IE56330B1 - Machining apparatus - Google Patents

Abstract

In apparatus for machining an elongate section of machineable material, the elongate section to be machined is advanced into a machining station 2 of the apparatus through an aperture 42. Four milling cutters 16a, 16b, 16c and 16d are arranged in an array surrounding the path of advance of the section and cut elongate recesses in the four corners of the advancing rectangular section material. Guide plates 17, 18, 19 and 20, also disposed in an array surrounding the path of advance of the section, prevent displacement of the advancing section in any direction transverse to its direction of advance. Edges of the plates 17, 18, 19 and 20 slidingly engage against or abut respective faces of the advancing section. The apparatus may be adapted to machine slots or recesses in faces of the section and-also for face milling an elongate section, while guide plates 17, 18, 19 and 20 are adjustable in position or interchangeable to accommodate sections of different sizes.

Description

This invention relates to apparatus for machining an elongate section of machineable material. In particular the Invention relates to apparatus for milling elongate slots or recesses in such sections and to apparatus for face milling elongate sections.

In many engineering applications, there Is a need for elongate sections of machineable material such as special steels In which the sections are provided with elongate recesses or slots or have crosssectional dimensions which must be controlled within accurate limits· Such elongate sections may be used to provide shorter sections having such slots or controlled dimensions by parting off portions of an initially longer elongate section of material. Slotted elongate sections in particular are used for rock drill cores, the cutting elements of carbide material being secured In the slots or recesses.

Sections of this type may be produced by extrusion, In the course of which slots may readily be formed In the material and high dimensional accuracy may be guaranteed.

Where suitable extruded sections are not available and production levels are sufficient, high-cost machining processes such as broaching may be employed to provide the desired finished product, neither 20 extrusion nor such high-cost machining operations are appropriate for small production runs of such products. / f -2It is accordingly an object of the Invention to provide apparatus for < machining an elongate section of machineable material which will be suitable for the economical treatment of short production runs.

* According to the Invention there Is provided apparatus for machining an elongate section of machineable material, comprising a machining station, drive means for advancing a said elongate section through the machining station to effect machining contact between each of a plurality of cutting tools mounted at the machining station and said elongate section at a plurality of locations disposed around the periphery of the section during advance of the section through the machining station, and guide means for engaging a said advancing elongate section at a plurality of locations disposed around the periphery of the section to substantially prevent displacement of the section in any direction transverse to the direction of advance of the section, at least in the region of said machining contact between the cutting tools and the section.

Preferably the machining station Is fixedly located on a frame of the apparatus and the drive means includes a carriage for advancing a said elongate section through the machining station. The carriage may be displaceably mounted on the frame of the apparatus and drivable along the frame relative to the machining station in the direction of section advance. The carriage is most suitably provided with means such as a vice or chuck for gripping a said elongate section. The carriage may be positioned relative to the machining station so that In use of the apparatus It may push a substantially rigid elongate section through the machining station. The drive of the carriage for machining advance of the elongate section may take place by a lead screw or feed shaft. The drive to the lead screw or shaft may be derived.from a main drive motor of the apparatus in a manner known In the machine tool art.

In a preferred embodiment of the apparatus of the invention, each cutting tool may be a milling cutter. The locations disposed around the periphery of the section at which machining contact is effected % may be the corners of a square or rectangular elongate machineable m -3section and the milling cutters may he arranged to cut out elongate slots or recesses in these corner regions. Alternatively the cutters 9 may be arranged to mill the faces of the elongate section. In a preferred arrangement of the apparatus of the Invention, the machining * station includes a support structure In which the milling cutters are mounted on shafts, each said shaft being drivingly associated with an input shaft of the machining station. The various shafts on which the respective cutters are mounted may be drivingly interconnected by means of gears. These gears may be spur gears for slot or recess milling, or in the case of face milling, helical or bevel gears for transmitting the drive through angled driving connections. The input shaft of the machining station may be drivingly associated with the drive motor of the apparatus in a manner known in the machine tool art.

