SK920085A3 - Spiral member for securing a rail fastener - Google Patents

Abstract

Method of increasing the resistance to pull out of a screw (20) screwed into a receptive substrate (35) which comprises unscrewing the screw and removing it from the hole and then locating a spiral member (140) having an outwardly facing pointed profile in the old threads and screwing the screw into the hole, the spiral member engaging the hole and the screw threadly engaging the spiral member and forcing the pointed profile into the substrate. The bottom end (146 or 182) of the spiral member is shaped so as to be disconnectably engageable by a tool (160) inserted down the centre of the spiral member whereby the force to screw the spiral member into the hole can be exerted from the bottom end of the spiral member. The spiral member is made of intermediately malleable material (as defined herein), the spiral member being turned inwardly and back down the axis at one end to afford a drive pin (182), and preferably being tapered towards the end affording the drive pin. The spiral member is thus deformable by the screw whereby the bottom end of the spiral member can be distorted out of the way of the screw by the screw. A tool for inserting the spiral member is also described.

Description

Technical field

BACKGROUND OF THE INVENTION The invention relates to securing rail fasteners, in particular screw propellers in sleepers, increasing the axial force for pulling out a propeller from sleeper material, in particular sleeper wood, which has partially or totally lost resistance to pulling out the propeller. and counter threads carved in sleeper wood.

BACKGROUND OF THE INVENTION

Wooden sleepers have, as is known, rails mounted on one another by means of propellers mounted on the sleepers, which in turn are provided with threads screwed into pre-drilled holes of smaller diameter in the sleepers. The sleepers are placed on a ballast bed, and when passing trains of varying weight and length, traveling at different speeds, the load fluctuates within wide limits, causing the ballast to shift and squeeze out over time. It is not known whether this is or is the only cause of propeller loosening, but the fact remains that the propellers come out of sleepers over time. This propeller release can be considered as unscrewing. However, from the observations and tests that have been carried out, the authors do not believe that this is the case, but that the threads on the propeller shaft are likely to skip threaded grooves in the sleeper wood. However, the essence of the invention and the problem it solves is not dependent on the correctness of this theory.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the tendency of screw rail fasteners, for example propellers, to be released from railway sleepers by passing trains over time.

SUMMARY OF THE INVENTION

This object is achieved by a helical insert for securing the rail fastener in the receiving material, the head and the screw propeller in the wooden sleeper, increasing the axial force for pulling the propeller out of the sleeper material, especially the sleeper wood, which partially or totally lost resistance to pulling the propeller of wood fibers, by reducing the specific load between the propeller screw threads and the counter-threads carved in the sleeper wood, which consists of a rod of substantially triangular cross-section of a ductile material such as aluminum or aluminum alloy with a base and side walls defining cutting edges coiled about an axis and forming a helical formation having a thread pitch adapted to the helical pitch of the helical propeller such that the helical insert threads fit between adjacent helical propeller threads, one end portion of said helical the helical formation is bent toward the winding axis as a radial retracting arm for driving the insertion tool and further bent in this axis as a helical insert guide pin, bent back from the end of the helical formation into the internal cavity defined by the helical winding.

The helical insert has a cross-section such that it fits between adjacent propeller threads, the thread cross-sectional dimension perpendicular to the longitudinal axis of the helical member (hereinafter referred to as the radial depth of the thread profile) is preferably greater than the propeller thread profile height to which it is assigned. The helical insert is introduced into the threaded hole in the sleeper by its axis along the length of the hole and has at least at this stage an inner diameter smaller than the diameter of the propeller base.

An advantage of the invention is that the helical insert is made of a material that is softer than the propeller but is harder than the timber of the sleeper, so that it can twist and deform and fit tightly to the worn thread in the railway sleeper. This is a great advantage because the level of wear can vary greatly from one old sleeper to another. For use, the spiral wound helix insert is cut into the sleeper wood. The insert is pushed between the old threads in the sleeper when the propeller is screwed back into the hole containing the helical insert. The threads of the helical insert are caught in the wood between the old threads. This results in a remarkably increased tear strength when using simple means.

The problems associated with the relative softness of the helical insert material when it is pushed into the tapped hole are overcome in that the insert is provided at the end with a guide pin adapted to interact with the corresponding shape of the helical insert insertion tool of the invention whose geometry corresponds to the screw propellers used. The guide pin is thus held in the tool and the helical insert can thus be blown into the wood and, once screwed in, the tool can be easily withdrawn again due to its radial recess. Thus, the shaping of the tool with the threaded grooves can advantageously assist in the practical use of the helical insert according to the invention in a good guiding of the helical insert and in maintaining a constant pitch of their threads. At the same time, these grooves prevent the tool from being pulled out only by axial pull, but allow it to be unscrewed in the opposite direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail in the following description by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a sectional view of a sleeper with a portion of a propeller provided with a helical insert according to the invention, partly in axial section by a propeller with a wrapped insert and partly in a front view of the helical insert; FIG. 2A is a side view of a helical insert inserter according to the invention, FIG. 2B is a side elevational view of the lower end of the tool of FIG. 2A seen from the other side, FIG. 2C is a front view of the lower end of the tool from below, FIG. 3 is an axial section, partly in perspective, of a sleeper in a sleeper with a helical insert inserted into the sleeper wood by the tool of FIG. 2A; FIG. 4 is a front view of the lower end of the assembly of FIG. showing the mutual insertion of the tool and the helical insert according to the invention, FIG. 5A is a schematic representation of a helical insert, with the left side in axial section and the right side in perspective, FIG. 5B is a bottom view of the helical insert of FIG. 5A in the direction of the axis from its upper end from which the apparent lower end is bent back to the axis; FIG. Fig. 5C is a cross-sectional detail of a helical insert showing a preferred embodiment of its profile; 5D details, in another enlarged scale, the preferred profile of the helical insert of FIG. 5C and its bearing surfaces on the propeller shaft, and FIG. 6 is a schematic axial section through a bore in a propeller sleeper, showing the propeller completely reintroduced into the bore in a view and a helical insert according to the invention in section.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 shows a vertical axial section through a rail fastener-propeller 20 in the right half of the figure, divided by the axis 21 into a sectional view and a sectional view. The pitch 22 of the threaded propeller is in this case tapered from top to bottom as indicated by the inclination of the surface line 23 of the propeller body to the axis 21. This inclination or conicity is typically 1 mm to 102 mm of the length of the threaded propeller shaft 20. The heel 22 carries a single-threaded screw thread 26 which is in contact with the timber of the sleeper. The thread 26 has an upper surface 27 at an angle A of approximately 70 ° to the longitudinal axis 21 of the propeller 20 and an lower surface 28 at an angle B of approximately 30 ° to the same axis 21 of the propeller 20.

The thread 26 projects at a distance 29 (radial depth of thread) from the heel line 23 of about 3.1 mm or within a wider range of 2.5 to 3.5 mm. Propellers 20 used in other countries differ from those used in the UK, but are approximately the same size. The helical insert 140 is adapted for other countries to have the same or similar dimensions.

When the propeller 20 is screwed for the first time into the sleeper wood 35, the wood 35 is adjacent to the heel surface and the propeller thread. The state that occurs after the period of operational use is shown schematically on the right side of FIG. 1. The surface of the wood part 36 that is first, i.e. prior to operational use, touching or lying close to the base of the propeller thread, pulled back therefrom and the surface of the wood 35 in contact with the top surface 27 of the propeller was greatly reduced.

The exact reason why the sleeper wood 35 shrinks in this way is not known, but it is possible that it is repelled from the foot 22 of the propeller thread 20 by the thread itself in the release process. Corrosion or wood decay caused by water between the sleeper wood 35 and the propeller metal body 20 may also be involved. The authors found by testing that although the propeller 20 could be screwed in as tightly as it was originally, it could be concluded that In fact, the resistance of the assembly to pulling the propeller 20 out of the wood 35 has actually decreased very substantially, often up to only 25% of the original value. Of course, the straight thrust does not correspond to the forces occurring between the propeller 20 and the sleeper wood 35 in operation, but this change is surprising when the propeller 20 appears to be tightly and firmly clamped to the sleeper.

The British propeller 20 is 19 cm long (although some are longer, for example 20.3 cm for special purposes) and the threaded area tapered from 22.4 mm at the lower end to 24.1 mm where it passes into a shank without the thread surrounded at an operating length of about 56 mm through a plastic sleeve extending through the stool 56 to the lower surface of the upwardly rounded collar 161, the lower surface of which exerts a pressure on the stool 56 through the plastic sleeve 57. The propeller 20 is terminated by a rectangular head 160.

The propeller 20 is usually made of mild steel, optionally galvanized, to reduce corrosion in operation. Thread pitch is 13 mm. The sides of the threads and the height of the threads have already been discussed.

Again, as shown in FIG. 1, in which a helical insert 140 according to the invention is shown in cross-section in its right part and in a left side elevational view, the helical wound rod of the helical insert 140 has a non-circular cross-sectional equilateral triangle with sides corresponding to the thread profile walls 171, 172, 173. one wall forming the base 173 is substantially parallel to the line 145 inclined to the axis 21 of the propeller 20 at a greater angle than the animal bead line 23 connecting the heel of the propeller teeth 20. The cross-sectional base 173 of the helical insert 140 corresponding to the triangle base forms area. The base 173 abuts the heel 22 of the propeller threads 20 between adjacent threads of the propeller shaft 20 and, as shown in FIG. 1, is equally long or slightly longer than the length of the heel 22 in the longitudinal direction of the propeller 20.

At the same time, the tip of the transverse triangular cross-section of the helical insert 140, facing away from the axis of the helical insert, forms a cutting blade 174 for cutting the screw member 140 into the wall of the sleeper wood 35. The radial depth 175 of the helical insert 140 is in this embodiment (perpendicular distance) from the base 173 to the top

5,2 mm.

The lower last thread of the helical insert 140 has an inner diameter of 15 to 16 mm before being inserted into a sleeper hole. The end portion of the last thread in the form of a guide pin 182 is bent to the axis 21 and back up into the helix of the helical insert 140, as shown in FIG. 5A, thereby forming a member for engaging a tool not shown in FIG. 1, wherein the helical insert 140 can be screwed into a bore in the sleeper from which the old propeller 20 has been turned and removed. In FIG. 3 is a view of the insertion tool of the screw member 140 in operation during insertion into a sleeper.

The reintroduction of the propeller 20 is shown in FIG. The propeller 20 is shown partially retracted and with the lower end 60 approaching but not yet touching the last thread of the helical insert 140. Only a portion of the propeller 20 to the right of the axis 21 is shown in order to illustrate the shape of the helical insert 140. FIG. 6, showing the propeller 20 fully inserted into the helical insert 140 with the triangular diameter of its forming rod and into the wood hole 35 of the sleeper with the plastic housing 57 separating the unscrewed portion of the propeller shaft 20 from the chair 56 and the end pressed to the side of the hole in the sleeper.

The heel 22 pushes each thread of the helical insert 140 into the shallow groove 37 (FIG. 3), which is deepened and received by the locking means, i. helical insert 140, in the wood 35 sleepers. The threads of the propeller shaft 20 cut a new groove 61 in the fret 36 of the sleeper wood 35 between the turns of the helical insert 140.

