JPH0340087B2 - - Google Patents

Description

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

b. Prior Art Generally, when a force is applied to a material, a certain amount of deformation occurs, but as the applied force is gradually increased, the amount of deformation increases accordingly. However, depending on the shape of the material and how the force is applied, when the applied force reaches a certain level, a phenomenon occurs in which the material suddenly shifts to a completely different deformation from the previous deformation, that is, a buckling phenomenon occurs.

In the case of circular saws, the buckling phenomenon described above may occur due to thermal stress. The mechanism by which this buckling phenomenon occurs is as follows.

When a circular saw is used to rotate and cut objects such as wood and wood materials (including plastics), frictional heat is generated on the outer circumference of the circular saw, but at this time, friction heat is generated on the inner circumference of the circular saw. Since no heat is generated, a relatively large temperature gradient is created between the outer and inner circumferences of the circular saw. However, due to the frictional heat generated at the outer periphery, the area near the blade of the circular saw tries to stretch at the outer periphery, but is unable to do so due to the resistance at the inner periphery, so a tensile force is applied to the inner periphery. As a reaction, compressive stress is generated in the outer circumferential portion. Therefore, the rate of expansion between the outer circumference and the inner circumference of a circular saw is greatly different, and as the outer circumference expands, compressive stress is generated on the outer circumference, and tensile stress is generated on the inner circumference. , creating a stress gradient between the outer and inner peripheries of the circular saw.

When the thermal stress becomes large and the temperature of the outer periphery of the circular saw rises to a certain temperature, what had previously been expanding and contracting in a plane suddenly undergoes a different type of deformation (for example, as shown in Figures 10 and 11). As a result, the circular saw a becomes concave like a dish or becomes wavy. If such deformation or buckling occurs, the circular saw will no longer be able to cut, causing problems in cutting operations.

Therefore, in order to prevent the occurrence of buckling due to frictional heat as described above, the circular saw material is subjected to a stiffening process. This tightening process is performed by applying plastic stretching to an appropriate annular portion of the circular saw material, which applies tensile stress in the circumferential direction at the outer periphery near the saw blade, and thermal stress during cutting. As a result, the compressive stress in the tangential direction generated on the outer periphery of the saw blade is canceled out, and buckling is effectively prevented.

By the way, this type of tightening method includes the hammering method, in which a worker hits the plate surface of the saw material with a hammer to perform plastic expansion processing, and the hammering method, in which a metal roller of the saw material is applied to each plate, and a pair of metal rollers are applied to the saw material. The roller pressing method, which performs plastic stretching by strongly clamping and pressing metal rollers, has been widely used in the past.

c. Problems to be Solved by the Invention However, the above-mentioned conventional methods for tightening the waist, such as the hammering method and the roller pressing method, have the following major problems.

First, in the case of the hammering method, it requires a great deal of intuition and skill to use a hammer to strike the saw material and apply plastic stretching to the predetermined waist insertion area.
In particular, it has been difficult to save labor and automate the manufacturing process of circular saws, since many years of experience and skill are required to achieve uniform buckling strength over the entire surface to be machined. Furthermore, even if a person is sufficiently skilled, the work efficiency is very poor and it is difficult to obtain a homogeneous product, so it is not possible to mass-produce high-quality circular saws at low cost. Next, in the case of the roller pressure method, it does not require intuition or tricks compared to the hammering method, but when applying plastic stretching to the waist insert using a metal roller, it is necessary to perform pre-processing (manufacturing of the saw material). It is easily affected by the quality of accuracy of rotary grinding, etc.), and local strength and weakness of the waist adjustment are likely to occur.
Therefore, the strength of the buckling is often uneven over the entire machined surface, but in such cases, it is necessary to apply roller pressure repeatedly, or to use the hammering method described above in combination. The reality was that they were doing so. As a result, production efficiency was extremely low, and in addition, there were major problems in that it was difficult to obtain uniform buckling strength under certain processing conditions.

