JPH0253147B2 - - Google Patents

Description

[Detailed description of the invention]

a. Field of Industrial Application The present invention relates to a method of manufacturing an integrally cast vehicle axle case. b. Conventional technology and its problems In general, the axle case 51 shown in Fig. 5 is important as a vehicle component and is attached to various parts with different functions, so different parts of the case are required to have different strength, toughness, or wear resistance. ing. For this reason, the conventional axle case 51 has a welded steel plate structure, and the case body 52 is exposed on the road surface and is hit by flying stones or rubbed by rocks while driving.
has toughness. In addition, the case body 52
The brake flange 53 and end tube 54, which are integrally fixed to both ends by welding, are equipped with parts such as tires and brake shoes via the brake drum and hub. It gives it strength. Further, leaf springs are mounted on spring stoppers 55 and 56, which are fixed to the outer peripheral surface of the case body 52 by welding or bolting, and upper and lower torque rod brackets 57 and 58 each have one end of the upper and lower torque rods. It is attached to the vehicle body frame or trunnion via upper and lower torque rods, and because it moves in contact with earth and sand and supports the weight of the vehicle, it is made of steel to provide wear resistance and strength. However, the axle case 51 with such a structure
The disadvantage was that manufacturing costs were high because a large number of parts had to be fixed together by welding, etc., and many complicated steps had to be taken to assemble them. Moreover, since it is a welded steel part, it increases its weight, leading to problems such as increased fuel consumption when the vehicle is running. Therefore, an axle case 51 that is integrally cast has recently been provided. This axle case 51 is partially hardened to provide different properties depending on the location where it is used, so as to maintain the required strength or toughness. Conventional methods of partial hardening include, for example, induction hardening after casting, flame hardening by heating with a burner, using a chilled metal, or applying stabilizers such as cementite or pearlite to the inner surface of the mold. c. Problems to be Solved by the Invention However, the above-mentioned conventional component joining method has problems such as complicated processes, increased cost, and increased weight. Furthermore, the partial curing method has the following problems. In other words, induction hardening and flame hardening methods increase the number of steps,
In particular, the induction hardening method requires large equipment, which is economically disadvantageous. Further, in frame hardening, the hardened portions become unstable, and the vehicle axle case 51 has a problem in that the reliability of the product may be poor. On the other hand, chilled metal tends to be too cold to precipitate only pearlite, and has the disadvantage that it cannot be used for parts with complex shapes. In addition, the method of applying a stabilizer may cause cementite to be formed in a narrow area, resulting in parts becoming brittle and unstable, and is not suitable for vehicle axle cases where safety is required. The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems and provide a method for producing lightweight and inexpensive castings through simple steps. d Means for Solving the Problems In order to solve the problems of the prior art described above, the present invention provides a case body in which an opening for inserting a differential gear is formed, and a case body arranged at both ends of the case body. In the method for manufacturing an axle case for a vehicle, the axle case includes a brake flange and an end tube, and a spring stopper and a vertical torque rod bracket that protrude from the outer peripheral surface of the case body. Using a mold for casting, molten spheroidal graphite cast iron is poured into the mold and solidified.
After a predetermined period of time, the mold corresponding to the brake flange and end tube is removed to expose the brake flange and end tube to the outside to give them toughness, and the spring stopper and upper and lower torque rods are removing the mold corresponding to the bracket portion to expose the spring stopper and the upper and lower torque rod brackets to the outside to impart wear resistance and high strength;
The axle case is manufactured by sequentially performing a step of exposing the case body to the outside and imparting toughness by removing a mold corresponding to a portion of the case body. Hereinafter, the present invention will be explained in detail based on illustrated embodiments. 1 to 3 show a vehicle axle case manufactured by the manufacturing method of the present invention.
This axle case 1 includes a case body 3 in which an opening 2 into which a differential gear is inserted is formed, a brake flange 4 and an end tube 5 disposed at both ends of the case body 3, and an outer peripheral surface of the case body 3. It is constructed by integrally casting upper and lower spring stoppers 6, 7 and upper and lower torque rod brackets 8, 9 that protrude from each other. The material used for the axle case 1 is spheroidal graphite cast iron, which has strength and toughness that can sufficiently replace forged steel and can be used to cast thin-walled castings with complex shapes. Spheroidal graphite cast iron differs from steel because of its chemical composition, and by adjusting the cooling rate it can be given a wide range of properties, from hard and brittle cementite to soft and sticky ferrite. The case body 3 has toughness and is designed to withstand external impact. Further, the brake flange 4 is formed between the case body 3 and the end tube 5, has higher strength than the case body 3, and is configured to securely attach parts such as a brake shoe. . Furthermore, the end tube 5 has strong toughness,
It is designed to be able to sufficiently hold tires 10 and the like. On the other hand, both the upper spring stopper 6 formed on the top surface of both sides of the case body 3 and the lower spring stopper 7 formed on the side surface of both sides have higher wear resistance than other parts of the axle case 1. The upper spring stopper 6 is configured to prevent upward movement of the leaf spring 11 that moves up and down, and the lower spring stopper 7 is configured to support the leaf spring 11 and prevent it from moving downward. ing. Further, the upper and lower torque rod brackets 8 and 9 have higher strength than other parts of the axle case 1, and are designed to support the weight of the vehicle. Therefore, one end of the upper torque rod bracket 8 formed on the central upper surface of the case body 3 is connected to the vehicle body frame 12.
The other end of the upper torque rod 13 attached to the trunnion 14 is attached to the lower torque rod bracket 9 formed on both lower surfaces of the case body 3, and the other end of the lower torque rod 15 attached to the trunnion 14 is attached at one end. It is configured. In addition,
16 is a trunnion shaft. The method for manufacturing the axle case 1 is as follows. First, molten spheroidal graphite cast iron is poured into a mold for integrally casting the axle case 1 by conventional means, and is solidified. After a predetermined period of time has elapsed, the mold corresponding to the brake flange 4 and end tube 5 is first destroyed or removed by an appropriate method, thereby exposing the brake flange 4 and end tube 5 to the outside. Then, compressed air is blown onto these brake flange 4 and end tube 5 to rapidly cool them, thereby hardening them faster than other parts and imparting toughness to them. Next, the molds corresponding to the spring stoppers 6, 7 and the upper and lower torque rod brackets 8, 9 are removed in the same manner as described above, thereby exposing the spring stoppers 6, 7 and the torque rod brackets 8, 9 to the outside. It is exposed and cooled to harden, giving it wear resistance and high strength. Finally, the mold corresponding to the case body 3 is removed in the same manner as described above to expose the case body 3 to the outside, and left in the atmosphere to harden and impart toughness. By performing each step in this order, an integrally cast axle case 1 having partially different properties can be obtained. When each part of the axle case 1 cast by this manufacturing method is measured using a hardness tester, the hardness of the case body is about 152 to 170H _B , and the hardness of the end tube 5 is about 248 to 277H _B. It was hot. In addition, when the fatigue strength of the axle case 1 of this example and the conventional product were measured using a fatigue tester, the first
The results shown in the table were obtained.

[Table] However, the numerical value is an index when the conventional product is set as 100. In other words, the axle case 1 of this example is a brake flange of the FCD-70 class (H _B 229 to 302) with high hardness and high fatigue strength. 4. End tube 5 and upper and lower torque rod brackets 8, 9, a soft and shock-resistant FCD-40 class (H _B 201 or less) case body 3, and wear-resistant spring stoppers 6, 7. Therefore, it can be determined that the axle case 1 can function satisfactorily. Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above, and various modifications and changes can be made based on the technical idea of the present invention. For example, in the embodiment described above, the end tube 5 was cooled by blowing compressed air.
More rapid cooling may be achieved by spraying with atomized water. The cooling rate can be freely changed as shown in FIG. 4, and even if the end tubes 5 of the axle case 1 are cast from the same spheroidal graphite cast iron, the hardness differs as shown in Table 2. Note that in FIG. 4, point A indicates the point at which the axle case 1 is taken out and exposed from the mold.

[Table] e Effects of the Invention As described above, the method for manufacturing a vehicle axle case according to the present invention integrates the case body, brake flange, end tube, spring stopper, and upper and lower torque rod brackets that constitute the axle case. Since it is cast and simultaneously and reliably imparts the necessary strength, toughness, or wear resistance to each part, the manufacturing process is simpler than various products made by welding parts such as steel or conventional part hardening methods. This makes it possible to manufacture highly reliable axle cases at low cost. Additionally, since the vehicle axle case manufactured by the manufacturing method of the present invention is lighter than conventional products made of welded steel parts, it can reduce combustion consumption while the vehicle is running, making it extremely economically advantageous. be.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the method for manufacturing a vehicle axle case according to the present invention.
The figure is a perspective view of the vehicle axle case, Figure 2 is a front view of the axle case attached to the vehicle body frame, Figure 3 is a side view of Figure 2, and Figure 4 is a side view of the vehicle axle case.
The figures are characteristic diagrams showing the cooling speed of a vehicle axle case by various cooling methods, and FIG. 5 is a perspective view showing a vehicle axle case manufactured by a conventional manufacturing method. 1... Vehicle axle case, 2... Opening,
3...Case body, 4...Brake flange, 5
...End tube, 6...Stopper for upper spring, 7...Stopper for lower spring, 8...
...Bracket for upper torque rod, 9...Bracket for lower torque rod.

Claims (1)

[Claims] 1. A case body in which an opening for inserting a differential gear is formed, a brake flange and an end tube disposed at both ends of the case body, a spring stopper and a spring stopper protruding from the outer peripheral surface of the case body. A method for manufacturing a vehicle axle case comprising upper and lower torque rod brackets, in which a mold for integrally casting the axle case is used, and molten spheroidal graphite cast iron is poured into the mold and solidified. and, after a predetermined period of time, removing the mold corresponding to the brake flange and end tube to expose the brake flange and end tube to the outside to give them toughness, and removing the spring stopper and upper and lower parts. a step of exposing the spring stopper and the upper and lower torque rod brackets to the outside to provide them with wear resistance and high strength by removing a mold corresponding to the portion of the torque rod bracket; and a mold corresponding to the case body portion. A method for manufacturing an axle case for a vehicle, characterized in that the axle case is manufactured by sequentially performing a step of exposing the case body to the outside and imparting toughness by removing the case body.