The guide means preferably comprises a plurality of guide surfaces for engaging the surface of the advancing elongate section at a plurality of locations disposed around Its periphery. Each guide surface preferably slidingly engages a portion of the periphery of the section. The guide surfaces are located in the region of the machining station, to restrain the section against transverse displacement as close as possible to the region of machining contact between the section and the cutting tools. Where the cutting tools are arranged to machine slots or recesses in the elongate section, the guide surfaces may extend continuously through the region of machining contact. Alternatively separate guide surfaces may be provided upstream and downstream of the region of machining contact. This arrangement Is required in particular when face milling of the elongate section is in question. With face milling, it Is not possible for sliding engagement or abutment of the guide surfaces to exist in the actual region of machining contact, at least so far as the surfaces to be machined are concerned.

The guide surfaces may each be defined by an edge region of a guide ί plate. To provide suitable restraint or guidance for an elongate section of square or rectangular cross-section, four guide plates may he provided,, each guide surface defined by an edge of one of the guide -44 plates being disposed at right angles to each adjacent guide surface, so that each guide surface applies restraint or control to one of the four faces of the elongate section.

* Means are preferably provided for adjusting the disposition of at 5 least one of the guide surfaces relative to the section to be advanced so that different sizes of section may be accommodated In the apparatus. Each guide surface should extend substantially parallel to the direction of section advance, at least during a machining operation, and the adjusting means may allow fine alterations in the disposition of the guide plate to ensure such parallelism. Where four plates are provided, the adjustments of three of the plates may be. semi-permanent, to the extent that their dispositions are not altered when handling successive sections of a particular size, while the fourth guide plate may have a degree of float, so that It may accommodate minor variations In section size from one piece of material to another.

When dealing with square or rectangular elongate sections, the guide means may include a channel member having three guide faces defined by the inside surfaces of the web and flanges. This channel member may then co-operate with a single opposed plate-form guide member defining the floating guide surface for sliding engagement with the fourth face of a rectangular section to be machined.

According to a further aspect of the Invention, there Is provided a method of machining an elongate section of machlneable material In which a said elongate section Is advanced through a machining station to effect machining contact between said section and each of a plurality of cutting tools mounted at the machining station at a plurality of locations disposed around the periphery of the section, and displacement of the section 1n any direction transverse to Its direction of advance Is substantially prevented, at least In the region of machining contact between the section and the cutting tools, by guide means engaging the advancing elongate section at a plurality % of locations disposed around the periphery of the section. -5The apparatus and method of the invention provide a form of mechanical extrusion*, in which elongate slots or recesses may be cut , in the section or the faces of the section may be machined accurately to predetermined dimensions. The section to be machined Is advanced through an array of cutters substantially surrounding It In the region * of machining contact, so that machining takes place at at least a plurality of locations around the periphery of the section and even over its whole peripheral surface, where face milling Is in question.

The apparatus and method of the invention are particularly economical for small production runs, where the expenses of providing extruding dies or costly broaching tools could not be justified. They may also be adapted to the production of a variety of elongate products and In particular an elongate section may be machined as a single unit and subsequently parted off Into a multiplicity of shorter components, each of which has the elongate features or machined dimensions.of the original section.

An embodiment of the Invention together with some modifications thereof will now be described by way of example having regard to the accompanying drawings, In which Figure 1 is a general front view of apparatus according to the Invention; Figure 2 Is a pictorial view of a cut-off portion of a section machined by the apparatus of the Invention; Figure 3 is a schematic ptctorlal view of part of the guide means for controlling the disposition of an elongate section to be machined in the machining station of the apparatus of Figure 1; Figure 4 is a schematic section on the line X-X of Figure 6, showing from the upstream end the guide means 1n abutment against a machined section; Figure 5 Is a rear elevation of the machining station of the apparatus of Figure 1; Figure 6 Is a bottom view of the machining station of Figure 5;.

Figure 7 shows pictorially, detail of the bottom guide plate, positioning arrangement; . Figure 8 Is a detailed section view on the line VIII-VIII of Figure 6 showing one adjusting screw for the front guide plate; < -6Figure 9 is an end view of the machining station of Figure 5 from the downstream end; Figure 10 is a cross-section of the machining station of Figure 5 on the line X-X of Figure 6» i.e. looking In a downstream direction; Figure 11 shows a channel-form guide means, and Figure 12 shows in schematic outline a face-milling arrangement of the apparatus of the invention.

