KR20010069135A - Method of producing a tripod housing and a FTJ outer race for a constant velocity joint - Google Patents

Abstract

PURPOSE: A method for manufacturing tripod housing and FTJ (free ring tripod joint) outer race for an automobile constant velocity joint is provided to effectively remove a decarburized layer generated during heat treatment operation such as spheroidizing annealing, process annealing and low temperature annealing during cold forging and work hardening generated during forging process by adding carbon restoration and normalizing steps in the manufacturing process. CONSTITUTION: The method for manufacturing a tripod housing for an automobile constant velocity joint comprises performing carbon restoration and normalizing steps after carrying out cold forging step by cutting a steel product to a desirable size; and passing through shot, lubrication and sizing treatment steps. The method for manufacturing an FTJ (free ring tripod joint) outer race for an automobile constant velocity joint comprises performing carbon restoration and normalizing steps after carrying out cold forging step by cutting a steel product to a desirable size; and passing through shot, lubrication and backward extrusion steps.

Description

Method for producing a tripod housing and a FTJ outer race for a constant velocity joint}

TECHNICAL FIELD The present invention relates to the manufacture of tripod housing and FTJ outer race for constant velocity joints for automobiles. In particular, the present invention relates to spheroidizing annealing, intermediate annealing, low temperature annealing, etc. The present invention relates to a tripod housing for automobile constant velocity joints and an FTJ outer race that can effectively remove the decarburized layer generated during the heat treatment and the work hardening generated during the forging process.

In general, a constant velocity joint (Constant Velocity Joint) for automobiles is the most essential part of the front wheel drive car is installed on the drive axle connected to the longitudinal reduction gear to transmit power to the front wheels.

At present, in the global automobile market, miniaturization and light weight are pursued, and the front wheel drive vehicle, which is relatively advantageous in volume and weight, is leading. In such a front wheel drive car, the front wheel must also be driven at the same time to perform the steering function, so when using a hook joint (Hook Joint) when the steering angle is large, the rotational speed of the front wheel is severely fluctuated causing driving problems. However, if a constant velocity joint is used, even if the power is transmitted at a large angle change, there is no change in rotation speed and torque is transmitted evenly.

Conventional constant velocity joints with these functions and characteristics are FTJ free ring tripod joint outer race, inner race, drive shaft, spider assembly, tripod housing (Tripod Housing).

The manufacturing methods of Tripford housing and FTJ outer race, which are the core parts of the constant velocity joint, are mainly forging-to-cold sizing and cold forging-to-cold sizing.

However, the decarburized layer generated in the forged product during the forging operation lowers the quenchability during the high frequency heat treatment of the finished product, so that the surface hardness of the finished product is HRC45 or lower than the prescribed value HRC58 to 63. Premature wear on the product can cause serious impacts on product performance and lifespan due to malfunction and noise.

In addition, in the latter manufacturing process, due to the work hardening generated during cold forging, there is a problem that a lot of stress remains in the forging product, serious trouble occurs during processing, and workability is significantly reduced.

The present invention has been made to solve the above-mentioned conventional problems, the first object of the present invention in the manufacture of tripod housing for automobile constant velocity joints, such as spherical annealing, intermediate annealing, low temperature annealing during cold forging The present invention provides a method for manufacturing a tripod housing for an automobile constant velocity joint, which can effectively remove the decarburization layer generated during the heat treatment and the work hardening generated during the forging process.

In addition, the second object of the present invention is in the manufacture of FTJ outer race for the constant velocity joint of automobiles, during the decarburization layer and forging process generated during heat treatment operations such as spheroidizing annealing, intermediate annealing, low temperature annealing during cold forging The present invention provides a method for manufacturing an FTJ outer race for a constant velocity joint of an automobile that can effectively remove the generated work hardening.

1 is a manufacturing process diagram of a tripod housing for a vehicle constant velocity joint according to a first embodiment of the present invention, and

FIG. 2 is a manufacturing process diagram of a FTJ outer race for a constant velocity joint of a vehicle according to a second exemplary embodiment of the present invention.

In order to achieve the first object as described above, the present invention,

After the steel is cut to a desired size to perform a cold forging step, and then subjected to the coal sanding and normalizing step, and provides a manufacturing method of the tripod housing for the constant velocity joints for automobiles, characterized in that it is manufactured through a short and lubrication and sizing treatment. .

In the cold forging step, the cut steel is subjected to spheroidizing annealing, shortening and lubrication, and then extruded forward, and then subjected to shot and lubrication, upsetting, and annealing again. After the short and lubrication, the ironing process is characterized in that.

In addition, in order to achieve the second object as described above, the present invention,

After cutting the steel to the desired size, and performing a cold forging step, and then subjected to the shot coal and normalizing step, the FJ outer race for the constant velocity joint (FTJ) outer race, characterized in that it is manufactured through a short, lubrication and back extrusion step It provides a manufacturing method.

The cold forging step is characterized in that the cut steel is subjected to spheroidizing annealing, shot and lubrication, and then extruded forward, subjected to shot and lubrication and upsetting again, annealing again, subjected to shot and lubrication and back extrusion. .

In the manufacturing method of the tripod housing and the FTJ outer race as mentioned above, the step of coal briquetting and the normalizing step is to maintain the cold forged steel at 850-900 ° C. at 0.45-0.7% C%. After heating in the furnace for 1.5 to 3 hours, the product is cooled in an RX gas or nitrogen atmosphere, and the product temperature is extended to the outside of the furnace at 200 ° C. or lower, and air cooled.

Hereinafter, with reference to the accompanying drawings will be described in detail a manufacturing method of the tripod housing and FTJ outer race for the constant velocity joint of the vehicle according to the present invention.