Fig. 6 illustrates the helical insert 140 inserted into the sleeper hole and the propeller 20 completely screwed in again. The drive pin 182 was pushed downward and to the side by the ends of the propeller shaft 20. The helical insert 140 also rotated downwardly in the sleeper threads and was pushed outwardly by the propeller threads 20. As shown in FIG. 6, there are now seven turns on the tool instead of the eight turns shown in FIG. 3 and FIG. 5A prior to introduction. The upper thread 58 is now empty (see Fig. 6 /

It has been found that the pulling force of this assembly completely introduced into the sleeper is of the order of 3 here softwood sleepers and 6 here hardwood sleepers, which means that this force is substantially restored or nearly restored to a value corresponding to the wood strength around the sleeper hole. .

The helical insert 140 can be manufactured, for example, by extruding a desired triangular profile (which in the first embodiment has a wall 171, 172 and a base 173 with a length of 6 mm and a radial depth 175 of a 5.2 mm thread profile). However, in order to ensure that the profile base 173 bears flat on the mandrel, it is also necessary to twist the triangular profile. Twisting of the extruded profile during winding around the dark changes the cross-section due to the elongation at the outer apex corresponding to the cutting edge of the edge 174, the radial depth 175 of the thread profile decreasing slightly after elongation, for example by 5 to 10 or 15%.

The triangular metal wire is 520 mm long before being wound on a mandrel and produces seven turns in a clockwise direction with an inner diameter of 25 mm, and must also be twisted clockwise between its ends by 1 1/2 turn, ie 540 °. The mandrel is conical so that the helical insert 140 extends from the inner diameter of the lowest thread 15 to 16 mm to the inner diameter of the uppermost thread 17 mm.

The above-described helical insert 140, formed of an HE9 aluminum alloy, was tested for elastic elongation. Lengthened by 44.5 mm if clamped and held at the upper end and a 54.5 kg weight attached to the lower end and returned to 140 mm (from 114 mm from the bottom of the clamp to the lower edge of the lower end) ) for one second after relieving, maintaining the load on the load for 10 min. Thus, the axial length of the helical insert 140 has increased substantially.

This alloy according to DS 1474 no. The 6063 TF has a 0.2% stress value of 160 MPa, a tensile strength of 185 MPa, and an elongation of 7%. It has the following composition:

0.2 to 0.6% Si, 0.35% Fe, 0.1% Cu, 0.1% Mn, 0.45 to 0.9% Mg, 0.1% Cr, 0.1% Zn, 0.1% Ti and the rest being aluminum.

Other compositions of aluminum alloys considered to be suitable for the purpose are given in Tab. 1 including their physical properties.

Tab. 1

Tensile strength Elongation MPa% σ 0,2%

MPa

alloy

HE9-6063 TB 70 130 14 HE30-6082 TB 120 190 14 HE30-5083 0 125 275 13 HE9-6063 TE 110 150 7

Thus, materials with a tensile strength of 130 to 275 MPa and an elongation of 7 to 14% are generally considered to be suitable.

For comparison, the helical insert 140 was formed from a mild steel wire with a diameter of 5 to 6 mm and a length of 100 mm and with a thread pitch between 13 mm threads, i. values close to, if not equal to, the pitch of the propeller thread to be used.

The helical formation of the insert, in contrast to the conventional helical spring, tapered conically when used from its upper end to its long end to a degree similar to that of the propeller with which it will be used. The helical insert has an elastic elongation of 6.4 mm per 1 second when the upper part is held and 54.5 kg is attached to its lower end and returns to 114 mm (from the original length of 114 mm from the lower surface of the clamp to its lower end) within one second after relieving while maintaining the load for 10 minutes. The helical insert was therefore not extended.

Such compositions made of steel are relatively heavy and, since they are intended for use by ordinary railroad workers Despite the need for special tooling (except for the tool), the weight of the helical members can play an important role so that light metals are preferred. Surprisingly, it has been found that aluminum is both easier to screw in and to give the pulling force similar to that of mild steel inserts when used with a circular cross-section.

