For a long time, our company has adopted a single station horizontal cold heading process for tapered roller blanks, which is characterized by high efficiency and automation. However, due to only one upsetting process of the metal, the material deformation is rapid, resulting in low mold life. This requires that the life of the mold be fully considered when designing the mold.
The upsetting and forming of rollers on a single click automatic upsetting machine can be completed through five steps: feeding, sectioning, inserting a concave mold, forming, and pushing out a concave mold. Among the tools used for the complete set of cold upsetting tapered rollers, the main factor that affects the stamping quality is the concave mold, which is a static part that presses the blank into the mold. During the stamping process, it is subject to great pressure and is prone to wear, settlement, or cracking. In order to improve the service life of the mold, reduce tool costs, and improve economic efficiency, the structure of the tapered roller concave mold cavity adopts a combined structure.
In the 1980s and 1990s, the six-body combined mold structure that our company researched and promoted for use mainly consists of six parts (Figure 1). This combined model cavity structure has the following characteristics: (1) The transition sleeve 2 and the work sleeve 3 are fitted with a reverse taper, and the outer sleeve 1 and the transition sleeve 2 are also fitted with a reverse taper. There is a large amount of interference, which can generate a large amount of prestress. This prestress can offset a portion of the impact pressure during stamping, thereby improving the bearing capacity of the mold and preventing the work sleeve from cracking. (2) Considering that the material deformation and friction force at the connection between the chamfer and the conical surface of the concave mold cavity are too large, which can easily lead to stress concentration, the parting surface is selected at the connection between the chamfer and the conical surface. The structure of this concave mold cavity basically guarantees the life of the mold.
Figure 1 Combined mold
As the requirements for roller stamping quality become higher and higher, a problem has become increasingly prominent in production. That is, when assembling a six-body combined mold, due to the imperfect structure of the original mold and the poor assembly guidance between the base 5 and the outer sleeve 1, assembly errors occur during the assembly of the work sleeve 3 and the bottom mold 4. After tightening the screw pad 6, it often causes a deviation between the center of the bottom mold and the center of the work sleeve (Figure 2). After stamping, the roller has a small chamfer and a large displacement. Measuring small head displacement is often at 250 μ Above m, rollers with high product requirements often result in scrap. After practical summary and analysis, the structure of the six body combined mold has been improved. The improved combined mold is shown in Figure 3, which lengthens the transition sleeve 2 along the conical surface. The working sleeve 3 and the bottom mold 4 form a working sleeve to perform the first assembly within the transition sleeve. Then, the outer sleeve 1 and the transition sleeve 2 are assembled for the second time by a press, and then the screw pads are tightened to ensure the assembly quality.
Practice has proved that the improved combined mold eliminates the eccentricity between the work sleeve and the bottom mold caused by assembly, prevents the small end chamfering deviation, ensures the quality of the roller, improves labor productivity, and achieves good economic benefits.
More about WBM Carbide Cold Heading Dies:
WBM can produce different types and sizes Steel Ball Dies with quality assurance, include: carbide steel ball cold heading dies, Steel ball cold heading dies for national.
Materials: tungsten carbide or mold steel
Main parts for cold heading process: Quill (cut off die), cutter (cut off blade), punch, taper dies. No matter your material is case harden steel or through harden steel, our full set dies can run in a good lifetime.
High precision dies produced according to your drawing. And we can also provide tools design service according to your roller headers.
