SK98198A3 - Manufacturing elastic rail clamps - Google Patents

Description

In a method of manufacturing a rail clamp (13) that is used to fasten a rail to an underlying rail plate or rail sleeper, the clamp is made of a billet formed of a log that is compacted such that the billet has rounded edges (edges). The method may be applied in the manufacture of a rail clamp of the type comprising a pair of parallel elements (14) bent in a D-shape such that the front is adapted to be inserted into the rail flange when said front is formed by respective free horizontal elements, and a base adapted to be received in a slot of a rail plate, rail sleeper, or anchoring device mounted to the rail plate or rail sleeper.

-1Manufacture of flexible rail clamps

Technical field

The present invention relates to the manufacture of flexible rail clamps used in a rail fastening system, and more particularly, but not only, to a method of manufacturing rail clamps positioned perpendicular to the rails.

BACKGROUND OF THE INVENTION

A flexible rail clamp is described in U.S. Patent 4,313,563 issued to Young. This clamp is designed for use with the usual manufacture of an arm that fits the base of the flexible clamp.

The previously contemplated methods for producing such a rail clamp have encountered the problem of mixing in the finished clamp at high stress locations, which could lead to fatigue failures.

Therefore, it is desirable to produce such clamps in a manner that does not lead to the formation of shaking at high stress locations.

The essence of the invention _?

The invention provides a method of manufacturing a rail clamp for fastening a rail to a rail plate or sleeper, wherein the rail clamp comprises a base adapted to be inserted into a slot in the rail plate or sleeper, or to another anchoring device mounted on the board or sleeper, and a pair of parallel. which extend from the base to the rail retainer, the parallel elements being curved such that the rail retainer is close to the base. The method of manufacturing a rail clamp comprises:

i) forming the workpiece by bending a rod of a certain length to form the workpiece; ii) compressing the workpiece to form a flat part with a reduced thickness of the rod material; iii) deforming the workpiece so formed into a clamp.

The previously contemplated methods of manufacturing rail clamps of the type described in US 4,313,563 also had the drawback that the clamp had to undergo a so-called coin-collecting operation to remove forging stress concentrations near sharp corners. In addition, the previously used manufacturing methods required molded clamps to undergo a bending operation in which the clamps are bent to exhibit a durable and advantageous initial deployment. coin and bending operations, if the bar has a circular shape and the workpiece is pressed so that the blank acquires rounded edges.

Overview of the figures in the drawing

For a better understanding of the invention (and its uses), we will use examples of its implementation, together with the accompanying drawings, in which:

1 to 5 show the steps of the previously used method of manufacturing a flexible rail clamp; FIGS. 6 to 10 show the steps of the manufacturing method of the present invention; FIG. 11 shows a blank used in the previously used method; FIG. 1 to 5, FIG. 13 shows a perspective view of the workpiece

14 is a perspective view of a blank manufactured by the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The steps of the prior art manufacturing method are shown in Figures 1 to 5. The manufacturing process begins with the production of a rectangular blank 1 (Figure 1). The blank is normally made of steel.

The rectangular blank is then divided into two U-shaped blanks (FIG. 2). Each U-shaped blank 2 forms the base of the rail clamp.

The U-shaped blank is cut to the correct length by cutting and its sharp sides are cut to smooth edges (Fig. 3). Cutting and embossing is performed on the heated blank. Rounding the edges with the coin punching operation is necessary to prevent stress build-up at the finished clamp.

Said embossing is a well-established process by which the properties of the edge formed by cutting material are improved to the properties of the edge formed by hot rolling. The process is usually carried out by pressing in a pair of dies. The rough blank is placed in the dies and clamped so that rounded edges are formed on the blank. This operation is a critical operation with regard to the lifetime of the spring clip made of sheared flat material and requires a high degree of quality control during production.

In the previously realized method, the blank is hot cut and embossed into the shape shown in FIG. 4 by folding the free ends so as to form finger-shaped parts 7 that rest on the rail when using the clamp. The bases are made by bending the middle part of the blank

-4 in U shape. The base is designed for connection with the base plate with which the clamp will be used.

The clamp is further bent such that the base 5 of the clamp is held firmly between the two jaws 6. A force is exerted on the fingers 7 so that the clamp is bent. The force is then released. The application and release of force may be repeated several times, for example three times, and then the clamp is removed from the jaws. This operation creates a terminal Ä with the correct shape and the desired initial voltage distribution.

In FIG. 6, 7, 8 and 9, the various steps of the production method according to the invention are shown.

6a and 6b show a round rod, usually a steel rod, that bends between the ends to form a starting U-shaped piece 10 with two arms 14 connected by an arcuate portion 16. In the piece of Figure 6a, the two arms are parallel to each other. in Fig. 6b, the arms converge towards the free ends.

The part 10 is then flattened to form a blank 11. In FIG. 7a and 7b, a blank 11 made from the part of FIG. 6a and 6b. The blanks are made by heating the part 10 and pressing it in an open die. The arrangement of the press plates depends on the final desired clamp shape. An example of the press plates is shown in FIG. The part is placed on the lower die 22. The upper die 21 is pressed against the part 10 in the direction shown by the arrow f in FIG. The blank is compressed until the upper die 21 hits the stops 24 located on the lower die 22. The shape of the surface 23 of the upper die 21 that is in contact with the blank provides the blank 11 with the desired shape. The shape of the surface 23 is exaggerated in FIG. Other forms of shaped surface could be used to form the blank 11 shown in FIG. 7a and 7b. Because an open die is used in this operation, the inner and outer side sides 18, 20 of the arms 14 are not

The inner surface of the arcuate portion 16 is limited by the press plates, so that the material of the part 10 can flow undisturbed in the direction away from the center line of the arms 14, and also inwardly at the arcuate portion 16 when the part is compressed. As a result, while the top and bottom of the panel 10 are flattened, the inner and outer sides acquire a rounded shape without sharp edges.

