JPS62207827A - Method for applying residual tensile stress to circular saw for cutting metal - Google Patents

Abstract

PURPOSE:To allow internal tensile stress to remain in the specific section of a circular saw so that clattering and oscillating of the circular saw during cutting are effectively prevented by attaching rings to the sections of the prescribed radial circle on both side faces of the circular saw and subjecting the entire part to quick heating and quick cooling. CONSTITUTION:Respectively circular residual tensile stress parts 1b are held on both side faces 1a of the circular saw 1. The radius of the circular saw is designated as R and the radius of the residual tensile stress 1b as (r), then (r) is so set as to satisfy 0.65R<=r<=0.8R. Respectively the same metallic rings 2 are mounted by means of a bolt and nut 3 to both side faces 1a of the circular saw 1 in order to form said residual tensile stress 1b. The rings 2 having the larger heat capacity are more preferable and therefore, the thickness thereof is made substantially large. The diameter and width thereof are made to coincide with the diameter and width of the parts 1b. The circular saw 1 with such rings is carried into a heating furnace 4 and is uniformly heated overall to the temp. above the tempering temp. of the circular saw 1 and below the A3 transformation point thereof; thereafter, the circular saw is taken out of the furnace 4 and is quickly cooled by immersing the same into cooling water or cooling oil in a cooling tank 5.

Description

[Detailed Description of the Invention] The present invention provides a circular saw for metal cutting with vibration resistance (chattering prevention structure).
It relates to a method of applying tensile residual stress to a specific location in order to give the same.

Conventional circular saws for metal cutting can be said to be metal processing tools with low rigidity because their plate thickness is thin compared to their diameter. Therefore, when cutting is performed using this tool, chatter vibration is likely to occur due to the tool itself.

As a result, machining efficiency and machining accuracy are reduced.

There are two types of circular saws: one for cutting wood and one for cutting metal. However, circular saws for metal cutting have a shorter history than circular saws for cutting wood, and their cutting speed is about 1/20 slower. Since the conditions are significantly different, it is not possible to directly apply the vibration isolation technology of circular saws for wood cutting, and the current situation is that the vibration isolation technology has not yet been sufficiently established. Therefore, conventionally, in order to guarantee a predetermined machining accuracy, the machining speed has to be slowed down sufficiently.

Therefore, as a result of many years of research, the present inventors have discovered a method for effectively preventing chatter vibration during cutting with a circular saw for metal cutting by allowing tensile internal stress to remain in specific parts of the circular saw.

That is, when the circular saw radius is R, the present inventors rapidly heated a circular portion with a radius of approximately (0.65R to 0.8R) on both sides of the circular saw, particularly a circular portion with a radius of 0.75R, and When it is rapidly cooled and tensile internal stress remains in the rapidly heated and rapidly cooled parts,
It has been found that as the rigidity of the circular saw increases, so does the damping effect, and as a synergistic effect of the two, chatter vibrations during cutting can be extremely effectively prevented.

This is due to the following reasons.

In other words, when both sides of a circular saw are rapidly heated and cooled, and tensile internal stress remains in the predetermined areas of the rapidly heated and rapidly cooled parts, the natural frequencies of each mode of the circular saw shift, causing especially chatter vibration. The natural frequency of the dominant higher mode (2.3.4 mode) is
When the rapid heating/quenching region radius is approximately 0.6511 or more, it shifts to a larger value, thereby improving the rigidity of the circular saw. On the other hand, the larger the radius of the rapid heating/quenching part, the better.If the area near the outer peripheral cutting edge of a circular saw is rapidly heated/cooled, tensile internal stress in the radial direction is less likely to occur, so higher-order modes Shifts in natural frequencies are also less likely to occur,
In other words, the anti-chatter effect tends to decrease, and the hardness of the cutting edge also decreases. Therefore, the maximum radius of the rapid heating/quenching portion of the circular saw is approximately 0.8R. Therefore, by setting the radius of the rapid heating/quenching part in the range of approximately 0.65R to 0.8R, the rigidity of the circular saw based on the shift of the natural frequency of the higher mode can be improved and the chatter vibration of the circular saw can be reduced. can be effectively prevented. In addition, it is preferable that the rapid heating/quenching region is rapidly heated at a temperature higher than the tempering temperature and lower than the A3 transformation point temperature, and then rapidly cooled. If the rapid heating temperature is too high, the tool may be deformed or the tool may be unhardened and softened. Conversely, if the rapid heating temperature is too low, a sufficient amount of internal stress may not remain.

