JP2004060003A - Method for producing link for endless track - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method by which endless track links provided with required properties can be inexpensively produced with a reduced number of processes. <P>SOLUTION: The method for producing endless track links comprises: a process 101 where (1) a stock consisting of non-heat treated steel having a carbon content of ≤0.50 wt.% is hot-forged to form a link stock having a link shape; and a process 102 where (2) only the roller tread section 3 of the link stock having a link shape whose temperature has reached the level equal to or above an Ac<SB>3</SB>transformation point due to the remaining heat of the hot forging or reheating is rapidly cooled and hardened, and further the roller tread section 3 is self-annealed by utilizing the remaining heat in the part 4 other than the roller tread section of the link stock having the link shape. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a link that is a component of a track belt of a construction machine such as a power shovel and a bulldozer.
[0002]
[Prior art]
As shown in FIG. 3, the link 1 is a component of the endless track belt 10 of the construction machine. Since the link is used under severe conditions, the link as a whole is required to have wear resistance, strength and toughness. Further, the roller tread surface 2 of the link, which is the contact surface with the roller (rolling wheel, not shown) of the lower traveling body of the construction machine, is particularly required to have wear resistance.
In order to satisfy these required characteristics, the link has conventionally been manufactured by a raw material and forging process and a heat treatment process shown in FIG. That is,
{Circle around (1)} A material made of medium carbon alloy steel is hot forged to form a link-shaped link material (step 201);
{Circle around (2)} The entire link material having the above-mentioned Ac ₃ transformation point is rapidly cooled and quenched by the residual heat or reheating of the hot forging (Step 202).
(3) The entire link material is tempered at a high temperature (step 203),
(4) Induction heating and quenching of the roller tread portion of the link material (Step 204),
(5) Low-temperature tempering of the roller tread portion of the link material by induction heating, or low-temperature tempering of the entire link material in a heating furnace (step 205);
It is a process.
[0003]
[Problems to be solved by the invention]
However, the conventional manufacturing method has the following problems.
(1) Since the link has a roller tread portion requiring abrasion resistance and a portion other than the roller tread portion on the shoe mounting surface side requiring strength and toughness, the entire heat treatment and roller treading are performed. Two heat treatments of the surface are required. Therefore, even if hot forging is included, the link material must be heated to a high temperature equal to or higher than the Ac ₃ transformation point three times (two times when the entire link material is quenched using the residual heat of hot forging). And consumes a lot of energy.
(2) Induction heat treatment of the roller tread surface has a high power cost.
(3) Lead time is long due to the large number of processes. In the case of a line, the production line becomes longer, and the area occupied by the factory building increases.
(4) Since the number of processes is large, the inventory of the work-in-progress is increased.
(5) Since the number of processes is large, an operator is required for each process, and labor costs are increased.
SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing method capable of manufacturing an endless track link having required characteristics at a low cost with a smaller number of steps.
[0004]
[Means for Solving the Problems]
The present invention that achieves the above object is as follows. That is,
(1) a step of hot forging a material made of non-heat treated steel having a carbon content of 0.50% by weight or less to form a link material having a link shape;
{Circle around (2)} Next, only the roller tread portion of the link material of the link shape having a temperature of not less than the Ac ₃ transformation point due to residual heat or reheating of hot forging is quenched, and the roller tread portion is quenched. The step of self-tempering the roller tread portion by using residual heat of a portion other than the roller tread portion of the link shape link material,
And a method for manufacturing a link for an endless track belt.
[0005]
In the above method for manufacturing links for endless track belts, a material made of non-tempered steel is used as the material. Therefore, heat treatment of quenching and high-temperature tempering (this is called tempering) is not applied to parts other than the roller tread surface. In both cases, the strength and toughness required for the link are secured while being left to cool after rolling.
Also, immediately after hot forging, only the roller tread of the link material is quenched, so that the roller tread is hardened and hardened. Since the roller tread quenched and hardened is self-tempered by residual heat at a portion other than the tread, the subsequent low-temperature tempering step of the roller tread is not required.
As described above, according to the method of manufacturing the link for the endless track belt of the present invention, it is possible to manufacture the link for the endless track band with a smaller number of steps than the conventional manufacturing method.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method of manufacturing a link for a track belt according to the present invention will be described with reference to FIGS. 1 and 2 to 5.
[0007]
The method of manufacturing the link for the endless track belt of the present invention, as shown in FIG.
(1) A step 101 of hot forging a material made of non-heat treated steel having a carbon content of 0.50% by weight or less into a link material having a link shape;
{Circle around (2)} Next, the temperature is higher than the Ac ₃ transformation point due to residual heat or reheating (or reheating after cooling to room temperature after hot forging) in hot forging (hot forging in step 101). Only the roller tread portion 3 of the link-shaped link material is rapidly cooled to quench the roller tread portion 3, and the roller tread is made using residual heat of the portion 4 other than the roller tread portion of the link-shaped link material. A step 102 of self-tempering the surface portion 3;
including.
[0008]
Here, the name of each part of the link 1 will be described. 2 is a roller tread, 3 is a roller tread, 4 is a part or portion other than the roller tread, 5 is a shoe mounting surface, 6 is a nut seat surface, 7 is a pin hole, 8 is a bush hole, and 9 is a shoe bolt hole. The roller tread portion 3 is a concept having a thickness, whereas the roller tread portion 2 is a concept only having no thickness, and the thickness varies depending on the size of the link. , About 5 to 20 mm.
