DE3943038A1 - Three=dimensional item production method - bends bars after heating initially in common plane at different points - Google Patents

Abstract

The method produces items bent in three dimensions from bar stock, particularly spring clips holding track rails in position. A blank of the necessary length is delivered from a magazine into the position where it is heated to shaping temp. after which a manipulator passes it to a station where it is gripped and bent in succession by tools acting in straight lines in a common plane. A second manipulator then transfers it to a die forming a negative of the finished article, and to which it is clamped. As the die is turned, the blank is pressed into the channels in it by a roller. The die is then locked to prevent it turning further. Tools working in straight lines at the necessary angles press the remaining portions into the deepest recess in the die. After they and the roller have been retracted, ejectors in the die separate the finished article from it. ADVANTAGE - Low cost and constant quality, utilising material readily available.

Description

The invention relates to a method for producing in a spatial waveform bent objects Rod material, in particular for the manufacture of railway rails depressing springs serves.

At present the railroad tracks are depressing Springs made by cold forming. That on the unwound dimension shortened material is by means of geometric dimensions of securing bending tools in Eccentric presses shaped to the desired size. The number of Forming operations and the tools required depends on the complexity of the desired shape.

The production of the SKL-3 rail-type spring exemplified in FIG. 1 is accomplished, for example, by Voßloh and Schmidt (FRG) in five separate operations in eccentric presses. During molding, the workpieces experience partly plastic (figurative) and partially elastic shape changes. The elastic deformation, the so-called springback, is to be considered in the design of the tools. The geometric dimensions of the tools are to be chosen so that they hold the dimensions of the workpiece, despite the springback within the specified tolerances. This is achieved in that the workpieces are bent over during the molding by a value corresponding to the amount of springback. However, the amount of springback does not have a constant value but depends on the strength properties of the material and changes as it changes. The springback, which takes place to varying degrees, can not be completely corrected (compensated) by the design of the tool, which leads to the scattering of the dimensions of the workpiece. This scattering can be reduced by reducing the dispersion of the strength properties of the starting material to a minimum. Therefore, the manufacturers of such components place special conditions on the quality of the basic material that go beyond the standard requirements.

For example, there is the spring-depressing spring of the Type SKL-3 manufacturing company Voßloh for those used by her Material composition 38Si7 DIN 17221 instead of in the Standards set the following stricter conditions:

Further regulations are available for the strength properties of the material. In the standards is for the condition of the Material only the hardness (HB 217) specified. The company Voßloh lays down the following additional rules:

tear strength 680 N / mm² strain 24% contraction 57%

The above rules ensure that the Change of springbacks during bends remains within such limits, the one within predetermined tolerances making the Allow work pieces. The described Manufacturing method has the following disadvantages:

• - To manufacture is a special regulation appropriate material quality required what the Production costs of the product increased. During the domestic manufacturing of the components carried out Experiments have shown that z. Eg the Hungarian Metallurgical base material with respect to the regulations the standards do not provide stricter tolerances can; Thus, so with the known technology the Production from domestic base material not solved become.
• During the forming operations, the tool has to Reduction of springback at the bends with small radius to forge the workpiece, d. H. local plastically deform. These blacksmith tool marks damage the surface of the workpiece, causing the Lifetime influenced later.
• - Divided into five separate operations Manufacturing process has a greater need for machinery, Tools and workers as if the manufacture of the Workpiece by contracting operations in less Shaping positions would take place. A bigger one Operation concentration, however, is affected by the circumstance Prevents (complicates) that in the cold deformation occurring large forming forces a robust Require tool training.

The larger dimensions and because of the compensation the resilience claiming larger shaping paths Tool elements can be in the work space, its dimensions determined by the workpiece, not housed become.

The invention has set itself the goal of enumerated Deficiencies of the previously used method to avoid and one cost-effective production of rail-crushing Feathers, in all respects the original equivalent  are using the standards specified in the standards Rules corresponding home base material to enable.

The most obvious solution would be the conventional one Manufacturing process with the difference that the Shaping operations are performed with warm material. The related experiments have done following experiences delivered.

The workpiece has such a cooling rate that, in a single warm-up, the molding operation can be performed in at most two pressing machines. A study carried out between the operations reheating one hand has a cost-increasing and the other part - due to the increased scaling and Kohlenstoffausbrennens - reduce the quality.

Below the temperature of the hot working, the workpiece points a lower strength on, which is on with the Tool touching surfaces, especially at the points where there is a relative movement between the workpiece and the tool, leads to significant surface damage.

These lead to the formation of local voltage spikes, whereby the life is reduced. The geometric ones Ratios of the workpiece do not allow in the matrices and stamp rolling support forming elements that during the Reduce the surface friction occurring during deformation would incorporate.

Even taking into account the above statements is by the Method according to the invention the stated goal as follows reached.

