Abstract
A multi combination cold heading die for bearing rolling elements, particularly suitable for the cold heading process of large-sized steel balls and rollers. The commonly used molds currently adopt integral or two combination structures, made of GCr15 steel, with a low service life and easy damage. This design incorporates a transition ring and buffer pad with a lower material recovery coefficient between the mold core and the mold shell, thereby improving the service life of the mold and reducing production costs.
Description
A cold pier mold for bearing rolling elements, particularly suitable for the cold pier process of large-sized steel balls and rollers.
Steel balls or rollers will generate significant stress on the mold during the cold pier process, thus requiring the mold to have high strength and toughness in terms of working performance and lifespan. The mold directly affects the quality, production efficiency, and cost of the product. At present, the cold pier equipment for producing steel balls over 1 inch in China mainly includes models such as 232-52 and EPNK35. The cold pier mold generally adopts a whole or two combination structure, and the material is GCr15 steel. Currently, the mold with this structure has a low service life and is prone to damage.
The purpose of this utility model is to improve the material and structure of the above-mentioned mold structure, and design a new multi combination mold that meets the cold pier process requirements for rolling elements with a diameter of over 1 inch.
This utility model reduces the impact load on the mold shell during the cold pier process and the reaction force of the mold shell on the mold core by setting a metal buffer between the mold core and the mold shell, in order to protect the mold core from deformation and explosion and extend the service life of the mold. Reasonable selection of the wall thickness of the transition sleeve, the height of the buffer pad, as well as the selected materials and heat treatment process, can meet the cold pier process requirements of various sizes of products.
The conceptual basis of this utility model is the principle of object collision in theoretical mechanics.
Newton discovered during his study of collision laws that the ratio of the velocity at the end of a collision to the velocity at the beginning of a collision remains constant for a material determined object, i.e. | U/V |=K. In the formula, V represents the velocity before collision, U represents the velocity after collision, and K represents the material recovery coefficient.
In the process of collision, there is usually a loss of mechanical energy, which is converted into thermal energy, light energy, or other forms of energy. Therefore, the kinetic energy loss when two objects collide with each other is Δ T=T0-T1=[m1m2/(2 (m1+m2))] (1-K2) (V1-V2) 2
In the formula: T0- kinetic energy of the two objects before collision
T1- Kinetic energy of two objects after collision
V1V2- velocity of the center of mass of the two objects before collision
M1m2- Mass of two objects after collision
K - Coefficient of material recovery
The above equation indicates that the K value of the material recovery coefficient of the colliding object is an important factor affecting the loss of kinetic energy. Using this principle, a transition ring with a lower material recovery coefficient and a buffer pad are set between the mold core and the mold shell to increase the kinetic energy loss between the mold core and the mold shell, achieving the goal of reducing the impact load on the mold shell and the mold core.
Figures 1 and 2 show two embodiments of the present utility model.
Figure 1 is a schematic diagram of the three combination steel ball cold pier mold.
In the picture: 1. Mold core, 2. Mold shell, 3. Buffer pad. The interference fit or transition fit between the mold core and the mold shell, and the buffer pad require good parallelism and surface flatness.
Figure 2 is a schematic diagram of the four combination steel ball cold pier mold.
In the picture: 21. Mold core, 22. Mold shell, 23. Buffer pad, 24. Transition ring. The mold core and transition ring, the transition ring and the mold shell have interference fit or transition fit, and the cushion pad requires good parallelism and smooth surface. The transition ring and buffer pad are made of mold steel Cr12NOV or 65Nb.
This multi combination cold pier mold has the following advantages compared to commonly used integral or two combination structures:
Due to the combination of molds, the size and thickness of individual parts are relatively reduced compared to integral molds, making it easier to meet the requirements of heat treatment processes, thereby solving the problem of poor hardenability in the heat treatment process of original structural molds.
The mold material breaks the tradition of using only GCr15 bearing steel, and the buffer pad and transition ring are made of general mold steel, expanding the material range of cold pier molds.
Due to the reasonable design, the service life of the mold has been extended. After production verification, the efficiency has been tripled and the cost has been reduced by half.
Figure 1
Figure 2
2024 October 3rd Week WBM Product Recommendation:
Super finishing roll:
We have 30 years in designing and producing experience in bearings rolling elements and tooling industry with ISO9001 and IATF16949.Tooling for cold heading machine,lathe,grinder will be produced accoriding to your requirement.
