CS271020B1 - Method of trapezoidal-section half-finished product production - Google Patents

Abstract

The method of trapezoidal cross section semi-product manufacture from a semi-product of a circular cross section is suitable primarily for production of flexible packing pieces. In comparison with present method optimum material through forming within the entire cross section area and, therefore, a uniform structure and mechanical values on the surface and even in the core are achieved. At least the first passage is done under pressure vertically to a longitudinal axis of the semi-product, and at least the last passage is carried out under versatile pressure. The relative ratio reduction following three up to five passages amounts to 18 up to 40%. The successive passages show a relative reduction of 4 up to 12%.<IMAGE>

Description

SUMMARY OF THE INVENTION The present invention provides a method for producing a trapezoidal cross-section from a circular cross-section particularly suitable for the production of flexible washers.

The prior art methods of manufacturing a cold trapezoidal blank for making flexible washers do not guarantee uniformity of mechanical values throughout the cross-section, as well as compliance with the required edge rounding tolerances. Due to the unevenness of the mechanical values, the profile distorts during winding and during the production of its own washers to break.

In order to avoid uneven mechanical values, a first hot rolling operation is performed by pre-rolling. However, this process is unsuitable for wire processing, as the relative depth of decarburization and scale is considerable for small profiles. The degradation of the surface layer is only slightly reduced by annealing in the protective atmosphere, since the actual hot forming process takes place outside the protective atmosphere. Continuous scaling and dirt removal is ineffective in hot wire processing and are then rolled into the surface. The trapezoidal cross-section thus treated also exhibits non-uniform mechanical properties.

In the prior art technologies, the final shape was achieved by drawing in hard metal dies from a cold or hot rolled blank. The profile thus obtained was annealed as required. When the workpiece is pulled, the profile shrinks around the periphery to the final size. The considerable amount of heat generated by rubbing the workpiece surface against the die is difficult to control and dissipate and is a major cause of the unevenness of the mechanical values of the final profile.

Improved mechanical values are achieved when rolling the workpiece by rolling rings. Production of own rolling rings is very technologically demanding, because it has to guarantee by appropriate design of the cavity and locks full closure of the cavity forming the caliber.

The aforementioned drawbacks are overcome by the method according to the invention relating to the manufacture of a trapezoidal cross section blank from a circular cross section blank suitable primarily for the production of flexible washers. At least the first pass is performed by pressure perpendicular to the longitudinal axis of the workpiece and at least the last pass is performed by all-round pressure. The total relative reduction after three to five passes is 18 to АО 4. Subsequent passes are a relative reduction of 4 to 12%.

Said treatment achieves an optimum deformation of the material throughout the cross-section, a uniform structure and uniform mechanical values on the surface and in the core. The trapezoidal cross-section is dimensionally accurate. The stability of the mechanical values also makes the workpiece so produced free of undesirable stresses and does not distort the profile during winding. The surface is perfectly smooth and of the same carbon content as the core of the profile.

An exemplary embodiment describes a method of manufacturing a trapezoidal blank from a 9.4 mm diameter circular cross-section obtained from a 10 mm controlled, optionally patented, wire. The procedure for calibrating a 10 x 6.5 x 5.5 mm trapezoidal profile blank from said blank is shown in the attached drawing. The total number of passages comprises three pressure passes perpendicular to the longitudinal axis made by rolling and one final pass through the all-round pulling pressure in a carbide die or roller draw.

passage design cross-section semi-finished product F _a = 69.39 mm 2 1. rolling F = 65.80 mm ^ 2. rolling 2 = 62.40 mm 3. rolling F ₃ = 59.10 mm ² 4. drawing or rolling F ^ = 56.00 mm²

CS 271020 Bl

The relative reduction in the individual passages is then F - F, Г1 = ° F 1 5.17 4 0 - = 4; ^F 2. 5.16 '4 ^F 2 - ГЗ ⁼ _F ^r 2 ^F 3. 5,13 4 no ^F 3 ^F 4. 5.24 h 4 Total proportional the reduction is then: F - f _a ^Гс ' ^F o 4 23.9 * 4

SUBJECT OF THE INVENTION

Claims (2)

SUBJECT OF THE INVENTION A method of manufacturing a trapezoidal blank from a circular blank, particularly suitable for producing flexible washers, wherein at least a first pass is performed by pressure perpendicular to the longitudinal axis of the blank and at least the last pass is carried out by a versatile pressure, characterized in five passages are 18 to 40 4. 2. Method according to claim 1, characterized in that the successive passages are a relative reduction of 4 to 12 * 4. ’