The present invention has been made in view of the above-mentioned actual situation, and its purpose is to be able to perform the cutting process of a circular saw efficiently without requiring any intuition or skill, and to The purpose of the present invention is to provide a method for tightening the waist that can be automated and labor-saving.

d. Means for solving the problem In order to solve the above-mentioned problem, in the present invention,
In the tightening method performed in the manufacturing process of circular saws, after a disc-shaped circular saw material is hardened and tempered, it is tightened around the entire circumference along a predetermined location between the center and the outer periphery of the circular saw material. By cooling the annular region extending in a band shape, or the entire region on the inner diameter side from a predetermined location between the center and the outer circumference of the circular saw material, to a required temperature below the tempering temperature by high-frequency induction heating. , a compressive stress is generated in the circumferential direction of the region, thereby applying a tensile internal force along the circumferential direction to a region on the outer peripheral side of the region.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9.

FIG. 1 shows a circular saw material processing apparatus 1 used for carrying out the buckling method according to the present invention. A press device 5 having a handling mechanism 4 and a cooling oil tank 6 arranged on the side of this press device 5
, a high-frequency induction heating coil 9 to which a predetermined high-frequency current is supplied from the high-frequency transformer 7 via the support member 8, and a transfer mechanism 1 for horizontally moving the high-frequency induction heating coil 9 and the high-frequency transformer 7.
0 and a high frequency power source (not shown).

As shown in Fig. 2, a disc-shaped circular saw material 1
The upper mold 2 and lower mold 3 that hold the mold 1 have receiving members 2a and 3a facing each other, and these receiving members 2a and 3a have a central hole 2b as shown in FIGS. 2 and 3. , 3b are provided, and the receiving members 2a, 3a are provided with radially extending grooves 12a,
12b are formed respectively. Furthermore, the second
As shown in the figure, a cooling oil supply pipe 13a is formed in the fixed plate 13 of the lower mold 3, and cooling oil is supplied from a cooling oil tank (not shown) through this pipe 13a as indicated by the arrow in Fig. 2. Flowing in the direction shown, the groove portion 12
a, 12b.
On the other hand, the upper mold 2 is moved in the vertical direction by a pressure cylinder 14.

The circular saw material handling mechanism 4 also includes a mounting table 16 inserted into the center hole 15 of the lower mold 3, an elevating cylinder 17 for moving the mounting table 16 in the vertical direction, and a rotating cylinder for rotating the mounting table. It is composed of an induction motor 18 for driving.

On the other hand, the above-mentioned high frequency induction heating coil 9
As shown in FIG. 5 and FIG. 5, it is made by connecting conductive pipe-like members having hollow portions 19 in series, and includes a substantially annular coil main body 9a and a coil main body 9a extending from both ends of the coil main body 9a. A pair of lead portions 9b and 9c are respectively provided. A high-frequency current is supplied to the pair of lead portions 9b and 9c, while coil cooling water is supplied to the hollow portion 19.

Next, the operation when cutting the circular saw material 11 using the circular saw material processing apparatus 1 having such a configuration will be described.

First, a thin steel plate is punched out into a disc shape using a press machine, a center hole 11a is formed in the center and a saw blade part 11b is formed on the outermost periphery as shown in FIG. 4, and then quenched and tempered. Next, rotary grinding is performed.

By engaging the center hole 11a of the circular saw material 11 obtained in this way with the mounting table 16,
The circular saw material 11 is mounted and fixed on this mounting table 16. In this case, the mounting table 16 is placed between the upper mold 2 and the lower mold 3 and the high-frequency coil 9
Since the circular saw material 11 is placed and fixed on the mounting table 16, it is placed at a predetermined heating position.

Next, the high frequency induction heating coil 9 together with the high frequency transformer 7 is horizontally moved toward the press device 5 by the transfer mechanism 10 and inserted between the upper mold 2 and the lower mold 3. As a result, the coil main body 9a of the high-frequency induction heating coil 9 is placed concentrically with the circular saw material 11 with a slight spacing therebetween, as shown in FIGS. 4 and 5. Placed.