It has been found that profiles with a cutting edge have a lower tendency to split wood than profiles with a circular cross-section. Furthermore, it has been found that the helical insert 140 should be made of a material hard enough to penetrate the wood, whether it be hardwood such as mahogany or softwood used on sleepers and yet soft or malleable to accommodate the propeller threads 20 without leaping out of them.

The helical insert 140 is clamped between the threads dr ^! The propeller 20 and the sleeper timber 35 into which it is pushed and to adapt to the threads appear to need to be truly drawn in the individual turns as it is screwed by the propeller 20. The helical insert 140 is screwed into the sleeper by about 3/4 of the threads when the propeller 20 is screwed in, but it may also be partially elongated. The author is not exactly aware of this, but it has been found that the above aluminum alloy is very suitable for use with mild steel propeller 20 and soft or hardwood used on sleepers in the UK. Other materials having hardness, ductility, ductility or elongation characteristics similar to those of aluminum alloys may also be envisaged.

Fig. 2A to 5B show in more detail the helical insert 140 and the preferred shape of the insertion tool for introducing the helical insert according to the invention, wherein FIG. 5C and 5D show details of a preferred helical insert shape.

In Figures 2, 3, 4, a tool of the shape of a turned propeller 20 to be secured in a worn sleeper hole by a helical insert 140 according to the invention is shown. The rectangular head 160 and ring collar 161 ib remain unchanged, the upper portion of the shank 162 may be turned to slightly reduce its diameter to ensure free passage through the stool 56, and the shank 163 at its first thread contact is sufficiently turned to prevent it grip inside the sleeper hole.

The threads are turned into faces 164 whose conicity is greater than that of the propeller 20 with which the screw member 140 is to be used, i. 13 to 17 mm, or 14 to 18 mm compared to 16 to 17 mm, with a lower value for the helix end. A rectangular groove 165. is defined between the surfaces 164. The axial length of the grooves is, for example, 6.3 to 7 mm, and it is advantageous to have a clearance on each side of the thread of the helical member 140 such that the helical member 140 is relatively free on the tool. the length of each groove is 101% or 105% to 120% or 130%, for example about 115% of the maximum axial length (for example 5 mm) of each thread of the helical insert 140. The depth of each rectangular groove 165 is about 2 mm.

The lower end of the helical insert 140 is bent to its longitudinal axis 21 and further up to a position along the axis 21 by about one thread length to form a drive pin 182. The drive pin 182 lies transversely about 6 mm and the lower part of the insertion tool has a longitudinal axial bore 166 which is tight but free for the axially upwardly bent portion of the drive pin 182 of the helical insert 140, the bore may have a diameter of about 7 mm (see FIG. 4). The axial bore 166 is in the axial direction longer than the length of the drive pin 182. The lower end of the insertion tool has a radially extending radial stop 167 away from the bore 166 (FIGS. 2, 3 and 4). This radial stop 167 engages a radially retracting arm 201 of the helical insert 140 extending inwardly to the guide pin 182 and as shown in FIG. 4, it is preferably rounded to ensure that the malleable drive pin 182 of the helical insert 140 is not cut through the hard metal of the insertion tool.

The shortest length of the drive pin 182 and the axial bore 166 at which the intended function is achieved is unknown, but the length-diameter relationship must be such that a sufficient grip is created to prevent a radial stop 167 from pulling the drive pin 182 from the longitudinal ax. 16, such as the helical insert 140 is fully inserted into the sleeper hole with its upper end below the level of the upper sleeper surface. It is thus secured in the sleeper. If this did not occur, the upper thread would be lifted and it would be difficult to screw the propeller 20 into the helical insert 140. Friction of the upper threads and pushing their end into the wood of the sleeper prevents the helical insert 140 from turning out of the sleeper hole.

It should be noted that if such gripping does not occur, the end portion of the drive pin 182 would be pulled out of the longitudinal axial bore 166 of the tool, and the ductility of the materials used would deform the helical insert 140 to accommodate the groove in the insertion tool. thereby stopping being screwed in and the insertion tool would only rotate in the stationary helical insert 140 in the sleeper hole.

Fig. 5C shows in detail and in cross section the preferred shape of the profile of the helical insert 140. The cross-section is a substantially equilateral triangle with a protruding tip forming the cutting edge 174 and a base 173 forming the bearing surface. The height or radial depth 175 of the thread profile of the helical insert 140 is 6.1 mm when it has been extruded before winding on the mandrels. After twisting, it shrinks to 5.7 mm.

The apexes of the base 173 are impinged so that the profile forms an arrow shape symmetrical about the line joining the apex corresponding to the cutting edge 174 of the profile with the center of the base 173 so that the embossed profile can be wound on the mandrel in any direction to form a helical insert 140. The profile is asymmetrical about a line a line connecting the apex corresponding to the cutting edge 174 and the center of the base 173 and parallel thereto. The chamfers 190, 191 are such that the length of the bearing wall 173 is 4 mm, the length of each chamfer that is straight is 1.3 mm, and the profile width 192 measured at the ends of the chamfers 190, 191 is 5.5 mm. These chamfers 190, 191 define the contact abutment surface of the base 173 and, since they are symmetrically positioned, allow the extruded wire to be wound in any direction. Only the bevel facing the drive pin 182 has the effect of a longitudinal bearing surface using the helical insert 140, as shown in FIG. 5D.

Profile symmetry is not critical. The only essential feature of the profile is that the lower surface should correspond to the angle of the upper surface of the screw thread on the shaft of the propeller 20.

Some rail lines use larger sleeper holes. For example, for the English Western Region, the radial depth of the thread profile 175 in the extruded state would be 7.4 mm, t. j. the triangle is equilateral and would be reduced to twist when twisted

6,9 mm. The dimensions of the base 173, the chamfer, and the respective angles remain the same as described with respect to FIG. 5C. In a variation of the embodiment, the end of the drive pin 182 is thinner and protrudes about 5.7 mm transversely to align with the bore 166 of the longitudinal axial tool without the need to change the tool.

As mentioned above, the distance between the tips of the adjacent propeller threads 20 is 12.7 to 13 mm and the thread height is 3.1 mm. The heel length is typically 4 mm and the helical insert 140 fits tightly between adjacent threads, the lower bevel angle of the screw member is the same or nearly the same as the angle of the upper thread of the propeller so as to allow tight fit of the longitudinal bearing surface and the material of the helical insert 140 used, i The aluminum alloy of which the helical insert 140 is formed may deform when introducing the propeller 20 in the immediate vicinity of the propeller thread 20. Since the upper chamfer on the propeller insert has a steeper angle than the propeller thread lower face, there is no substantial surface contact between them.

The force required to pull out the propeller 20 using the profile shown in FIG. 5C 3.5 t for softwood and 6.51 for hardwood.

Some of the propellers 20 have a slightly curved plane instead, and the ductility of the material of the helical insert 140 used is again advantageous in that it allows its deformation for a tight fitting on t; the curved heel when introducing the propeller.

Claims (1)

A helical insert for securing a rail fastener in the receiving material, in particular a screw propeller in a wooden sleeper, increasing the axial force for pulling the screw propeller out of the sleeper material, especially the sleeper wood, which partially or totally lost resistance to pulling the screw propeller between the propeller screw threads and the counter-threads carved in the sleeper wood, characterized in that it is formed by a rod of substantially triangular cross-section of a malleable material such as aluminum or aluminum alloy with a base (173) and side walls (171, 172) defining cutting edges (174), spirally wound about an axis (21) and forming a helical formation having a thread pitch adapted to the pitch of the screw propeller such that the threads of the helical insert fit between adjacent screw propeller threads, one end portion of said screw the ovary formation is bent towards the winding axis (21) as a radial retracting arm (201) for driving the insertion tool, and further bent in this axis (21) as a guide pin (182) of the helical insert (140) bent back from the end of the helical formation into the internal cavity defined by the helical winding.