The deformation is warm. The shaping operations become grouped into two shaping positions. In the first Shaping position, those operations are performed  through which the settled in a plane so-called flat shape of the workpiece is formed. In the second Shaping position then become those operations performed from the plane shape of the workpiece form necessary spatial forms.

The inventive method is based on the production of Shaft depressing spring SKL-3 described in more detail. In the drawing shows

Fig. 1-3 seemed depressing spring SKL-3 in three views,

FIGS. 4-7 illustrate the forming operations to be performed in the first forming position in the order of their execution;

Fig. 8 shows the mounting of the flat unwound workpiece for the spatial deformation,

Fig. 9 shows the process of the spatial deformation,

Fig. 10, the final operation of deforming,

Fig. 11 shows the separation of the finished, bent to a spatial shape piece.

The unwound length accordingly cut round steel blank 1 is guided from a magazine in heating position, heated by direct resistance heating within 10-12 seconds to the shaping temperature and forwarded by means of a manipulator in the first shaping position, where according to FIGS. 4, 5, 6 and 7, the operations A , B , C , D are performed.

The workpiece is determined in the operation A with a centrally disposed clamping device 2 .

Thereafter, the ends in the operation B by means of elements 3 are simultaneously inflected. After removing the deforming elements 3 , the workpiece is shaped in the operation C by means of moving and symmetrically arranged tool elements 4 in the direction indicated on a shape of an exploded letter M. In the following operation D , this shape is closed by means of a tool element 5 and thus brought into the final shape of a planar structure 10 .

The tool elements 3 and 5 have rollers 6 and 7 on their surfaces contacting the workpiece. These rollers 6 and 7 roll on the surfaces of the workpiece and thus the damage of the surface can be prevented.

The angle α of the line of action of the tool elements 4 and the distance x of the point of application are chosen so that only a minimum relative movement can take place during deformation at the point of contact of the workpiece and the tool. Thereby, the damage of the workpiece can be prevented, at the same time between the clamping device 2 and a steering roller 8 located between the counter-support 9 and the tool element 4 section of the absorbing material on the action of the tool element 4 material is subjected to a slight pulling and thus follows exactly the desired shape , After completion of the operation D , the determination of the workpiece (Figure) 10 is released and the workpiece 10 is lifted out of the forming plane and then conveyed by a manipulator in the second shaping position. Here, the workpiece is fixed by means of a fastening element 11 on the jacket of a spatial shaping cylinder 12 and pressed by a roller 13 to the jacket. Thereafter, the spatial forming cylinder 12 is rotated, whereby the roller 13 presses the workpiece into a model corresponding to the forming cylinder 12 of the desired spatial shape. After about one-third revolution of the forming cylinder 12 , a roller 14 is pressed against the jacket as shown in FIG. 9, wherein the roller 14 calibrates the workpiece. After a rotation of 360 ° of the forming cylinder 12 is fixed and with the aid of a linearly moving tool element 15 , the central nose portion of the workpiece is pressed in the manner illustrated in Fig. 10 in the lower part of the model. Thereafter, the forming members 13 , 14 , 15 are removed from the surface of the forming cylinder 12 , the fixing member 11 is loosened, and the piece 17 bent into a spatial shape is separated by means of ejecting members 16 from the surface of the forming cylinder 12 in the direction indicated in FIG ,

The most important advantages of the method according to the invention are the following:

• - It becomes unnecessary, basic materials with special Properties to use. It will be a production Materials whose quality allows the Hungarian (less stringent) standards.
• - By the much gentler shaping operations Surface damage can be prevented and thus Can products with regard to the fatigue limit more advantageous quality.
• - A high concentration of shaping operations becomes which allows a more productive, more economical Manufacturing can be achieved.

Claims (1)

A method for producing curved in a spatial curve objects made of rod material, in particular railroad depressing springs, characterized in that a one of the unwound length corresponding blank is guided out of a magazine in heating position, is heated to the molding temperature, forwarded by a manipulator is set a suitably selected point of the workpiece and in this position, the workpiece is bent depending on the complexity of the desired shape with a plurality of co-acting, linearly movable forming bodies in subsequent steps on a developed planar shape, then the workpiece the shaping plane is lifted, is forwarded by means of a manipulator and is brought into contact with a cylinder jacket having a negative shape corresponding to the desired spatial shape, ie f the workpiece is set at the contact point on the cylinder jacket, that at least one forming roller, the axis of which is parallel to the axis of the cylinder jacket is pressed against the cylinder surface, the cylinder is rotated by the required angle and the workpiece moving in common with the cylinder is bent by means of the rollers in the model (the channels) of the cylinder jacket, that then the cylinder is set against rotation and further bending claiming portions of the workpiece by means of aligned on the cylinder jacket at a suitably selected angle, linearly movable elements in the lower recesses of the model are then removed, then the forming rollers and forming elements are removed from the surface of the workpiece and the workpiece is separated with the requirements of the arranged Auswerfelementen of the surface of the cylinder.