As shown in Figure 1, apparatus 1 according to the invention for machining an elongate section, such as an elongate bar section, has a /. machining station 2 mounted on a bed 3 within which the drive motor or motors of the apparatus may be accommodated. Drive means 4 for advancing a section to be machined throuyh the machining station 2 Includes a carriage 5 which can travel to and fro in a longitudinal direction along the apparatus of the Invention On guide bars 6. The carriage 5 is mounted on the guide bars by means such as suitable sliding bushes. A lead screw or feed shaft 7, driven by the motor of the apparatus, provides motorised drive of the carriage 5. The carriage is provided with a vice or chuck, the operating lever 8 of which Is shown, by means of which an elongate bar section 9 may be locked relative to the carriage 4. When the bar 9 is thus locked in position relative to the carriage, drive may be applied to the carriage by means of the lead screw or feed shaft 7 to advance the bar 9 to the machining station 2 at a controlled rate. The rate of feed may be selected and varied by conventional gear box or other change speed means, in conjunction with and depending on the machining speed chosen for cutters in the machining station.

Figure 2 shows a parted-off section of a rock drill core produced by machining an elongate section in accordance with the Invention. The parted-off portion 10 is of substantially square cross-section and has longitudinally extending recesses 11 at the corners of this crosssection. A bore 12 extends through the portion 10, also In the longitudinal direction, and may be provided after the portion Is parted-off from the original section 9. The original section may be 1 or 3/8» square and initially provided In ten foot lengths. For rock drill cores, a suitable grade of steel is EN30B· Each recess 11 -7has side faces 13 and 14 extending perpendicular to the respective side faces of the portion 10 which they intersect. Remote from these · Intersections, a diagonal face 15 of the recess extends between the mutually perpendicular faces 13 and 14. These recesses are cut In the elongate section by a suitably profiled array of milling cutters, as * described subsequently. Tolerances apply to the sizes and locations of the recesses and typical values are 0.003 Inches across the flats between the side walls of adjacent recesses and a similar figure diagonally across the corners of the portion 10, between the bases 15 of the recesses.

The arrangement for cutting slots of this kind In an elongate section is shown In schematic pictorial form In Figure 3. The shape of each recess 11 is determined by the profile of the milling cutter which cuts that recess. The disposition of the elongate section relative to the milling cutters is controlled by guide members which prevent displacement of the elongate section in any direction transverse to its direction of advance against the milling cutters during the cutting operation. Four milling cutters 16a, 16b, 16c and 16d are indicated in chain dotted outline in Figure 3 and define an array of cutters substantially surrounding the path of advance of the elongate section. Top and bottom guide plates are Indicated by 17 and 18 and a side guide plate by 20, this being the front guide plate in the arrangement of Figure 1. The guide plates also substantially surround the path of advance of the elongate section. A further side guide plate is also provided forward of section 9 as depicted In Figure 3 but is omitted from this Figure for clarity. Elongate edge surfaces of these guide plates slidingly engage or abut against the surfaces of the advancing elongate section 9 on all four sides or faces of the section and prevent it from undergoing any significant displacement transverse to Its path of advance. The plates extend continuously through the cutting region, where the milling cutters remove material from the edges of the section, for which purpose the top and bottom plates 17 and 18 have scooped-out central regions extending away from their edges remote from their guide edges, to accommodate the shafts for the milling cutters. The plates may be urged closer towards the section 9 by the application of an adjusting force to portions 17a and -817b of plate 17 and regions 18a and 18b of plate 18. The arrangements for carrying out this adjustment are described subsequently. The plates may be likewise moved away from the path of advance of section 9, so that a section of larger dimensions may be accommodated.

Similar adjustments are provided for the front side guide plate 20 and the other side guide plate to the rear of the advancing section. By varying the relative adjustment of end 17a relative to end 17b, In the case of plate 17, it is also possible to ensure that the guide surface edge of the plate is substantially parallel to the direction of advance of the section, within the required limits of tolerance. The other guide plates may be similarly adjusted. The guide plates are most suitably formed from hardened and ground flat steel stock.