Moreover, when the preheating temperature is A, the transformation point temperature or higher, the vibration resistance effect is small. The reason for this is not clear, but it may be because the rapid cooling of austenite generates needle-shaped crystals, which makes it difficult for slippage to occur at the interface between the heat-treated area and other areas adjacent to it. It is speculated that there is. The optimum heating temperature is A, the highest temperature below the transformation point and at which the tool does not deform.

Also, conveniently, if both sides of the circular saw are rapidly heated and cooled in this way and tensile internal stress remains in the rapidly heated and rapidly cooled parts, the damping effect is improved at the same time, and in particular,
This damping effect becomes significant when a temperature difference occurs between the radial inside and outside of the circular saw during cutting.

By the way, in the sense of applying residual stress to a specific part of a circular saw, a solution that pressurizes the part can also be considered, but compared to this pressurizing method, this rapid heating/quenching method is more effective in the thickness direction of the circular saw. This method has the effect of allowing the tensile internal stress to remain deeply, and is an extremely effective method for achieving the purpose of vibration isolation for circular saws.

In the above configuration, it is preferable that the circles of the rapid heating/quenching region be discontinuous circles rather than continuous circles. By forming discontinuous circles in this way, the diagonal cut □ phenomenon of the circular saw is alleviated, and the tool life is also improved. If the rapid heating/quenching area is made into a continuous area, the internal and external parts in the radial direction are completely separated by this continuous area, and the continuous area forms a vibration node in chatter vibration, resulting in a tendency to promote chatter vibration. be.

Now, when applying tensile residual stress to a predetermined position on a circular saw using the rapid heating/quenching method, you can simply heat it with a gas burner or high-frequency coil, and then cool it with water or oil. be.

In this case, in the heating process, it is common to use a method in which gas burners and high-frequency coils are placed at predetermined positions on both sides of the circular saw, and a circular heating section is formed while the circular saw is rotating. It is. However, with this method,
The heating time becomes longer, which makes the work more difficult, and temperature differences tend to occur in the circumferential direction, which tends to result in uneven heating.Furthermore, there are problems in that a device for rotary heating is required.

Technical problem of the present invention Therefore, the technical problem to be solved by the present invention is to provide a novel heating/cooling method for applying residual tensile stress in a circular or discontinuous circular manner to predetermined positions on both sides of a metal cutting saw. The object of the present invention is to provide a method that can shorten heating time and achieve uniform heating, and also eliminates the need for special equipment.

In order to solve the above technical problem, in the present invention, in the first step, a ring is attached to a circular part of a predetermined radius on both sides of the circular saw, or a plurality of split rings are attached. In the second stage, the entire circular saw with a ring is rapidly heated in a heating furnace, and in the third stage, the entire circular saw with a ring is rapidly cooled in a cooling liquid. Taking advantage of the fact that the cooling rate of the circular part or the discontinuous circular part to which the ring or split ring is attached is slower than that of other parts, tensile internal stress is applied to the circular part or the discontinuous circular part. I let it remain.

According to this method, although it is necessary to attach a ring or a discontinuous ring to the circular saw, this work itself can be easily performed by tightening bolts and nuts, while the heating and cooling processes are performed using a circular saw with a ring, respectively. Since the entire saw is heated simultaneously, the work is very simple, heating is done uniformly throughout the entire saw in a short time, and special equipment is used for heating and cooling. is not necessary; an existing heating furnace, water tank, or oil tank can be used.