Alternatively, the part 10 may be flattened using a closed die to obtain the blank 11 (FIG. 9a). 9b and 9c show a cross-section along the line IX -IX and IX -IX.

to cc

The shape of the die used in the closed die is such that excess material flows around the center line of the blank, with all outer edges of the blank having a corresponding radius, since the die itself can be made without sharp edges (edges) and can have all edges appropriately rounded. Final cutting off of excess material is a desired operation before the blank is heat treated to its final shape.

The thickness of the blank 11 can be varied according to the clamp shape requirements and the level of compression occurring in each part of the finished and installed clamp. In the example shown in Fig. 7a, the end region 12 of the blank 11, corresponding to the arcuate portion 16 of the part 15 in Fig. 6a, has been tapered. Such tapering may be required in order to allow the clamp to engage the base plate. The shape of the other parts of the blank 11 is selected so as to optimize the stiffness and voltage distribution of the finished clamp. For example, high voltage areas should be thicker than low voltage areas. Thinner areas with less voltage allow greater deflection of the clamp during use.

As shown in FIG. 10, the flattened blank 11 is here transformed into a clamp 13 of the desired shape. The terminal of FIG. 10 is a terminal of the type disclosed in U.S. Pat. U.S.

-64,313,563, although the manufacturing method could be applied to other clamp shapes, for example, clamps described in International Patent Application PCT / GB96 / 00319 or in U.S. Patent 3,067,947. The clip 13 is formed by bending the free ends of the blank 11 to form the fingers 14 that rest on the rail when in use. The base is formed by bending the tapered end 12 of the blank 11 through the middle portion of the blank.

An advantage of the manufacturing method described with reference to FIGS. 6 to 10 is that the manufactured blank has smooth rounded edges that have not been cut. The rounded edges serve to prevent stress concentration without the use of an embossing operation. In addition, blanks manufactured using an open die (Figs. 7a, 7b, 8) instead of a closed die (Figs. 9a, 9b, and 9c) do not require trimming.

The ability to vary the thickness of the workpiece, and hence the clamps, can result in a much better voltage distribution than was the case with the previously used manufacturing methods. Changing the thickness of the clamp in this way allows the bending operation to be reduced or omitted, and so the clamps can be manufactured by the method of the invention much more economically than in the first methods. The manufacturing methods shown in FIGS. 6-10 have further in FIGS. 11-14.

The semi-finished product 2 (FIG. 2) of the method is cut from made of rolled contain impurities or, in the advantage that will be described, used in the previously considered rolled steel sheet, steel ingots. Such ingot inclusions, especially in the middle regions of the ingot. As shown in FIG. 11, these inclusions 31 are centered in the central region of the rolled metal sheet 30. The blanks 32 and 33 are cut from the metal sheet 31b, and so the finished clamp has edge inlets as shown in FIG. 12. Line AA and BB of FIG. 11 shows the positions of the highest voltage at the finished terminal. In FIG

-Ί Three trimmed edges (edges) with inserts 31 are shown in the region of the highest voltage at the finished clamp. The fatigue fracture can begin and spread just from these inclusions.

In the manufacturing method according to the invention, the inclusions remain inside the clamp, but in the finished clamp they do not occur at the edges. As shown in FIG. 13, the bars 31 of the bar material are centered within the bar 34. If the bar is pressed as described, the bars 31 are held within the molded blank 35 and hence further away from the edges of the finished bar. 14, as shown in FIG. Such displacement of the mixes in the clamp reduces the likelihood of fatigue fracture at the clamp.

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Claims (6)

a sleeper, when adapted to the board, the clamps (13), a clamp (13) lying thereon to receive a rail which serves the board or includes in the slot of the sleeper, or A method for manufacturing a rail for attaching a rail to a rail base (12) in a rail in an anchoring device mounted to a rail plate or rail sleeper, and a pair of parallel elements (14) that extend from the base (12) to the rail connecting portion where they are parallel elements (14) curved so that the rail connecting parts lie close to the base (12), the manufacturing method comprising: i) forming the part (10) by bending a given length of rod to form a pair of projections, ii) pressing the part (10) to form a flat blank (11) with reduced thickness, iii) deforming the blank to form a clamp (13) . Production method according to claim 1, characterized in that the rod used is a log and the part (10) is pressed so that the blank has rounded edges. Production method according to claim 1 or 2, characterized in that during the pressing step the material of the part (10) has the possibility of deforming in a direction parallel to the plane comprising the center line of the projections. The production method according to any one of the preceding claims, characterized in that the pressing step comprises an open die operation. The production method of any one of claims 1 to 3, wherein the pressing step comprises a closed die operation. Production method according to claim 5, characterized in that, after the pressing step, the excess material is cut off from the blank. 'ZASEfc .. ^ίί λ <ο _ Τ '7 \ (() ()) _ ~ yr ~ ρΐ OJ ΖΣΖΖΖΖΖΖΖ2 Et _ ο r ~ l ΈΛύ ^ _.