1 is a manufacturing process diagram of a tripod housing for a vehicle constant velocity joint according to a first embodiment of the present invention.

Referring to Figure 1, the manufacturing process of the tripod housing according to the present invention, steel cutting → spherical annealing → shot → lubrication → primary forward extrusion → shot → lubrication → secondary upsetting → intermediate annealing → shot → lubrication → 3 Secondary back extrusion → low temperature annealing → shot → lubrication → 4th ironing → shot coal & normalizing → shot → lubrication → 5th sizing

FIG. 2 is a manufacturing process diagram of a FTJ outer race for a constant velocity joint of a vehicle according to a second exemplary embodiment of the present invention.

2, the manufacturing process of the FTJ outer race according to the present invention, the steel cutting → nodular annealing → shot → lubrication → primary forward extrusion → shot → lubrication → secondary upsetting → intermediate annealing → shot → lubrication → 3rd back extrusion → shot coal & normalizing → shot → lubrication → 4th sizing

As described above, the decarburized layer generated during heat treatment operations such as spheroidizing annealing, intermediate annealing, and low temperature annealing during cold forging, which is essentially involved in the manufacturing process of the tripod housing for automobile constant velocity joints and the FTJ outer race, is a finished product. HRC45 or lower value of the finished product's surface hardness is lower than HRC58 ~ 63, which is lower than the prescribed value.Therefore, premature wear occurs during assembly operation with the counterpart. This will seriously affect the performance and life of the product.

In addition, due to the work hardening generated during cold forging, a large amount of stress remains in the forging product, there is a problem that a serious trouble occurs during processing to significantly reduce the workability.

In order to solve this problem, in the present invention, the shot coal & normalization is carried out.

As is known, carbon restoration is a method of replenishing the C% lost in the decarburization portion and returning it to the same amount of carbon as the raw material. The gas restoration of the furnace is heated to charcoal at 800 to 900 ° C. At this time, it is important to adjust the amount of charcoal in the same way as the C% of the material. In general carburization, the C% of the surface layer is 0.9% regardless of the C% (0.1 to 0.2%) of the material, and the adjustment of the amount of charcoal is hardly considered. It is possible to recover the decarburized layer by the ablation method.

In addition, as known, normalizing refers to an operation of heating the steel to a temperature of about 30 to 50 ° C. higher than the A ₃ line or the A _cm line, austenitizing, and then cooling it in air. The purpose of normalizing is to remove the influence of pre-processing and refine the grains to improve mechanical properties.

In the present invention, as the complex & normalizing step, the heating temperature in the furnace is set to 850 ~ 900 ℃ according to the steel grade at 0.45 ~ 0.7% C%, and the holding time is set for 1.5 to 3 hours according to the thickness of the product After cooling in an RX gas or nitrogen atmosphere, the product is cooled to 200 ° C. or lower and cooled to air.

As described above, in the method for manufacturing a tripod housing for an automobile constant velocity joint according to the present invention, the spheroidizing and normalizing at the time of cold forging are performed by performing shot coaling and normalizing between the fourth ironing and the fifth sizing step. It is possible to effectively remove the decarburization layer generated during the heat treatment operation such as annealing and the work hardening generated during the forging process.

Similarly, in the manufacturing method of the FJ outer race for a constant velocity joint for automobiles according to the present invention, spheroidizing and normalizing during cold forging, by performing double shot and normalizing between the third back extrusion and the fourth sizing step, It is possible to effectively remove the decarburization layer generated during the heat treatment operation such as low temperature annealing and the work hardening generated during the forging process.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (6)

A method of manufacturing a tripod housing for an automobile constant velocity joint, characterized in that the steel is cut to a desired size and then subjected to a cold forging step, followed by a shot coal and normalizing step, and a shot and lubrication and sizing. The method of claim 1, wherein the cold forging step, the extruded annealing, the shot and lubricated in front of the steel after the spheroidized annealing, shot and lubrication, and then again annealing by shot and lubrication and upsetting, and again through the shot and lubrication After extrusion, annealing at a low temperature, and after the short and lubrication, ironing process for the automobile constant velocity joint, characterized in that the manufacturing method of the tripod housing. The method according to claim 2, wherein the coal and the normalizing step, after heating the cold forged steel in a furnace maintained at 850 to 900 ℃ at C5 of 0.45 to 0.7% for 1.5 to 3 hours, under RX gas or nitrogen atmosphere A method of manufacturing a tripod housing for an automobile constant velocity joint, characterized by cooling and heat-treating until the temperature of the product reaches 200 ° C. or lower, and then cooling it out of the furnace. After cutting the steel to the desired size, and performing a cold forging step, and then subjected to the shot coal and normalizing step, the FJ outer race for the constant velocity joint (FTJ) outer race, characterized in that it is manufactured through a short, lubrication and back extrusion step Manufacturing method. The method of claim 4, wherein the cold forging step, the extruded annealing, shot and lubricated the front steel after spheroidized annealing, after the shot and lubrication and upset the intermediate annealing, again through the shot and lubrication A method of manufacturing an FTJ outer race for a constant velocity joint for automobiles, characterized by extruding. The method according to claim 5, wherein the complex and the normalizing step, after heating the cold forged steel in a furnace maintained at 850 to 900 ℃ at C5 of 0.45 to 0.7% for 1.5 to 3 hours, under RX gas or nitrogen atmosphere A cooling method for manufacturing a FTJ outer race for a constant velocity joint for automobiles, characterized in that cooling is carried out to the outside of the furnace at a temperature of 200 ° C. or lower.