KR20000010768A - Metal mold manufacturing method - Google Patents

Abstract

PURPOSE: A method is provided to manufacture the metal mold of especially a radial, thrust or linear bearing cage that is made into iron alloy. CONSTITUTION: A flat and linear typed strong strip(1) as a carbon steel that contains C22, is tempered in a continuous furnace like the method of the spring strip based on DIN 17 222. A pocket(2) accepting a roller body is stamped in advance on the strip softened by tempering. Therefore a twist and a shape change are not generated by making the shape and size change flat.

Description

Mold manufacturing method

Steel roller bearing cages are produced in large quantities in various ways. They can also be produced as steel sheets or steel pipes, for example by drawing, stamping and bending. (DE-OS 21 47 169, DE-OS 21 47 171). In particular, highly stressed cages can further improve their strength and wearability, for example by thermal or thermo-chemical treatments such as surface hardening or nitriding. (DE-OS 25 56 745).

It is also known to produce radial bearing cages from strip material by stamping the pockets that receive the rollers from the strip, bending the strips in a circle, and optionally welding the ends that connect to each other (FR 12 56 601, US 22 88 564). This method of making cages from curved strips is also used for thrust bearings (DE 21 46 056 C3).

The treatment used for the improvement of properties results in torsional shape and dimensional change, especially in the case of fine cages, ie cages with small wall and web thicknesses, ie in extreme cases, these parts become useless. As such, this dimension- and shape change of the material in the heat treatment occurs due to the overlap of the volume change due to deformation and conversion caused by intrinsic stress caused by heat.

The present invention relates to a method for manufacturing a mold of a cage of a radial, thrust- or linear bearing, in particular of iron alloy, in which a roller cut is formed by stamping on a metal strip, and the mold has hardness, strength. It may be subjected to heat or thermo-chemical treatment to achieve certain properties such as and wear conditions.

1 is a flat strip in the state of the work;

2 shows the steel strip stamped with a pocket and

Figure 3 is a cage welded by rolling into a stamped steel strip.

Accordingly, the present invention is based on the task of manufacturing a shape so that the torsion is prevented despite the application of the treatment method for improving such characteristics.

According to the invention, this problem is solved by thermal or thermo-chemical treatment before stamping the pocket according to the component set forth in claim 1.

In this way, the volumetric changes in deformation and transition conditions caused by intrinsic stress have elapsed before completion of the final form of the part, which leads to thermal or thermo-chemical treatment of the raw material and the unavoidable shape and dimensions of the part due to its application. The change is eliminated.

The thermal method may be regarded as a heat treatment method in a known method, whereby certain processing and / or use characteristics may be improved or achieved by thermal action without intentional change of chemical composition.

The thermo-chemical method is a thermal and chemical action that involves changing chemical components and tissues, especially in the boundary layer, in some cases to reach certain use characteristics.

In Claims 2 and 3, the metal strips are bent in a circle and welded at ends that meet each other.

The material engineering characteristic is that the contact seam does not have a martensite structure due to the predetermined hardness, and accordingly, the malhensite welded iron is generated, which may cause abrasion action on roller bearing parts such as a runway.

Since the welding heating time is kept short in the range below AC₁-temperature, the heat-treated strip structure does not have any intrinsic annealing effect and, in a more advantageous way, does not soften at all in the weld zone transient region lower than the original strength. The weld inherent stresses generated are widely removed by sufficient material toughness.

In another form of the invention, the strip undergoes surface hardening or nitriding according to claim 4. In the case of surface hardening, the steel is annealed to a temperature in the range of 850 to 1,000 ° C. in solids, liquids or gases which emit carbonol with a slight carbon content of 0.05 to 0.20% which cannot be actually hardened, as is known. . Carbon diffuses into the material injected at this time, so that the carbon content is small in the nucleus and contains a kind of solid solution which increases at the boundary.

Nitriding is a thermo-chemical method like surface hardening. The surface is then concentrated with nitrogen and carbon. The purpose of this thermo-chemical treatment is to further adjust these properties such as hardness, resistance and wear resistance.

Even more advantageous is the annealing treatment according to claim 5, which is contemplated by maintaining a duration of about 1 hour at about 180 ° C. or by maintaining a duration of about 5 seconds at about 350 ° C. according to claim 6. Is done.

This tempering treatment stabilizes the formed structure, thereby increasing the resistance and removing the inherent stresses of the weld.

The invention is explained in more detail in the following examples which follow a cage of radial roller bearings.

The flat, straight steel strip 1 shown in FIG. 1 is C22, a carbon steel containing 0.22% C, and is tempered in a continuous furnace, as is the typical method of a spring strip according to DIN 17 222.

The strength achieved by tempering has a tensile strength of 250 to 350 HV or 850 to 1.100 N / mm 2. In this temper-cured strip 1, now the pre-stamping pocket 2 receiving the roller body according to FIG. 2, as shown in FIG. 3, the perforated strip 1 to the cage 3 along the radial direction. The ends 4, 5 which are bent to meet each other are connected to each other by a welding method.

The obvious advantage of good use properties by hardening or tempering in this way is no longer the disadvantage of torsion and deformation as the unavoidable shape- and dimensional change is advanced to a flat, non-stamping strip of material.

Embodiments are also applicable to planar or linear bearing arrangements where the reciprocating motion on one plane takes place, for example, in a machine guide. In this case, of course, the metal strip is flat and does not roll on the annular cage, but is welded at both ends. However, the application of the method according to the invention for producing a thrust cage is also possible without problems.

It is used as a method for manufacturing iron alloy molds for forming cages of various roller bearings.

Claims (6)

A pocket (2) for receiving the roller body by stamping on the metal strip (1) is formed and a thermal or thermo-chemical treatment is carried out on the mold to obtain the desired properties of hardness, strength and wear and the iron alloy, in particular lady A method for manufacturing a mold for a cage of an all-roller bearing thruster bearing or a linear roller bearing, Heat-chemical treatment of the metal strip (1) before the stamping of the pocket (2). The method of claim 1, The metal strip (1) is characterized in that it is bent in a circle. The method of claim 2, The metal strip (1) is characterized in that it is welded at its ends (4,5) after circular bending. The method of claim 1, The metal strip (1) is characterized in that it is surface hardened or nitrided and carburized. The method of claim 3, Circular bending and welding of the metal strip (1) is characterized in that the tempering (tempering) heat treatment. The method of claim 5, Tempering is maintained for about one hour at about 180 ℃ or about 5 seconds to about 350 ℃.