JPS6082647A - Clad steel plate for disc saw - Google Patents

Abstract

PURPOSE:To prepare the titled steel plate having superior cutting quality, toughness and abrasion resistance by constituting the core material of medium carbon steel, and constituting the shell material of high-carbon steel or high-carbon alloy steel. CONSTITUTION:A disc saw to be used for mowing grass or woodworking is made of a three-layered clad steel plate having a core material and a shell material on both sides of the core material. In this case, middle carbon steel contg. 0.20-0.30% carbon is used for the core material aiming mainly at high toughness, and high-carbon steel contg. >0.50% carbon, or high-carbon alloy steel contg. at least one among 2.5% Ni, <=0.7% Cr, and <0.30% Mo in said high-carbon steel is used for the shell material on both sides of the core material. Further, the thickness of the core material is made to 30-70% of the whole thickness of the three-layered clad steel plate. Thus, clad steel plate having superior characteristics for disc saw comprising a core consisting of middle-carbon steel having high toughness and shells having high hardness and superior cutting quality is obtd.

Description

[Detailed Description of the Invention] The present invention relates to a clad steel plate for a high-speed rotary blade used for mowing grass, woodworking, etc., that is, a circular saw, which has particularly excellent toughness, good cutting ability, and good wear resistance. The present invention provides a layered clad steel sheet.

Generally, cutlery is made of high carbon steel containing 0.5% by weight or more of C, and is usually hardened to obtain a predetermined hardness and ensure sharpness. However, since the material of the hardened ox is extremely brittle, the blade tends to warp and the plate breaks, making it impractical. The reality is that tempering is performed after quenching, even though the hardness and sharpness decrease to some extent.

In particular, with circular saws for mowing grass and circular saws for woodworking, which require high-speed rotation, if the blade goes off or the plate breaks during cutting, it poses a great danger to the operator, so the toughness after quenching and tempering is improved. For this purpose, Ni is usually added in a range of 25% by weight or less, but it is difficult to achieve both sharpness (hardness) and toughness even in such materials, so it is difficult to achieve both sharpness (hardness) and toughness. There was a strong demand for the development of a new rotary blade material that could be used.

Therefore, recently, clad steel plates, which have mild steel (hereinafter referred to as core material) in the center of the plate thickness and high carbon steel (hereinafter referred to as coating materials) on the front and back sides, have been attracting attention as materials for rotary blades, and have been put into practical use in some cases. ing. In this clad steel plate, high toughness is ensured by the mild steel core material, so less tempering is required compared to conventional circular sawn material made of a single high carbon steel material, and the high carbon steel of the core material requires less tempering. Since the hardness of the part is ensured, the cutting quality is also excellent, and therefore toughness and cutting quality can be satisfied at the same time.

However, as described above, the rotary blade made of a rad steel plate has the disadvantage that it is more easily worn than a rotary blade made of a single material having the same hardness.

This invention was made in view of the above circumstances, and aims to provide a clad steel plate for circular saws that improves the conventional clad steel plate for circular saws and has not only sharpness and toughness but also wear resistance. This is the purpose.

In order to achieve the above-mentioned object, the present inventors first observed the state of wear of the cutting edge of a rotary blade made of a conventional material after long-term use, and found the following fact. In other words, in the case of a conventional rotary blade made of a single material, as shown in Fig. 1 (
4) As shown in Figure 1 (B), the cutting edge part 1 gradually wears out as a whole, whereas in the case of a rotary blade made of Taranod steel plate, the core material 2 made of mild steel preferentially wears out, as shown in Figure 1 (B). It has been found that the coating material 3 made of high carbon steel wears out accordingly. From this, the core material selectively wears rapidly at the cutting edge of the cladding material, and as a result, the relative pressure on the coating material increases, and as a result, the wear of the coating material follows the wear of the core material and rapidly. It is thought that the overall wear rate of the cladding material cutting edge becomes faster than that of the single-piece cutting edge. Therefore, in order to reduce the wear on the cutting edge of the cladding material, it is necessary to suppress the wear on the core material, and for this purpose, it is necessary to increase the hardness of the core material. However, if the hardness of the core material is too high and fX is too high, the toughness will deteriorate and the properties as a clad steel will be lost. Therefore, as a result of further experiments and studies regarding the material of the core material, the inventor decided to make the material of the core material a medium carbon steel with a specific C content range, and to combine the core material with high carbon steel or high carbon steel. It was discovered that a clad steel plate for circular saws that has both sharpness, toughness, and wear resistance can be obtained by adjusting the ratio of the coating material made of alloy steel to the coating material within an appropriate range, and thus came up with this invention. Ta.

That is, the clad steel plate for circular saws of this invention has a C of 0.5.
0% (Weight q6: All components below are by weight) 1″
High carbon steel or C containing 050 or more (L%)
% or more and contains one or more of the following: Ni 2.5% or less, CrO 70% or less, Mo 0.30% or more as a coating material, and the coating material is on the back side of the core material A. In the clad steel plate for circular saws, the core material has a C of 0.
It is characterized by being a medium carbon steel containing 20 to 030 carbon, and having a core thickness of 130 to 70% of the total thickness of the steel plate.

The clad steel plate for circular saws of the present invention will be explained in more detail below.