Moreover, this method has a unique effect that it can be performed in the tempering process after hardening in the manufacturing process of the circular saw itself.

FIG. 3 shows a circular saw l for metal cutting manufactured by a method according to an embodiment of the present invention. This circular saw 1 has circular tensile stress residual portions Ib on both side surfaces 1a thereof. Now, assuming that the circular saw radius is R1 and the radius of the circular tensile stress residual 1b is r, the radius r is set so as to satisfy the following formula 0.

The tensile stress residual portion 1b is formed by the method shown in FIG. 1.2. First, referring to FIGS. 2(1) and 2(n), two identical metal rings 2 are prepared and attached to both sides 1a of a round IT with bolts and nuts 3. Each ring 2 preferably has a large heat capacity, and therefore,
The thickness dimension is made sufficiently large. The diameter and middle dimensions of each ring are made to match the diameter and middle dimensions of the tensile stress residual portion tb to be applied to the circular saw l.

Now, as shown in FIG. 1, the circular saw with rings 2 attached to both sides thereof is carried into a heating furnace 4, where it is heated entirely and uniformly. In other words, a circular saw! and all parts of the ring 2 are heated to approximately the same temperature. This heating temperature is higher than the tempering temperature of the circular saw 1 and lower than the A3 transformation point temperature, for example, 550°C.

Next, the circular saw with a ring is taken out from the heating furnace 4 and immersed in cooling water or cooling oil in the cooling tank 5. As a result, the circular saw with a ring is rapidly cooled down.

At this time, since the ring 2 itself has a large heat capacity, the cooling rate of the circular portion of the circular saw 1 to which the ring 2 is attached is slower than that of other portions, and tensile residual stress is generated there.

Figure 4 (1) shows the internal stress of the circular saw before heating and cooling treatment.
FIG. 4 (II) shows the internal stress of the circular saw produced by the above method.

As is clear from the comparison between FIGS. 4(I) and 4(n), if the heating/cooling treatment is performed, tensile stress remains only in that portion in both the circumferential direction and the radial direction.

FIG. 5 shows another embodiment. In this embodiment, a plurality of split rings 2a are used in place of the ring 2 of the previous embodiment. That is, in this example,
The eight divided rings 2a are sequentially cut with a circular saw 1 at regular intervals.
It is attached to the side surface 1a at a predetermined radius circle using bolts and nuts.

By employing this split ring 2a, discontinuous circular tensile stress can remain on each side surface 1a of the circular saw 1.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a process diagram showing the processing steps, and FIG. Figure 3 is a side view of the circular saw manufactured by the method shown in Figure 1, and Figures 4 (1) and (II) show the stress distribution of the circular saw manufactured by the method shown in Figure 1. FIG. 5 is a side view of a circular saw with a split ring showing another embodiment. l...Circular saw for metal cutting, la...side, lb...
Tensile stress residual part, 2... ring, 2a... split ring, 3... bolt/nut, 4... heating furnace, 5...
・Cooling tank. Patent applicant: Agent of Kobe Steel, Ltd.
Patent Attorney Blue and White Two Idiots First! ! ! Figure 2 (I) Wi21! I (M) No. 3 yi Fig. 4 (I) No. 5 ig \~--1~/

Claims (1)

[Claims] 1. A method of applying tensile residual stress to a portion of a predetermined radius circle on both side surfaces of a circular saw, in the first step, a ring is attached to a portion of the circular radius circle on both side surfaces of the circular saw. or a plurality of split rings are attached discontinuously, and in the second step, the entire circular saw with a ring is rapidly heated in a heating furnace, and in the third step, the entire circular saw with a ring is rapidly cooled in a cooling liquid. A method for imparting tensile residual stress to a circular saw for metal cutting, characterized in that: