JPS6215608B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The disclosed technology belongs to a technology that prevents the occurrence of distortion in stationary one-sided induction hardening of steel materials by accompanied by heating on the other side.

The present invention relates to a method for stationary heating and quenching of steel materials, in which one side of the steel material is fixedly brought into contact with a heating element, heated, and then cooled. This relates to a stationary heating and quenching method for steel materials, in which quenching distortion is eliminated by applying a heating action to the other side of the element so that the balance of thermal stress becomes zero in conjunction with the attachment heating and cooling of the element. .

As is well known, surface hardening techniques such as induction hardening are widely used to harden one side of a bar or flat plate made of steel such as carbon steel in a stationary manner.

For example, in the stationary induction hardening method as illustrated in FIG. The press bars 5, 5 are brought into contact with each other using an air cylinder (not shown) to press and tighten the surface contact as shown by the arrow, and when a high frequency current is oscillated and applied from a predetermined high frequency power source 6, the high frequency inductor 3 becomes an insulator. A heating high-frequency wave is oscillated through the workpiece 7, and heating and hardening is performed in a predetermined manner over the entire area of the lower surface 4 of the workpiece 3 that is in contact with the inductor 2.

After quenching, the quenched surface 4 is cooled by cooling air from a cooling jacket 8 built into the inductor 2, thereby hardening the surface.

However, in the stationary single-sided hardening method including induction hardening, heating hardening and subsequent cooling are applied only to the single side 4 side of the steel workpiece 3 as described above, so that it is difficult to achieve a predetermined hardness. However, due to the biased thermal stress on one side of the workpiece, the workpiece 3 after quenching was greatly curved, and had the disadvantage of taking a convex shape on the inductor 3 side in the length direction.

Therefore, in order to deal with this problem, a large number of man-hours are required to remove the distortion after quenching, which is very cumbersome, and there is also the disadvantage that product precision cannot be guaranteed and costs are high.

The purpose of the present invention is to solve the problems of the stationary single-sided hardening method based on the above-mentioned conventional technology, and apply pressure to one side of a steel workpiece by contacting it with a heating element for hardening in the same way as in the past, heating and hardening it to a predetermined temperature, and cooling it. In order to minimize the balance of thermal stress due to heat input from the quenched surface, heating is also performed from the opposite side of the quenched surface, and while achieving the set hardness and quenching depth, there is no thermal strain on the entire workpiece. It is an object of the present invention to provide an excellent stationary heating quenching method for steel materials that can suppress the occurrence of .

Next, a second embodiment of the present invention that meets the above objectives will be described.
The explanation will be as follows according to the figures. Note that the same parts as in the embodiment shown in FIG. 1 will be described using the same reference numerals.

Reference numeral 9 denotes a stationary heating hardening device used directly in the method of the present invention, which is of the induction hardening type as described above, and a well-known high frequency inductor 2 installed on a base 1 has an insulator 7, and is heated as appropriate. A cooling jacket 8 is installed inside and connected to a high frequency power source 6.

Reference numeral 3 is a workpiece, which is a rack bar made of carbon steel material, and the machined tooth surface 4 thereof is placed in contact with the upper surface of the high frequency inductor 2 and set.

Press bars 5, 5 are connected to an air cylinder (not shown), and are configured to press the work 3 and firmly attach it to the upper surface of the high frequency inductor 2.

A bracket 10 is fixed to each of the press bars 5, 5 so as to face each other, and a screw nut 1 is attached to the bracket 10.
1 is installed inside, and screws 12 are inserted and screwed into each.

The screws 12, 12 are attached to the upper surface of another high-frequency inductor 13 connected to the high-frequency power source 6', and the screws 12, 12 are raised and lowered by adjusting the screw nuts 11, 11 by synchronous rotation. The child 13 is disposed opposite to the upper surface 14 of the workpiece 3 so that the child 13 can approach and move away from the upper surface 14 of the workpiece 3 at a relative distance.