Under such conditions, the induction motor 18 is driven to rotate, and the circular saw material 11 is placed on the mounting table 16.
At the same time, a high frequency large current is supplied to the high frequency transformer 7 from the high frequency power supply. As a result, the high frequency dielectric heating coil 9
A high-frequency large current is applied to the circular saw material 11 as shown by the arrow in FIG.
(see figure) is uniformly heated by high-frequency induction across the width L. In this case, the high frequency power source is 30KHz to 400K depending on the thickness of the circular saw material 11.
A frequency range of Hz is selected, and the heating temperature of the annular region A is set to be lower than the tempering temperature during the tempering treatment, which is the previous step.

When the circular saw material 11 reaches the required heating temperature below the tempering temperature, the high frequency induction heating coil 9
The supply of high-frequency large current to the upper mold 2 and the lower mold 2 is cut off to end the heating process, and the high-frequency induction heating coil 9 is returned to its original position together with the high-frequency transformer 7 by the transfer mechanism 10, and the upper mold 2 and the lower mold 2 are It is placed in a position away from the mold 3. At the same time, circular saw material 11
The rotation of the circular saw blank 11 is stopped and lowered by the lifting cylinder 17, so that the circular saw blank 11 is placed in its central hole 1.
1a is placed on the receiving member 3a of the lower mold 3 in a state corresponding to the center hole 15 of the lower mold 3.

Meanwhile, in synchronization with the high-frequency induction heating coil 9 coming off from between the upper mold 2 and the lower mold 3, the upper mold 2
is lowered toward the lower mold 3 by the pressure cylinder 14, and the circular saw material 11 is moved between the molds 2 and 3 as shown in FIG.
It is held between the receiving members 2a and 3a of No.3. Immediately after this, cooling oil is supplied from the cooling oil tank 6 to the fixed plate 1.
3, and the supplied cooling oil flows through this pipe 13a as shown by the arrow in FIG.
Groove portion 12a of receiving member 2a, 3a via 3a,
12b. This cooling oil flows toward the outer periphery of the grooves 12a and 12b and comes into contact with the annular region A of the circular saw material 11 which is in a heated state, cools it, and is then discharged to the outside of the device. .
At this time, since the circular saw material 11 is held between the receiving member 2a of the upper mold 2 and the receiving member 3a of the lower mold 3, it is cooled while being prevented from being deformed. The discharged cooling oil is returned to the cooling oil tank 6 through a cooling oil outlet (not shown) and is reused. When the circular saw material 11 is completely cooled in this manner, the supply of cooling oil is stopped, and the upper mold 12 is moved back upward by the pressurizing cylinder 14.

In the circular saw material 11 obtained as described above, compressive stress (negative stress) is generated in the annular region A by high-frequency induction heating and cooling of the annular region A. Due to this reaction, a tensile internal force (positive stress) is applied to the outer peripheral side portion and the inner peripheral side portion of the annular region A. the result,
A circular saw material 11 which has been subjected to a waist cutting process is obtained.
Next, on the saw blade portion 11b of this circular saw material 11,
After the setting process, a chip blade (not shown) made of cemented carbide is attached.

Next, in order to clarify the advantages of the waist tightening method using high-frequency induction heating as described above, the following experiment was conducted.

Experimental example (1) Circular saw material (a) Material SKS5 (b) Outside 305mm (c) Plate thickness 2.0mm (2) Heating area of circular saw material An annular part 106 to 116 mm wide from the center of the circular saw material ( 3) Heating conditions (a) High-frequency induction heating coil Single-turn coil 9 as shown in Figures 4 and 5 (b) Frequency 200KHz (c) Input 5KW (d) Heating temperature 380℃ (Tempering temperature of circular saw material 400 °C) (e) Heating time 10 seconds (f) Pressing force 1.0t (g) Pressure time 10 seconds (h) Cooling oil Mineral oil (i) Cooling time 8 seconds (j) Cooling oil flow rate 80/min ( k) Temperature of cooling oil: 60°C When the residual stress in the circumferential direction on the surface of the circular saw material obtained in this experimental example was measured, the results shown in FIG. 8 were obtained. In FIG. 8, the vertical axis represents the residual stress, and the horizontal axis represents the ratio of the distance r from the center of each part to the radius R of the circular saw material.