[0009]
In step 101, a material made of non-heat treated steel having a carbon content of 0.50% by weight or less supplied at room temperature is heated to a temperature of about 1200 ° C. and forged to form a link material having a link shape.
Carbon steel having a carbon content of 0.50% by weight or less includes low carbon steel and medium carbon steel.
Here, a low carbon steel has a carbon content of less than 0.30% by weight, a medium carbon steel has a carbon content of 0.30% by weight or more and 0.50% by weight or less, and a high carbon steel has a carbon content of 0.30% by weight or less. Exceeds 0.50% by weight. The carbon steel of the present invention includes a carbon alloy steel. Carbon alloy steel refers to steel in which alloy elements are added to carbon steel as necessary.
[0010]
Conventionally, in order to obtain high strength having a strength (tensile strength) of 800 MPa (about 80 kg / mm ² ) or more, heat treatment of quenching and high-temperature tempering (this is referred to as “tempering”) is performed after hot rolling. It was necessary. In this case, hot rolling and subsequent quenching, and the material must be heated twice to a temperature equal to or higher than the Ac ₃ transformation point, consume a large amount of energy.
Therefore, in recent years, by adding a small amount of precipitation hardening element such as V, Nb, Ti, etc. to carbon steel, 800MPa (about 80 Kg / mm ² ) without being subjected to tempering and leaving to cool after hot rolling. Steels with the above high strength have been developed. This is "non-heat treated steel". To date, various types have been put to practical use.
The non-heat treated steel used in the present invention is a low carbon non-heat treated steel having a carbon content of less than 0.30 wt% or a medium carbon non-heat treated steel having a carbon content of 0.30 wt% or more and 0.50 wt% or less. The steel type to be used is selected in consideration of the strength and manufacturing cost required for the link.
[0011]
In step 102, quenching and self-tempering of the roller tread portion 3 immediately after hot forging are performed. The heat required for quenching the roller tread portion 3 is desirably the residual heat of the hot forging in the step 101. However, once the hot forging is once cooled and then reheated to a temperature equal to or higher than the Ac ₃ transformation point, It may be heat.
Immediately after hot forging or immediately after reheating, only the roller tread 3 of the link material is rapidly cooled, and only the roller tread 3 is quenched and hardened.
As a method of rapidly cooling only the roller tread portion 3 of the link material, by applying "enclosure" or the like, a cooling liquid (water, oil, water-soluble cooling liquid) is not sprayed to the portion 4 other than the roller tread portion. And the like.
[0012]
The temperature of the link material after the quenching is such that the roller tread portion 3 is lower than the low temperature tempering temperature (approximately less than 200 ° C.), and the portion 4 other than the roller tread portion is lower than the low temperature tempering temperature (approximately 200 ° C. or higher). ing.
The heat held by the portion 4 other than the roller tread portion is conducted to the roller tread portion 3, and the conducted heat causes the roller tread portion 3 to be tempered at a low temperature. In other words, the link material is tempered by the heat of the link material itself without external heating. This is called "self-tempering".
[0013]
When the process of the present invention shown in FIG. 1 is made to correspond to the conventional process shown in FIG. 2, the process 101 corresponds to the process 201, and the step “(1) quenching the roller tread portion” of the process 102 corresponds to the process 204. The step of “(2) self-tempering the roller tread with residual heat other than the roller tread” corresponds to step 205. The method of the present invention does not have the conventional hardening step 202 of the entire link material and the high-temperature tempering step 203 of the entire link material, and the conventional steps 202 and 203 can be omitted.
[0014]
【The invention's effect】
According to the endless track link manufacturing method of the present invention, since a material made of non-tempered steel is used as the material, heat treatment of quenching and high-temperature tempering (hereinafter referred to as tempering) is performed at the portion 4 other than the roller tread surface portion. ), The strength and toughness required for the link can be ensured while being left to cool after rolling.
Also, immediately after hot forging, only the roller tread portion 3 of the link material is rapidly cooled, so that the roller tread portion 3 is quenched and hardened. Since the residual heat of the portion 4 indicates that the quenched and hardened roller tread portion is self-tempered, the subsequent low-temperature tempering process of the roller tread portion 3 becomes unnecessary.
As described above, according to the method of manufacturing an endless track link of the present invention, it is possible to manufacture the endless track link in a smaller number of steps than in the conventional manufacturing method.
[Brief description of the drawings]
FIG. 1 is a flow chart of a material supply and forging step and a heat treatment step in a method of manufacturing a link for an endless track belt according to the method of the present invention.
FIG. 2 is a flowchart of a material supply and forging step and a heat treatment step in a method of manufacturing a link for an endless track belt according to a conventional method.
FIG. 3 is a perspective view of a general (including the present invention) crawler belt (crawler belt) of a construction machine.
FIG. 4 is a front view of a general (including the present invention) endless track link.
FIG. 5 is a side view of an endless track link in general (including the present invention).
[Explanation of symbols]
1 Link 2 Roller tread 3 Roller tread 4 Site other than roller tread (part)
5 Shoe mounting surface 6 Nut seat surface 7 Pin hole 8 Bush hole 9 Shoe bolt hole 10 Endless track belt

Claims (1)

(1) a step of hot forging a material made of non-heat treated steel having a carbon content of 0.50% by weight or less to form a link material having a link shape;
{Circle around (2)} Next, only the roller tread portion of the link material of the link shape having a temperature of not less than the Ac ₃ transformation point due to residual heat or reheating of hot forging is quenched, and the roller tread portion is quenched. The step of self-tempering the roller tread portion by using residual heat of a portion other than the roller tread portion of the link shape link material,
A method for manufacturing a link for an endless track belt, comprising:

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