The coating material in the clad steel plate of this invention contains 0 C.
．． High carbon steel containing 501 or more, or also 0 C
．． 501 or more, Ni 2.5% or less, Cr 0.
A high carbon low alloy steel containing one or more of 70% or less and Mo 0.30% or less is used. Here, the clothing material is C0
, 501 or more is used because if the carbon content is less than 0.50%, the hardness due to quenching and tempering will be low and the cutting ability will be insufficient, making it unsuitable for use as a cutlery. Also Ni, C
r and Co are sometimes added to improve the hardenability and wear resistance of the coating material itself, and to provide toughness after tempering, but clad steel originally has good toughness due to the core material.
Ni
The content was limited to 2.5% or less, Cr 0.70% or less, and Mo 0.30% or less.

On the other hand, medium carbon steel with a C content in the range of 02 to 03 is used as the core material. By setting the C content within this range, it is possible to obtain a core material with a thickness of 1 m while having both tV wear resistance and toughness. In other words, as shown in FIG. 3 of Examples described below, if the C content is less than 0.2φ, the amount of wear becomes extremely large, while if the C content exceeds 0.3%, the toughness decreases rapidly. In order to achieve both wear resistance and toughness, C must be within the range of 0.2 to 0.3%.

Further, in the clad steel plate of the present invention, the ratio of the core thickness to the total thickness must be 30 to 70 inches. In other words, the thickness of each coating material arranged on the front and back surfaces of the core material in the center (the thickness of the coating material on one side) needs to be 15 to 35% of the total thickness of the steel plate. The reason for this decision is as follows. In other words, the thinner the coating material, the easier it is to work with the blade.
If the coating material is thin, the proportion of the core material will inevitably be high, making it more likely to wear out, and the knife itself will become stiff, causing problems such as bending during operation. On the other hand, if the coating material is too thick, the core material ratio will be small and the toughness will deteriorate, making it more likely to break. According to experiments conducted by the present inventors, as shown in FIG. 4 of Examples described later, when the core material ratio exceeds 70 threads, the amount of wear increases, while when the core material ratio becomes smaller than 30 threads, the toughness decreases. was found to decrease rapidly. Therefore, in order to have both wear resistance and toughness, the core material ratio must be within the range of 30 to 70 inches.

When the clad steel plate of this invention is actually applied to a circular saw, it goes without saying that it is quenched and tempered, and by applying the specified quenching and tempering, it can achieve the desired sharpness (hardness),
Toughness and wear resistance can be ensured.

Examples of the present invention will be described below along with comparative examples.

SK4 steel as coating material, specifically C0.95chi, Si
O, 21%, Mn 0.42%, Po, 018%, 8
EXAMPLE 1 Three-layer clad steel plates shown in sample symbols A to K in Table 1 were prepared using 0.0007% high carbon steel and varying the core material composition and cladding ratio. Each clad steel plate was quenched and tempered to create a rotary blade with coating hardness of Hv580-680, and the impact characteristics of each rotary blade at 20°C were investigated.
The wear of the cutting edge was examined when the blade was rotated for 50 hours at 2000 rpm using a wear test equipment. However, as shown in FIG.
I looked it up.

Table 1 Among these measurement results, Table 3 shows the relationship between the C content of the core material and the impact value and wear amount for samples A to G whose core material ratio is almost constant at 33 to 39 inches. It is a diagram. Third
From the figure, it is clear that excellent wear resistance and good impact properties can be obtained when the C content of the core material is within the range of 0.2 to 0.03 cm.

Also, among the above measurement results, the C content of the core material was 0.25
FIG. 4 shows the relationship between the core material ratio, impact value, and amount of wear for samples E and HK. From FIG. 4, it is clear that good wear resistance and excellent impact properties can be obtained when the core material ratio is between 30 and 70.

As described above, according to the clad steel plate of the present invention, cutting quality is ensured by the high carbon steel or high carbon alloy steel, and at the same time, the core material is C0.2 to C0. : By using medium carbon steel with a core material ratio of 30 to 70%, it is possible to obtain good toughness and excellent wear resistance at the same time. It is ideal for circular saws with

[Brief explanation of drawings]

Figures 1 (4) and (B) are cross-sectional views showing the state of cutting edge wear in high-speed rotating blades made of conventional materials, Figure 2 is a front view of the high-speed rotating blade to show the definition of the amount of blade wear, and Figure 3 The figure is a correlation diagram showing the relationship between the C content, impact value, and wear amount of the core material of a high-speed rotating blade using a three-layer clad steel plate. Figure 4 is a correlation diagram showing the relationship between the core material ratio, impact value, and wear amount of the same high-speed rotating blade. It is a correlation diagram showing the relationship with quantity. 2: Core material, 3: Clothing material, p: Amount of wear on the cutting edge. Applicant Kawasaki Steel Co., Ltd. Agent Patent attorney Takehito Toyota (and 1 other person) Figure 1 (A) (B) Figure 2 Figure 3 Figure 4 Oto 20 30 40 50 eD 70 80
90 to. Shaft material t+Z*(%)

Claims (1)

[Claims] High carbon steel containing 0.50% or more of C by weight, or high carbon steel containing 0.50% or more of C by weight and Ni on both the front and back sides of the core material.
A circular saw equipped with a coating made of high carbon alloy steel containing one or more selected from the group consisting of 2.5% by weight or less, CrO, 70% by weight or less, and Mo 0.30% by weight or less. In the clad steel plate for use, the core material has a carbon content of 0.20-
A clad steel plate for a circular saw, characterized in that it is a medium carbon steel containing 0.30% more by weight, and the core thickness is within the range of 30 to 70% of the total thickness of the steel plate.