As is clear from the measurement results shown in Figure 8, the band-shaped annular region A heated by high frequency induction (see Figure 5)
Compressive stress is generated along the circumferential direction, whereas tensile stress (tensile internal force) is generated in the circumferential direction at the outer circumferential side _H1 and inner circumferential side _H2 of the circular saw material. It was recognized that Therefore, it was confirmed that this circular saw material had a good waist cutting process.

The circular saw thus obtained has a compressive stress generated in the band-shaped annular region A by high-frequency induction heating, and a tensile internal force is applied in advance to the outer peripheral portion _H1 of the annular region A. Therefore, when cutting with a circular saw, the saw blade portion 11b to which the chip blade is attached
Even if frictional heat is generated in the outer circumferential portion H ₁ near the outer peripheral portion H 1 and compressive stress is generated therein, thermal expansion will occur without applying any tensile force to the inner diameter side portion. Therefore, a large stress gradient is not generated during cutting, and therefore, the occurrence of thermal buckling of the circular saw is effectively prevented.

In order to confirm such an effect, the circular saw material 11 obtained in this example was milled to create a saw blade portion 11.
When a cutting test was conducted after attaching a chip blade made of cemented carbide to b, no abnormal phenomenon such as thermal buckling occurred, and the durability was also compared to conventional hammering method or roll pressure method. The result was similar to that of the previous one, and good results were obtained.

In addition, as a result of various experiments, the heating area was set to 0.6R~
It was confirmed that even when the annular region was set in the range of 0.8R (R: radius of the circular saw material), it was possible to perform good waist cutting.

Further, FIGS. 6 and 7 show a second embodiment of the present invention. In this example, as shown in FIG. 6, a high-frequency induction heating coil 20 is used, which is composed of a spirally wound coil main body 20a and lead parts 20b and 20c extending from both ends of the coil main body 20a. The entire region B (see FIG. 7) on the inner diameter side from a predetermined location between the center and the outer circumference of the circular saw material 11 is cooled by high-frequency induction heating to a required temperature below the tempering temperature.

An experimental example to which this example is applied is shown below.

Experimental example (1) Circular saw material (a) Material SKS5 (b) Outside 305mm (c) Plate thickness 2.0mm (2) Heating area of circular saw material The entire area on the inner diameter side from the center of the circular saw material to 116mm ( 3) Heating conditions (a) High frequency induction heating coil Spiral coil 9 as shown in Figures 6 and 7 (b) Frequency 200KHz (c) Input 25KW (d) Heating temperature 380℃ (Tempering temperature of circular saw material 400℃ ) (e) Heating time 15 seconds (f) Press force 1.0t (g) Pressure time 15 seconds (h) Cooling oil Mineral oil (i) Cooling time 13 seconds (j) Flow rate 80/min (k) Oil temperature 60°C When the residual stress in the circumferential direction on the surface of the circular saw material obtained in this experimental example was measured, the results shown in FIG. 9 were obtained. Note that in FIG. 9, the vertical axis represents residual stress, and the horizontal axis represents r/R, as in FIG. 8.

As is clear from the measurement results shown in FIG. 9, in the case of this example, compressive stress is generated in the circumferential direction of the inner diameter side region B from near the boundary of high frequency induction heating, and the compressive stress is generated in the circumferential direction of the inner diameter side region B. It was confirmed that a tensile stress (tensile internal force) was generated along the circumferential direction, and this resulted in a strong stiffening process.

Also, in the case of the circular saw material 11 obtained in this experimental example, good results were obtained without causing thermal buckling during cutting, similar to those obtained in the previously described experimental examples.

As a result of various experiments, the heating area was set at 0.5R to 0.8R from the center of the circular saw material (R: radius of the circular saw material).
It was confirmed that even when the entire area from the part on the inner diameter side was used, good waist-cutting processing could be performed.

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

For example, the heating temperature, heating time, pressing force, pressing time, cooling time, etc. of the predetermined area A or B of the circular saw material 11 are not limited to the experimental example described above, and may be changed as necessary. (However, the heating temperature can be changed arbitrarily below the tempering temperature), and by changing these appropriately, the stiffening strength can be adjusted.

e Effects of the Invention As described above, the present invention provides a band-shaped annular region between the center and the outer periphery of a circular saw material after quenching and tempering treatment, or a region on the inner radial side of the outer periphery of the circular saw material while leaving the outer periphery. By high-frequency induction heating the entire area to a required temperature below the tempering temperature, compressive stress is generated in the circumferential direction of this area (high-frequency induction heating part), and in response to this, the area on the outer peripheral side of this area (the outermost This method applies a tensile internal force along the circumferential direction to the outer periphery of the saw blade (near the saw blade), so it is possible to perform a good stiffening process with strong stiffening strength simply by applying high-frequency induction heating to a predetermined area. You can get a circular saw. Moreover, according to the method for inserting the waist according to the present invention, it is possible to obtain a uniform strength for inserting the waist without requiring skill compared to the conventional hammering method, and it also requires the troublesome repeated operations like the conventional roll pressing method. It is possible to perform the waist tightening process efficiently in a single operation without having to carry out additional work. Therefore, it is possible to automate the waist-fitting process and save labor.

Furthermore, the heating temperature can be adjusted accurately and easily by high-frequency induction heating, and by adjusting the heating temperature and cooling conditions, the waist insertion strength can be adjusted accurately and easily.

[Brief explanation of drawings]

Fig. 1 is a front view of a circular saw material processing device used to carry out the method for tightening a circular saw material according to the present invention, Fig. 2 is an enlarged sectional view of a press device, and Fig. 3 is a view of the lower die. A plan view of the receiving member; FIG. 4 is a perspective view showing the arrangement relationship between the circular saw material and the high-frequency induction coil;
5 is a sectional view taken along the line -- in FIG. 4, FIGS. 6 and 7 show a second embodiment of the present invention, FIG. 6 is a perspective view similar to FIG. The figure is a sectional view taken along the - line in Figure 6, and Figure 8 is a graph showing the measurement results of the residual stress in the circumferential direction on the surface of the circular saw material that has been subjected to waist cutting using the high-frequency induction heating coil shown in Figure 4. Figure 9 is a graph showing the measurement results of residual stress in the circumferential direction on the surface of the circular saw material that has been subjected to waist cutting using the high-frequency induction heating coil shown in Figure 6. Figures 10 and 11 are the buckling states of the circular saw. FIG. 1...Circular saw material processing device, 2...Upper mold, 3...
...Lower mold, 2a, 3a...Receiving member, 4...Circular saw material handling mechanism, 5...Press device, 6...Cooling oil tank, 7...High frequency transformer, 9...High frequency induction heating coil, 11 ...Circular saw material, 11a...Central hole,
11b...Saw blade part, 12a, 12b...Groove part, 1
3a... Cooling oil supply pipe line, 14... Pressurizing cylinder, 16... Mounting table, 17... Elevating cylinder, 1
8... Induction motor, 20... High frequency induction heating coil, A... Band-shaped annular region of circular saw material 11, B... Entire area on the inner diameter side of circular saw material 11.

Claims (1)

[Claims] 1. In the tightening method performed in the manufacturing process of a circular saw, after a disc-shaped circular saw material is hardened and tempered, the entire circumference is tightened along a predetermined point between the center and the outer periphery of the circular saw material. The annular region extending in a band shape over the circular saw material, or the entire region on the inner diameter side from a predetermined location between the center and the outer periphery of the circular saw material, is cooled by high-frequency induction heating to a required temperature below the tempering temperature. A method for tightening a circular saw, characterized in that a compressive stress is generated in the circumferential direction of the region, thereby applying a tensile internal force along the circumferential direction to a region on the outer peripheral side of the region.