (for example, as shown in FIGS. 8 and 9). As described above, the circular saw a is dented like a plate or is deformed into a wavy shape. If such deformation or buckling occurs, the circular saw will no longer be able to cut, which will interfere with the cutting work.

Therefore, in order to prevent the occurrence of buckling due to frictional heat as described above, the circular saw material is subjected to waist insertion processing.
This waist insertion process is performed by subjecting a suitable circular ring portion of the circular saw material to plastic expansion processing, whereby a tensile internal force is applied in the circumferential direction at the outer peripheral portion of the saw blade and saw stress is generated as thermal stress during cutting. The tangential compressive stress generated in the outer peripheral portion of the blade is canceled, and buckling is effectively prevented.

As this type of waist insertion method, a hammer striking method in which a worker hits the plate surface of a circular saw material with a hammer to perform plastic expansion processing, or a metal roller is applied to both sides of the circular saw material, respectively. Hold the pair of metal rollers firmly
A roller processing method of pressing and performing plastic expansion processing has been conventionally performed.

c. Problems to be Solved by the Invention However, the conventional hammering method and roller pressing method, which are the conventional hip insertion methods described above, have major problems as described below.

First of all, in the case of the hammering method, a great deal of intuition and knack are required for the work of hitting a circular saw material with a hammer to perform plastic expansion processing on a predetermined waist insertion part, especially on the entire processed surface. Since it requires many years of experience and skill to obtain uniform lumbar strength, it was difficult to save labor and automate the manufacturing process of the circular saw. In addition, even a sufficiently skilled person has a very poor workability and it is difficult to obtain a homogeneous product, so that it is not possible to mass-produce a good-quality circular saw at a low price.

Next, in the case of the roller pressing method, it does not require intuition or tips as compared with the hammer hitting method, but when performing plastic expansion processing on the waist insertion part using a metal roller, preprocessing (circular saw material Of rotary grinding for manufacturing) is likely to be affected, and local strength of hip insertion is likely to occur. Therefore,
In many cases, the lumbar insertion strength becomes non-uniform over the entire surface to be machined. In such a case, the roller pressure was repeatedly applied repeatedly, or the hammering method described above was used together. . For this reason, there are major problems that the production efficiency is extremely low and that it is difficult to obtain a uniform waist strength under certain processing conditions.

The present invention has been made in view of the actual situation as described above, and the object thereof is to efficiently carry out circular saw insertion work without requiring any skill such as intuition or tips.
An object of the present invention is to provide a waist insertion method capable of labor saving and automation.

d. Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, in the waist inserting method performed in the manufacturing process of the circular saw, the central portion and the outer peripheral portion of the disc-shaped circular saw material are used. The shot grains are projected onto the entire area on the inner diameter side from a predetermined area between the central portion and the outer peripheral portion of the circular saw material, or an annular area extending in a strip shape along the entire circumference along a predetermined area between As a result, a compressive stress is generated in the circumferential direction of the region, and in response, a tensile internal force along the circumferential direction is applied to the region on the outer peripheral side of the region.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 shows a shot peening apparatus 1 for carrying out a waist insertion method according to the present invention.
Is a holding jig 3 for holding a circular saw blank 2 which is a workpiece, and a drive mechanism 4 for rotationally driving the holding jig 3.
And a device body 6 including a shot grain projection mechanism 5.

The apparatus main body 6 described above is provided with a vertical rigid housing 9 having chambers 8a and 8b divided into upper and lower stages, and a holding mechanism 3 is arranged on a partition wall 10 of the housing 9, and the holding mechanism 3 is provided. In relation to the mechanism 3, the drive mechanism 4 is arranged in the chamber 8b below the housing 9. The drive mechanism 4 includes an induction motor 14 that applies a rotational force to a drive shaft 13 via a rotational force transmission mechanism 12 including a belt and a pulley, and the drive shaft 13 is a bearing portion 15 of the holding mechanism 3.
The inside is rotatably inserted, and the tip thereof is connected to the workpiece holding base 16.

