Abstract:
A method for making monobloc points for a transporation rail is disclosed. The points include a profiled body having a groove for housing a point rail. The method includes selecting a steel bloom having dimensions at least equal to the outer dimensions of the body and machining the steel bloom to define the profiled body.

Description:
TECHNICAL FIELD 
     The present invention relates to a method of manufacturing points for grooved or tramway rails, and to monobloc points made by application of this method. 
     Without being restricted thereto, the invention more particularly concerns points for tramways for urban transport systems or port installations where the rails are embedded in the roadway surface. 
     BACKGROUND OF THE INVENTION 
     Points for transportation rails are generally composed of an assembly of various components which are of different qualities and shapes and are made to measure either by machining and assembly by hand, usually be welding, or by casting. 
     The fact that it is necessary to use a large number of components of special qualities and shapes greatly complicates procurement and production. 
     The manufacture of points by assembly of these components not only makes automation impossible, but in addition calls for a large skilled labor force, particularly for the welding work. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to provide a new method for manufacturing points of the type described above, which enables the finished product to be improved both through the intrinsic quality of the material and through a reduction of manufacturing tolerances. 
     In order to achieve this aim, the method proposed by the present invention is essentially characterized in that it consists in selecting rolled, forged or other steel blooms having a length at least equal to the length of the points, and, over the entire length, a section at least equal to all the sections of the body, and in that said blooms are subjected to machining exclusively by chip removal for the purpose of forming the outside and inside profiles of the body. 
     The machining preferably consists of automatic milling under programmed control. This machining may be followed by surface hardening heat treatment or by resurfacing by the addition of hard metal. 
     The opposite ends of the points body are preferably fixed by welding to the track rails. 
     The monobloc points produced by the present invention make it possible to apply almost complete automation, human intervention being reduced to control and supervision work. This results in improved productivity and increased production capacity, with better guarantee of the quality and reliability of the end product. 
     The monobloc design is in addition a better guarantee of uniform quality of the finished product, because weak parts, such as for example welds highly vulnerable to stress and wear, are eliminated. 
     In addition, it is possible for the manufacturer to choose the quality of the steel of the blooms, for example in accordance with the stresses, or in accordance with the track in order not to disturb the homogeneity of the latter. Thus, for example carbon steel enables the ends of the points to be weIded to the track, thus eliminating conventional joints and improving environmental conditions by substantially reducing noise. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and characteristics will emerge from the description of one advantageous embodiment given below by way of example and with reference to the accompanying drawings, in which: 
     FIG. 1 shows a schematic plan view of a set of points, and 
     FIGS. 2 to 6 show cross-sections in the sectional planes defined respectively by A, B, C, D and E in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a pair of rails 10, 12 which are extended by points 14 intended to guide a train either onto the pair of rails 10a, 12a or onto the pair of rails 10b, 12b. The points operated in conventional manner, and only the method of manufacturing them, and consequently the profile of the bodies of the points, are different from the prior art. This profile is illustrated by the different sections shown in FIGS. 1 to 6. 
     FIG. 2 shows a cross-section of a body 16 at the tip of a point rail 24. This body 16 of substantially rectangular section preferably has two projecting edges 18, 20 forming the fastening flanges extending corresponding flanges on the rail 10. The body 16 has a groove 22 forming the housing for a point rail 24, the tip of which is shown in FIG. 2. The bottom of the groove 22 is horizontal and forms the slides guide for the point rail 24 enabling the latter to be displaced transversely from the position shown in FIG. 2 towards the right, against the flank, on the opposite side of the groove 22 and vice versa. The left-hand flat top edge of the body 16, extending along the groove 22, forms the tread. An internal longitudinal groove 26 permits the passage of heating pipes (not shown). 
     FIG. 3 shows the same body 16 in a section taken a little further downstream, at the vertical hole 28 passing through the body 16 and serving for evacuation of rainwater and rinsing water. 
     At the point where the section shown in FIG. 4 is taken, the body 16 has a horizontal bore 30 intended to receive the operating means for the point rail 24. 
     FIGS. 5 and 6 show sections of the body 16 at the end of the points. As shown in these two figures, the body 16 is wider at the end of the points, because it must have two grooves 22a and 22b, corresponding respectively to the rails 10a and 10b. 
     FIG. 5 shows a section at the end of the points, particularly where the point rail 24 is widened to provide a tread corresponding to that of the rails 10b and 12a. The point rail 24 may be joined to these rails by welding, as shown at 32, thus permitting a very good transition. The connection may however also be made by means of a joint, in which case the point rail 24 is fastened by means of a key, thus enabling the point rail to be more easily detached. 
     FIG. 6 shows a section through the body 16 taken beyond the junction to the rail 10b and before the junction with the rail 10a, at which point the groove 22b has given way to the groove 36 in the rail 10b. The fastening between the rail 10 and the body 16 is made by bolting. 
     The part of the points situated between the rail 12 and its extensions 12a and 12b is composed similarly to the above description. 
     According to the present invention each body 16 is entirely manufactured by machining, both as regards it external shape and as regards its internal profile particularly the grooves 22, 22a and 22b, the groove 26, the hole 28 and the bore 30. This machining is carried out with the aid of a milling machine, preferably automatically under programmed control. The starting material is a rolled bloom, the quality of the steel of which can easily be determined by the manufacturer of the points. These blooms must necessarily have a length at least equal to the total length of the points and a constant or variable section making it possible, by the milling, to reduce the profile to the different sections which follow one another over the entire length of the body, and of which some are shown in FIGS. 2 to 6. In other words, if the section of the bloom is constant over its entire length, its section must be at least equal to the largest section of the body 16, this section being situated at the end of the points, as shown in FIG. 5. However, this procedure would entail considerable milling to reduce the section of the bloom to the smaller sections of the body 16 at the beginning of the points, as shown in FIGS. 2 to 4. 
     In order to avoid such considerable machining, it is preferable to start with a bloom whose width substantially corresponds to the total of the maximum widths at the flanges 18 and 20 on the body 16 at the beginning and at the end of the points, that is to say the sum of the maximum widths of the sections shown in FIG. 2 and in FIG. 5. This bloom is then divided obliquely in the direction of its length in order to form two identical, symmetrical blooms whose widths vary progressively from the width of the flanges 18, 20 in FIG. 2 to the width of the flanges 18, 20 in FIG. 5, and vice versa. 
     After the body has been formed by external and internal machining of the blooms, it is possible to subject the body to local heat treatment or quenching in order to achieve surface hardening of the parts most subject to stresses. It is also possible to effect resurfacing by welding in order to increase strength locally. 
     Because it is possible to select the quality of the steel of the blooms constituting the starting material, the machined monobloc points according to the present invention can be easily be connected on site to the rails of the track, preferably by welding and in particular by aluminothermic welding, thus enabling the joint between the points and the track to be eliminated and achieving track continuity. 
     While preferred embodiments have been shown and described, various modification and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitations.