GB2378143A

GB2378143A - Beams their formation and their use as a trackway

Info

Publication number: GB2378143A
Application number: GB0118424A
Authority: GB
Inventors: David Thomas Weller
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-07-28
Filing date: 2001-07-28
Publication date: 2003-02-05
Also published as: WO2003011491B1; AU2002314392A1; GB0118424D0; WO2003011491A1

Abstract

A beam is formed from a rectangular strip of metal 11 having Laser cut parallel longitudinal edges by, first, bending the strip, using a jig arrangement, about two fold lines respectively inset from the longitudinal edges of the strip, such as to create two upstanding marginal flanges 33a, 33b. Next, the so-flanged sheet is bent about a longitudinal central fold line such as to create a longitudinally-folded sheet of V-form cross-section, but with in-turned flanges at the mouth of the V-form section. Finally, the V-form folded sheet is braced using either a metal strip 39 or external constraint members that embrace the V-form folded sheet at intervals therealong. The beam may serve as a trackway for a machine tool, a tool-carrying carriage having wheels rotatable about vertical axes, with the wheels in running contact with the trackway at surfaces adjacent to the bend positions of the flanges.

Description

BEAMS, THEIR FORMATION, AND THEIR USE AS A TRACKWAY This invention relates to a method of forming a beam, to beams formed using the method, and to apparatus, such, for example, as wood-working lathes, in which the beam is employed as a trackway for a carriage.

Problems are commonly experienced in machine tools as a result of the natural deflection of beams called upon to support running carriages. The loop: increase in beam stability-- > increase in beam-depth section-- > increase in weight-- > increase in deflection increase in cost in construction in order to increase stability, is frequently encountered by machine tool (and other) designers.

According to the invention, a method of forming a beam, a beam formed using the method, and an apparatus incorporating the beam so formed as a trackway for a carriage, are as set out in the claims contained in the claims schedule hereof, the wording employed in said claims, being, notionally, set out here, mutatis mutandis, also.

The method of forming beams and beams and apparatus in accordance with the invention are hereinafter set out with reference to the accompanying drawings in which: Fig. 1 depicts a flat metal sheet prior to its formation to a beam in accordance with the invention; Fig. 2 shows the first stage of formation, from the sheet of Fig. l, of the beam; Fig. 3 shows the second stage of beam formation;

Figs. 4 to 9 show, in cross-section, an apparatus, in use, in the process of forming the flat sheet of Fig. l to the state depicted in Fig. 3; Fig. 10 shows a beam in cross-section, being a sheet folded as shown in Fig. 9, and with a first form of bracing means; Fig. 11 shows a beam in cross-section, being a folded sheet as shown in Fig. 10 and with second bracing means, being a variant of the bracing means depicted in Fig. 10 ; Fig. 12 shows a beam in cross-section, being a folded sheet as shown in Fig. 9 and with a bracing means of an alternative form to that of Fig. 10 or Fig. 11 ; Fig. 13 shows, pictorially, the beam and bracing means of Fig. 12; Fig. 14 shows an apparatus comprising a beam as depicted in Fig. 11, constituting a trackway and a trolley runnable on wheels along the trackway; Fig. 15 shows a variant of the arrangement of Fig. 14; and, Fig. 16 shows an apparatus comprising a beam as depicted in Fig. 11 constituting a trackway and a trolley slidably runnable on the trackway.

The flat metal sheet 11 is first cut such as to ensure that the longitudinal edges 13a, 13b, respectively, are accurately straight and parallel to one another. For the formation of beams suitable for use as trackways for the tool-carrying carriage of a machine tool, a lathe, for example, the flat metal sheet 11 from which the trackway is to be formed, should have edges that are parallel to

one another to within an accuracy of width/length parallelism of the order O. 01mm/lOOmm. Whilst such accuracy in parallelism of the edges of the metal sheet might be achieved by other means, current practice favours the use of Laser cutting methods.

The sheet 11 having been cut accurately to a width X with the edges 13a, 13b, of the sheet with a requisite parallelism, the sheet is converted to the form represented in Fig. 3, using the apparatus depicted in each of Figs. 4 to 9.

The apparatus comprises an anvil 15, an adjustably fixable stop 17, and a press tool 19.

The anvil 15 comprises an elongate steel block 21 in the upper surface of which there is a V-shaped channel 23 extending lengthwise of the block 21 between two horizontal coplanar surface portions 25a, 25b.

The stop 17 is constituted as an elongate steel bar 27 having an accurately flat face 29. The bar 27 is adjustably fixably connected to the block 21, with its face 29 spaced accurately, with requisite spacing from the line of the apex of the V-shaped channel 23 to extend parallel to the direction of length of the channel, with a parallelism of the order five times greater than that between the edges 13 of the metal sheet 11. Such an order of accuracy may be achieved using optical methods.

Conventionally, however, such accuracy is achieved empirically, applying manual fine angular adjustment of the stop 17.

The press tool 19 which, also, is of steel, has an elongate nose portion 19a of V-shaped cross section, the angle of the nose portion 19a being less than that of the V-shaped channel 23 of the block 21.

In forming a beam, a sheet 11 is brought (Fig. 4) to lie flat upon the coplanar surface portions 25a, 25b, of the block 21 with one 13a of its edges pressed firmly against the face 29 of the block 21.

With the sheet 11 so supported, the action of the press tool 19 and the block 21, at entry of the tool 19 into the channel 23, to an extent determined by a depthtravel limiting stop (not shown), results (Figs. 2 and 5) in the bending of the sheet 11 about a fold line 31a inset from the edge 13a of the sheet 11 to produce an upstanding flange 33a of predetermined height along one of the longitudinal margins of the sheet.

The sheet 11 is, next, turned around through 180 degrees thereby to present (Fig. 6) the other of its longitudinal edges 13b for abutment with the stop 17, and the action of the press tool 19 and block 21 is repeated, the sheet 11 being bent (Figs. 2 and 7) about a second fold line 31b, inset from the edge 13b with a spacing identical to that of the fold line 31a, thereby to produce, in the sheet, an upstanding flange 33b extending along the other longitudinal margin of the sheet.

The two lateral flanges 33a, 33b, of equal angle, normal in the example, with respect to the sheet material 33c, therebetween, having been formed as aforesaid, the adjustably-fixable stop 17 is reset to a position such

that (Fig. 8), with the flanged sheet 11 supported on the upper surface portions 25a, 25b, of the block 21, with the flange 31a pressed against the face 29a of the stop 29, the longitudinally-extending lines defined by the apices of the V-shaped nose portion 19a and the V-shaped channel 23, of press tool 19 and of the block 21, respectively, are at positions such that the upon operation of the press tool, the sheet material 33c is bent (Figs. 3 and 9) about a longitudinal central fold line 35 to form walls 37a, 37b, inclined to one another at, in the example, a right angle, the inclined walls 37a, 37b, and the flanges 33a, 33b, being symmetrical, at 45, that is to say, with respect to the plane P containing the junctures of said inclined walls with said flanges.

The final step in the formation of the beam comprises reinforcing the innate stiffness of the folded sheet, as represented in Fig. 9, bracing it against bending under load.

To this end, the final step may (Fig. 10) comprise the provision, within the mouth of the folded sheet depicted in Fig. 9, of bracing means having the form of a strip 39 of sheet steel, longitudinal edges 41a, 41b, respectively, of which are parallel with one another, the strip 39 being united, by tack welds between the mutually inclined walls 37a, 37b, and the edges 41a, 41b, respectively, of the strip.

The bracing strip 39 may (Fig. 11), instead of being wholly flat, be provided with longitudinally-extensive

marginal flat portions 43a, 43b, respectively, each at an angle such that these may lie in face to face contact with the inclined walls 37a, 37b, spot welds uniting the flat marginal portions with said inclined walls 37a, 37b, at intervals along said marginal portions. In either case, the folded form of Fig. 9 is, whilst the strip 39 is being tack or spot welded, held between faces 45a, 45b, of two rigid bodies.

An alternative method of bracing the folded form, shown in Figs. 12 and 13, comprises clasping the folded form with a multiplicity of external constraint members, as 47, spaced apart at intervals along the folded form as depicted in Fig. 9. Each constraint member 47 comprises a body 49 of flat sheet steel cut-away such as to define a re-entrant recess, the boundary of the recess being such that first and second portions 51a, 51b, respectively, thereof match the external local contour of the folded form shown in Fig. 9, with a snug fit around each of the junction lines 31a, 31b, between the flanges 33a, 33b, and the inclined walls 37a, 37b, of the folded form.

Except in the neighbourhood of such junction lines, there is clearance 55 between the inclined walls 37a, 37b, and the boundary of the re-entrant recess of the member 43.

A primary application for a beam produced as hereinbefore described is as a trackway for the tool carriage of a machine tool, a lathe, for example.

Such trackway is represented schematically in cross-section in Fig. 14. The carriage 57 has two pairs of wheels, one wheel-pair 59, only, of which is to be seen

in Fig. 14, said wheel-pairs being spaced apart fore and aft.

The wheels, as 61,63, of each of the two wheel-pairs, are rotatable about laterally equi-spaced vertical axes, as Y'-Y', Y"--Y".

As may be observed in Fig. 14, one 61 of the wheels 61, 63, is trapped against movement, other than rotary movement about the axis Y'---Y', first and second peripheral surfaces 65a, 65b, of the wheel 61 being in contact, respectively, with first and second surfaces 67a, 67b, the one 67a on the inwards facing surface of one 33a of the flanges, the other 65b on the inwards facing surface 37a'of the inclined wall 37a, at a position adjacent to said one flange 33a. The second wheel 63 is trapped, as before, against movement, other than rotary movement, first and second peripheral surfaces 69a, 69b, respectively, thereof being in contact, respectively, with first and second surfaces 71a, 71b, the one 71a on the inwards facing surface of the other 33b of said flanges, the other 71b on the inwards facing surface of the inclined wall 37b, adjacent to said other flange 33b.

In the apparatus described with reference to Fig. 15 the wheels 61,63, of the carriage 57 have peripheral surfaces 65a, 65b ; 69a, 69b, respectively, that are in contact with appropriate ones of the outwards facing surfaces 67a, 67b, 71a, 71b, of the flanges 33a, 33b, and of the inclined walls 37a, 37b, as the case may be.

In the apparatus of Fig. 16, the carriage 57, suitably

the tail-stock of a lathe, has a slideable runner part 73 which as before is constructed, arranged and adapted to cooperate with the beam such as, by sliding movement along the beam, to enable positional adjustment of the carriage along the trackway.

Claims

CLAIMS 1. A method of forming a beam, being a method which comprises: bending a body of flat sheet metal, having longitudinally-extensive, substantially parallel, edges, about notional parallel fold lines, respectively inset with respect to said parallel edges, such as to render said sheet metal body to a channel-form, that is to say, a body having a flat web portion with upstanding lateral flange portions; bending said web portion about a longitudinal medial fold line thereof such as to convert said web portion from a flat to a substantially V-shaped channel part; and, subjecting the inclined walls of said channel part to the action of bracing means serving to oppose any tendency of the channel part to bend under load.
2. The method as claimed in claim 1 in which the lateral flange portions of said channel are at equal angles with respect to the web portion of the channel.
3. The method as claimed in claim 1 or 2 in which said bracing means comprises a strip of sheet metal having longitudinal edges parallel with one another, said strip being disposed within said V-shaped channel and being united with said walls by welds between the strip and said walls at intervals therealong.

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4. The method as claimed in claim 3 in which said bracing strip is united with said walls at tack welds along the edges thereof.
5. The method as claimed in claim 1 or 2 in which said bracing strip has longitudinally-extensive marginal flat portions at an angle such that these lie in contact with said walls, and spot welds unite said flat marginal portions with said walls at intervals along said marginal portions.
6. The method as claimed in claim 1 or 2 in which said bracing means comprises: a multiplicity of bracket members spaced apart externally along said V-shaped channel, being bracket members having opposed re- entrant portions within which said flanges and adjacent portions of said walls have a snug fit.
7. The method as claimed in any preceding claim in which said web portion is bent to a V-shaped channel the inclined walls of which subtend an angle the magnitude of which is such that said inclined walls and said lateral flanges make angles of equal magnitude with respect to the plane containing the opposed lines defining the junctures of said inclined walls with said flanges.
8. The method as claimed in claim 7 in which the web portion is bent such that inclined walls and said flanges make angles of 45 with respect to said plane.

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9. A method of forming a beam, being the method substantially as hereinbefore described with reference to Figs. 1 to 9 together with Fig. 10, Fig. 11, or Fig. 12 of the accompanying drawings.
10. A beam produced using the method as claimed in any of the preceding claims.
11. An apparatus which comprises: a beam as claimed in claim 10 to serve as a trackway, and carriage means constructed arranged and adapted to co-act with said trackway such as to be held captive thereto whilst being permitted movement therealong.
12. An apparatus as claimed in claim 11 in which: said carriage means comprises: first and second wheels respectively rotatable about first and second laterally spaced vertical axes, said first wheel being trapped against movement, other than rotary movement, with first and second peripheral surfaces thereof in contact, respectively, with first and second surfaces, the one on one of the flanges, the other on the channel wall surface adjacent to said one flange, and said second wheel being trapped, as before, against movement, other than rotary movement, with first and second surfaces thereof in contact, respectively, with first and second surfaces, the one on the other of the flanges, the other on the channel wall surface adjacent to the other flange.

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13. An apparatus as claimed in claim 11 in which said carriage means comprises: slide means which bridges said trackway and which is held captive thereto whilst being permitted sliding movement therealong, being slide means having first and second lateral surfaces thereof in contact, respectively, with first and second surfaces, the one on one of the flanges, the other on the channel wall surface adjacent to said one flange, and having third and fourth lateral surfaces thereof in contact, respectively, with first and second surfaces, the one on the other of the flanges, the other on the channel wall surface adjacent to the other flange.
14. An apparatus comprising a beam, constituting a trackway and a carriage slideably runnable along said trackway, all as substantially hereinbefore described with reference to the accompanying drawings.
15. A method of forming a beam substantially as hereinbefore described with reference to Figs. 1 to 9 together with Figs. 10,11, or 12 of the accompanying drawings.
16. A beam substantially as hereinbefore described with reference to the accompanying drawings.