As shown in FIGS. 1 to 3, the above-mentioned holding jig 3 includes a base 16, a ring-shaped member 17a vertically fixed on the base 16, and a ring-shaped member 17a. The ring-shaped members 17b that are attached to face each other, and these ring-shaped members
It is composed of a ring-shaped intervening member 18 arranged between 17a and 17b, and a pair of mask plates 19a and 19b attached to both surfaces of the circular saw material 2 on the inner diameter side of the ring-shaped members 17a and 17b.

On the side wall 20 of the chamber 8a above the housing 9, the shot grain projection mechanism 5 described above is arranged. The shot grain projection mechanism 5 of this example is of a centrifugal force type and is provided with a shot grain supply source 21, a shot grain supply pipe 22, a pipe 22 connected to the pipe 22, and a side wall 20 of the housing 9 penetratingly arranged. It comprises a horn-shaped member 23, an impeller 24 rotatably arranged in the horn-shaped member 23, and a motor 25 for rotationally driving the impeller 24 in a vertical plane. As the above-mentioned impeller 24, one having a diameter of 400 mm and eight blades is used.
It is driven to rotate at rpm, which allows, for example, diameter
Shot particles (steel balls) of 0.5 to 1.2 mm are projected into the chamber 8a at a speed of 50 to 60 m / s.

Further, a shot grain discharging hole 28 is formed at an outer edge portion of the partition wall 10 of the housing 9, and a chamber of the housing 9 is formed.
A shot grain guide wall 30 is provided near the inside of the side wall 29 of 8b, and a passage 31 is formed by the side wall 29 and the guide wall 30. At the lower end of the passage 31, a shot particle suction pipe 32 is provided.
Is connected to one end of the tube 32, and the other end of the tube 32 is connected to a separator 33 arranged above the housing 9.
The separator 33 is for separating and ejecting shot particles that have been damaged to the extent that they cannot be reused out of the shot particles that have been projected. Shot grain supply through 21
To be fed back to. Further, a dust collecting device 36 is connected to the horn-shaped member 23 of the shot grain projection mechanism 5 via a suction pipe 35.

Next, a description will be given of the case where the circular saw blank 2 is subjected to waist insertion processing using the shot peening apparatus 1 having the above-described configuration.

First, the circular saw material 2 obtained by sequentially performing the quenching / tempering step and the rotary grinding step is attached to the holding jig 3 of the apparatus body 6 as shown in FIG. Hold on. The circular saw material 2 is attached to the holding jig 3 by applying the outer peripheral edge portion of the circular saw material 2 so as to be coaxial with the ring-shaped member 17a and another ring-shaped member 17b. Is applied to the outer peripheral edge of the other surface of the circular saw material 2 coaxially, and the pair of ring-shaped members 17
The outer peripheral edge portion of the circular saw material 2 and the ring-shaped intervening member 18 arranged on the outer peripheral side thereof are sandwiched between a and 17b, and under this condition, the ring-shaped members 17a and 17b are bolted at several positions.
And nut 39 to fix it (see FIGS. 2 and 3). As a result, the circular saw material 2 is firmly held between the pair of ring-shaped members 17a and 17b. Next, a disc-shaped mask plate 19 having the same size and a diameter smaller than the inner diameters of the ring-shaped members 17a and 17b, respectively.
By arranging a and 19b coaxially on both sides of the circular saw material 2, and by using the center hole 2a of the circular saw material 2, a bolt 40 and a nut can be obtained.
Tighten and fix with 41. As a result, the circular saw material 2 is masked by the ring-shaped members 17a and 17b and the mask plates 19a and 19b except for the predetermined portions A and B.

Then, the circular saw material 2 is attached to the holding jig 3 in a state where only the annular portions A and B are exposed.

In this way, after attaching the circular saw material 2 to the holding jig 3, by operating the induction motor 14,
The holding jig 3 and the circular saw blank 2 are driven to rotate in the direction of arrow S in FIG. Next, the shot grain supply source 21 to the supply pipe 22
Supply a large number of shot particles into the horn member 23 via
A shot grain is projected toward the circular saw blank 2 by an impeller 24 that is rotationally driven at high speed by a motor 25 to subject the annular portions A and B to plastic working. At this time, since the portions of the circular saw material 2 other than the annular portions A and B are completely masked as described above, no plastic working is performed.

As described above, the shot grain projection is stopped after the shot shaving projection for a predetermined time completes the waist insertion process on the annular portions A and B of the circular saw blank 2.

The shot particles that have been projected fall through the holes 28 of the partition wall 10 in the passage 31 of the lower chamber 8b and are transferred to the separator 33 via the shot particle suction pipe 32, and only reusable crushed particles are provided. The separated shot grains are discharged to the outside, and the reusable shot grains are supplied again to the shot grain supply source 21 for reuse.

Next, using the shot peening apparatus 1 as described above,
A specific example of carrying out the waist insertion method according to the present invention is shown below.

Example 1 (1) Material of circular saw material SKS-5 (2) Dimensions of circular saw material Outer diameter 305mm Center hole diameter 25.4mm Plate thickness 2mm Number of teeth 79 (3) Annular part A, B of circular saw material Strip-shaped part from 106 (shot processing part) to 116 mm from the center (4) Processing conditions <a> Shot grain diameter 0.8 mm <b> Shot grain hardness HRC58 <c> Shot grain material Cast steel <d> Shot grain Projection speed 50m / s <e> Shot grain projection angle 90 ° <f> Shot grain projection time 5 minutes <g> Rotational speed of circular saw material 10r.pm Surface of circular saw material obtained by this specific example 1 When the residual stress was measured, the results shown in FIG. 6 were obtained.

As is clear from the measurement results shown in FIG. 6, sufficient compressive stress (negative stress) is generated in the annular portions A and B on which shot grains are projected, that is, the shot peening processed portion L, as shown by the solid line. Is recognized. Then, both of the outer peripheral portion C and the inner peripheral portion D of the annular portions A and B are
It is recognized that tensile stress (positive stress) is generated.
Therefore, it was confirmed that the circular saw material 2 was subjected to ideal waist insertion processing with sufficiently strong waist insertion strength.

That is, even when friction heat of the outer peripheral portion C is generated by the heat generated in the outer peripheral portion C in the vicinity of the outermost periphery where the blade is attached when the circular saw is used and a compressive stress is generated therein, the shot peening process Since the tensile stress is preliminarily applied to the outer peripheral portion C due to the presence of the annular portions A and B to which the compressive stress is applied, the inner diameter portion is thermally expanded without exerting a tensile force, and thus a large stress gradient is obtained. Does not occur. Therefore, the thermal buckling phenomenon of the circular saw can be effectively prevented.

In order to confirm such an effect, the circular saw material obtained in this example was subjected to a clam processing, and a tip blade made of cemented carbide or the like was attached to the outermost peripheral portion thereof, and then a cutting test was conducted. The abnormal phenomenon of thermal buckling did not occur at all, and the durability was the same as that of the waist insert processed product by the conventional hammering method or roll processing method, and good results were obtained. It should be noted that, in the above-described specific example, the predetermined annular portions A and B of the circular saw material 2, that is, about 0.695R to 0.
Shot peening was applied to the strip area of 761R (where R is the radius of the circular saw blank 2).
It was confirmed that good shot insertion can be performed by projecting shot particles onto the annular region in the range of 0.8R.

Further, FIGS. 4 and 5 show a second embodiment of the present invention. In this example, as shown in FIGS. 4 and 5, attachment of the circular saw blank 2 to the holding jig 3 is carried out. The previously mentioned mask plate 19
By using only a pair of ring-shaped members 17a and 17b without using a and 19b, shot grains are projected from the predetermined portion between the central portion and the outer peripheral portion of the circular saw material 2 to the inner diameter side. I have to.

Specific examples are as follows.

Example 2 (1) Material and dimensions of circular saw material 2 Same as in example 1 (2) Shot grain projection range 116 mm from the center of circular saw material 2 to the inner diameter side (3) Processing conditions Example 1 The residual stress on the surface of the circular saw blank 2 obtained in Example 2 was measured in the same manner as in No. 2, and the results shown in FIG. 7 were obtained. As is clear from the measurement results of FIG. 7, in the case of this example, a strong compressive stress is generated in the entire area on the inner diameter side from the vicinity of the boundary portion of shot grain projection, and the area on the outer diameter side is larger than that. It was confirmed that a strong tensile stress was applied to the steel and that a strong waisting process was performed.
Further, as a result of the experiment, it was confirmed that good shot insertion can be performed even when the shot grain projection area is the entire area on the inner diameter side from the portion of 0.5R to 0.8R from the center of the circular saw material 2. .

It should be noted that the waist insertion method according to the present invention is the same as the above-described specific examples 1 and 2.
However, it is possible to easily adjust the waist insertion strength by appropriately changing the processing conditions such as the shot grain projection direction, the projection speed, the projection time, and the grain size material. .

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, it is not always necessary to perform the shot peening process while rotating the circular saw material 2, and it may be reversed by 180 ° at a predetermined time interval. Alternatively, the circular saw blank 2 may be stopped and shot grains may be projected from both sides thereof.

e. Effect of the Invention As described above, according to the present invention, shot grains are projected onto the entire inner surface of the circular saw material, leaving an annular region between the central portion and the outer peripheral portion or the outer peripheral edge portion of the circular saw material. By doing so, a compressive stress is generated in the circumferential direction (tangential direction) of the shot peening (plastic working) portion, and a tensile internal force along the circumferential direction is applied to the outer peripheral portion near the outermost peripheral blade portion. Therefore, it is possible to obtain a circular saw that has a good waist insertion strength and is subjected to a good waist insertion process. Moreover, according to the method of shot grain projection according to the present invention, it is possible to obtain a uniform waist insertion strength without requiring skill as compared with the conventional hammer striking method, and it is troublesome as in the conventional roll pressing method. It is possible to efficiently perform waist insertion processing with a single operation without performing repeated operations.

Further, a conventionally known shot peening apparatus may be used as an apparatus for carrying out the present method, and therefore, it is possible to automate the waist insertion process and easily save labor.

[Brief description of drawings]

1 to 3 are for explaining a first embodiment of the present invention, and FIG. 1 is a sectional view of a shot peening apparatus for carrying out a waist insertion method according to the present invention. The drawing is a front view of a jig for holding a circular saw material, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIGS. 4 and 5 are for explaining a second embodiment of the present invention. FIG. 4 is a front view showing another example of the holding jig, and FIG. 5 is V- in FIG.
A cross-sectional view taken along line V, FIG. 6 is a graph showing the measurement results of residual stress when shot grains are projected only on a predetermined annular portion of a circular saw material, and FIG. 7 is an entire surface of a predetermined inner diameter portion of the circular saw material. Graphs showing the results of measurement of residual stress when shot grains are projected onto the surface, and FIGS. 8 and 9 are sectional views showing buckling states of a circular saw, respectively. 1 ... Shot peening device, 2 ... Circular saw material, 3 ... Holding jig, 4 ... Drive mechanism, 5 ... Shot grain projection mechanism, 6 ... Device body, 17a, 17b ... Ring-shaped member, 19a, 19b ... Mask plate, 21 ... Shot grain supply source, 22 ... Shot grain supply source, 23 ... Horn-shaped member, 24 ... Impeller, A, B ... Circular ring part of circular saw blank 2 (Shot grain projection area), C ... Outer peripheral portion of the circular saw material 2, D ... Inner peripheral portion of the circular saw material 2 (shot grain projection area).

Claims (1)

[Claims] 1. In a waist insertion method performed in a circular saw manufacturing process, an annular ring extending along the entire circumference along a predetermined position between the central portion and the outer peripheral portion of a disk-shaped circular saw material. A region, or by projecting shot grains from the predetermined portion between the central portion and the outer peripheral portion of the circular saw material to the entire region on the inner diameter side,
A compressive stress is generated in the circumferential direction of the region, and in response to this,
A method for inserting a waist into a circular saw, wherein a tensile internal force along the circumferential direction is applied to a region on the outer peripheral side of the region.