KR19990043572A - How to minimize thermal deformation of metals - Google Patents

Abstract

The present invention relates to a method for minimizing thermal deformation of a metal, comprising: a blank step of forming a predetermined metal into various shapes so as to minimize the amount of thermal deformation after heat treatment during processing of a metal requiring precision, and the blanked metal Chiseling step of removing the excess by forging in the forging, carburizing step of heat-treating or quenching by infiltrating carbon on the surface layer of the metal and curing only the surface layer, and sliding silicon carbide between the lap tool and the metal A metal working method comprising a lapping step of removing convex portions of a polished surface by using abrasion between the two surfaces to create a good flat surface, wherein the metal is disposed after the blanking step to minimize thermal deformation of the metal. Tempering step of holding the same at about 150 to 300 ° C. for about 30 to 90 minutes, and then air-cooling the same. Minimize thermal deformation of the metal, it characterized in that the further included.

Description

How to minimize thermal deformation of metals

The present invention relates to a method for minimizing thermal deformation of a metal, and more particularly, to a method for minimizing thermal deformation of a metal capable of minimizing thermal deformation after heat treatment during processing of a metal requiring precision.

In general, in order to manufacture a desired target workpiece using a metal as a blank, a blanking step is performed in which punches and dice are used to beat the metal to be formed into various shapes, and a welding or Chiseling step of removing by forging, carburizing step of heat-treating or quenching by infiltrating carbon into the surface layer of the metal, and hardening only surface layer, and putting silicon carbide mainly between the tool called lap and the metal and sliding Lapping step is used to remove convex parts of the polished surface by using the abrasion action of the liver to make a good flat surface.

On the other hand, in general, all metals have a slight difference in carburizing or heat treatment. Residual stresses remain. Conventionally, in order to minimize the amount of thermal deformation, methods such as refrigerant type, heat treatment condition, method change, material type or forging molding condition, processing condition, and shape of heat treatment jig have been used.

Among the conditions for minimizing thermal deformation, there is a method of minimizing the processing residual stress generated during processing by changing the processing conditions, but this has the disadvantage that it does not reduce the productivity of the processing and increases the processing cost and also does not remove the complete processing residual stress.

Due to these problems, thermal deformation due to residual stress remains a problem or adds a grinding process after heat treatment, and has various problems in terms of quality and cost.

Therefore, the present invention has been made to solve the conventional problems as described above, so as to minimize the heat deformation after heat treatment during processing of metals requiring precision, to reduce or eliminate secondary processing amount and achieve quality improvement after heat treatment In addition, the present invention provides a method of minimizing thermal deformation of metals, which can improve processing productivity and reduce costs by improving processing conditions.

Figure 1 shows the change in roundness of the embodiment using the method of minimizing the thermal deformation of the metal according to the present invention, Figure 2 is a graph showing the change in the roundness of the existing product.

In order to achieve the above object, the present invention provides a blanking step of forming a metal into a predetermined shape using turning or punching and a die, and a chiseling to remove excess from the blanked metal by welding or forging. (Chiselling) step, carburizing step of quenching by invading carbon in the surface layer of the metal and curing only the surface layer, and inserting silicon carbide between the lap tool and the metal and sliding to make a convex surface of the grinding finish using the wear action between the two (Iii) a lapping step of removing a portion to form a good flat surface, wherein the metal is heated to about 150 ° C. to 300 ° C. after the blank step to minimize thermal deformation of the metal. By maintaining this for about 30 minutes to 90 minutes, and further comprising a tempering step of air cooling or slow cooling to achieve the object of the present invention There.

Hereinafter, preferred embodiments of the present invention will be described in detail to the extent that a person skilled in the art may easily implement the present invention.

Here, as an embodiment of the present invention will be described focusing on the manufacturing process of the gear (Gear).

As a blanking step, a predetermined metal is processed into a predetermined gear shape by punching, dice or turning. The tempering step then reheats the gear to a temperature below the transformation point and air cools to minimize subsequent thermal strain on the gear. The next chiseling step removes the excess from the gear by applying heat and pressure to a constant temperature. In the carburizing step, carbon is infiltrated into the surface layer portion of the gear to quench and harden only the surface layer portion. Finally, as a lapping step, silicon carbide is inserted between the lapping tool and the gear and slid to remove convex portions of the polished surface by using abrasion between the two to make a good flat surface.

Here, in order to minimize the heat deformation of the gear before the chiseling step, the gear is heated to about 150 ℃ to 300 ℃, it is maintained for about 30 minutes to 90 minutes, then in various stages carried out later by air cooling or slow cooling Minimize thermal strain.

As a result of the operation of such a method will be described with reference to the specific data as follows.

Table 1 below and attached Figure 1 is a result of the inner diameter roundness of the gear applying the tempering step, Table 2 and attached Figure 2 shows the inner diameter roundness of the metal without applying the tempering step. μm)

Here, the roundness is the degree to which the gear is not a true cause. In order to check the roundness, the radius error is measured by the comparator while rotating the gear supported at both centers. Say what you got.

number Blank Tempering softening Hardening One 21.79 20.62 23.55 25.61 2 20.87 24.11 20.66 29.72 3 17.95 18.72 18.85 23.44 4 12.65 13.84 11.84 18.20 5 18.11 22.15 19.78 13.63 Average 18.27 19.89 18.94 22.12

number Blank Tempering softening Hardening One 18.74 - 21.98 28.85 2 13.46 - 12.55 53.98 3 13.10 - 10.10 40.01 4 19.37 - 18.90 49.30 5 16.34 - 16.82 37.23 Average 16.20 - 16.07 41.87

As can be seen in each table and drawing above, the gears subjected to tempering according to the present invention before the chiseling process can be seen that the roundness is reduced by about 50% compared to the conventional products. That is, when looking at the increase in roundness, the product to which the thermal deformation minimization method according to the present invention is applied is increased by 3.85 μm on the average, whereas in the case of the existing product, the thermal strain is increased by 25.67 μm.

In this case, the softening refers to an operation of heating the gear to the vicinity of the transformation point and gradually cooling it in order to make the gear flexible or increase the processability, and hardening the gear by hardening it by appropriate machining or heat treatment. Say manipulation.

As described above, although the present invention has been described with reference to the above embodiments, various modifications may be made by those skilled in the art without departing from the scope and spirit of the present invention.

Therefore, according to the method of minimizing the thermal deformation of the metal according to the present invention, by tempering the metal before entering the chiseling process, the amount of thermal deformation after heat treatment is reduced by about 50% to reduce or eliminate the secondary processing amount by heat treatment. After heat treatment, the quality can be improved and the processing conditions can be improved to improve the productivity and cost.

Claims (1)

A blank step of forming a predetermined metal into various shapes using punches, dice, and turning, a chiseling step of removing excess from the blank metal by forging, and a surface layer portion of the metal Carburizing step of heat-treating or quenching carbon to harden the surface layer, and inserting silicon carbide between the lap tool and the metal and sliding them to remove convex parts of the polished surface by abrasion action between the two. In the metal processing method consisting of a lapping step to make a, In order to minimize the heat deformation of the metal after the blank step, the metal is heated to about 150 ℃ to 300 ℃, it is maintained for about 30 minutes to 90 minutes, and then further comprises a tempering (Tempering) step of air cooling Characterized in a method for minimizing thermal deformation of metals.