In the stationary heating hardening apparatus 9 as described above, the press bars 5, 5 are raised to a sufficient height, the workpiece of the rack bar 3 is placed on the inductor 2, and then an air cylinder (not shown) is placed. is operated to lower the press bars 5, 5, and press the workpiece 3 to the inductor 2 as described above.

According to theory and experimental data, the screw nuts 11, 11 are rotated to fix the inductor 13 to the upper surface 14 of the pressing work 3 via the screws 12, 12 at a set distance.

Incidentally, if the set distance is not optimized, that is, if the inductor 13 is set too high, the workpiece 3 will be distorted downward in a convex shape, and if it is set too low, it will be distorted in a concave shape.

Therefore, based on the data, it is determined in advance so that the stress balance between the heat input from the inductor 2 and the heat input from the inductor 13 is zero.

Therefore, from the high frequency power source 6, 6' to the inductor 2, 1
A high frequency current is applied to the inductor 3 to heat it, and the entire area in contact with the inductor 2 on one side 4 of the set work 3 is heated and hardened.

During this time, the heating radiation from the upper inductor 13 enters the work 3 from the upper surface 14 of the work 3 and heats it, thereby reducing distortion due to thermal stress imbalance.
Or make it close to zero.

Therefore, no latent strain is formed on the workpiece 3 pressed between the press bars 5, 5 and the inductor 2.

After the hardening is completed, one side 4 is cooled through the cooling jacket 8. In that case, the upper inductor 13
The heating is gradually reduced to avoid imbalance of thermal stress caused by cooling.

After quenching is completed in this way, press bars 5, 5
Raise the workpiece 3, remove the workpiece 3, and replace it with the next workpiece 3.

Even after entering the curing period, the workpiece 3 does not have any latent strain as described above, so it does not bend or exhibit any substantial strain.

According to an experimental example based on the above example, in single-sided stationary induction hardening of a steel rack bar with a diameter of 27 mm and a total length of 600 mm, the same workpiece as the conventional method, the warping strain mm in the longitudinal direction was lower than that of the conventional method at a hardening range of 240 mm. 1.5
mm, but in this invention it was only 0.1 mm.
Very little data was obtained.

It is clear that the embodiments of the present invention are not limited to the above-mentioned embodiments. For example, as for the surface hardening and hardening means, it is possible to adopt appropriate means other than induction hardening, and the upper stage heating means, elevating and lowering Various modes are possible for the means, and it is also possible to control the amount of heating instead of raising and lowering.

As described above, according to the present invention, in the stationary single-sided hardening method for steel materials, one side of the workpiece is pressed against a heating element to be heated and hardened, and then cooled, while the opposite side of the hardened side is heated and hardened. By applying a heating action to the surface so that the balance of stress due to heat input does not collapse from both sides, the distortion of thermal stress due to heating and cooling of one quenched side appears to be biased from that side. Moreover, the degree of hardening and quenching depth can be obtained as set.Therefore, simply quenching eliminates the need for multiple correction steps such as subsequent distortion correction, which has the advantage of reducing man-hours and costs. Not only is this effective, but it also has an excellent effect on improving accuracy.

In addition, the device is easy to operate as it only requires processes such as approaching and separating the heating element from one side to the other and controlling the amount of heat.For example, the amount of heat input can be adjusted and set based on data obtained in advance. This has the advantage that control is not particularly complicated.

Therefore, if used in an induction hardening method, the hardening cycle can be shortened, and there is also the secondary advantage that there is no adverse effect on other lines.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of stationary heating quenching of steel materials based on the prior art, and FIG. 2 is a schematic explanatory diagram of one embodiment of the present invention. 3... Steel material, 2... Heating element, 4... Single side, 1
4...The other side.

Claims (1)

[Claims] 1. In a method of quenching by attaching one side of a steel material to a heating element in a fixed manner and applying heating and cooling, one side of the steel material is fixedly attached to the heating element to provide heating and cooling effects, and the A method for stationary heating and quenching of steel materials, characterized in that quenching distortion of the steel material is eliminated as much as possible by applying a heating action to balance the stress caused by heating on one side with respect to the opposite side. .