Figure 4 shows schematically the engagement of the guide plates 17, 18, 19 and 20 against the respective faces of a square section elongate member 9 to be machined. The outer edges of top plate 17 and front and rear plates 20 and 19 are retained In displaceable guide mounts 21, which are moved towards and away from the section 9 by suitable adjusting screws housed within covers 22. These plates are semi-permanently adjustable, in that their adjustment Is not generally altered from one piece of material to another, but they are set to accommodate a particular size of elonyate material to be machined. In order to cope with minor variations In elongate section dimensions, the bottom plate 18 is displaceable towards and away from the elongate section 9 In slots or grooves 23 extending vertically In respective end walls 26 of the support structure or housing of the machining station. Adjusting screws 24 having tapered ends extend through these end walls 26 of the housing, and their tapered faces 55 each engage a respective lower corner of guide plate 18, so that the displacement of the guide plate towards and away from the section 9 may be varied by inwards and outwards displacement of the screws 24. Variation of the location of the contact region between the plate and the conical end of the screw causes the plate to move up or down along the slot 23 as required. This arrangement provides a degree of float”, sufficient to accommodate any minor differences In dimensions as between one piece of material to be machined and another. Figure 4 also shows the top cover 25 of the mathlnlng station support structure or housing, as -9well as the front and rear housing «Mils 28 and 27 respectively.

Figure 5 shows a rear view of a practical construction of the machining station, in which the various items of the support structure housing and other components previously referred to are Identified. Each of the adjustment screws 24 for the bottom guide plate Is provided with a knurled outer end, by which manual adjustment of the screw position may readily be carried out. When adjustment of the screws 24 is complete, they are locked in position by a lock-nut 54 in each case. The top cover 25 Is bolted to the end walls 26 and to the front and rear walls of the housing structure by set-screws 29. Each front and rear wall of the housing has a portion 30, which Is removable for convenience In assembly and replacement of milling cutters. An Input shaft 31 1s connectable to a drive shaft of the apparatus as a whole, and the lower milling cutters 16c and 16d are mounted on this shaft. Spur-gear 32 on this shaft transfers the drive through further spur-gears 33 and 34 to a top shaft spur-gear 36. The upper milling cutters 16a and 16b are mounted on this top shaft. In this drawing also, the guide plate adjusting screws 36 for the top guide plate are shown in dotted outline.

The various components already discussed are shown further In the bottom view of Figure 6 which thus needs no further detailed description. The arrangement by which the bottom guide plate 18 Is moved towards and away from the path of travel of the elongate section 9 will be further apparent from Figure 6 and the arrangement is also shown plctorlally In Figure 7. This Figure depicts a portion of an end wall 26, with the slot or groove 23 which accommodates an end edge surface of the guide plate 18 extending at right angles to the guide surface of the plate which abuts the section 9. The adjustable screw 24 with its tapered inner end is shown extending through a tapped hole in the wall of the housing, and it will be seen that by screwing Item 24 in and out of the hole In the wall 26, the point of contact between a lower corner of the guide plate 18 and the conical surface 55 of the screw may be varied. In this way the plate may be pushed towards or allowed to move away from the path of advance -10of the elongate section to be machined and the restraining or guiding * force applied to the advancing section by the plate may also be varied.

* Figure 8 shows the arrangement by which adjustment of the guide plates 17, 19 and 20 Is achieved. The arrangement shows the adjustment for one end of plate 20, but similar arrangements apply at Its other end and at the respective ends of the other guide plates in question. The displaceable guide mount 21 is slidably received in a hole 37 extending through the wall 28 of the machining station housing structure. This slideable mount is Itself provided with a tapped hole 38 into which a screw 36 is inserted. The screw 36 is held in the region of its headed end by a washer 40, which engages under the head of the screw 36 and is held against the outer surface of wall 28 by cover 22. Cover 22 is screwed to wall 28 by set-screws 39. It will be-seen that by the engagement of the head of screw 36 between cover 22 and washer 40, screw 36 is held against axial displacement.

However this engagement of its head is not sufficient to prevent rotational displacement of the screw and such rotational displacement will accordingly result in axial displacement of guide mount 21, since the screw 36 is itself axially restrained. Screw 36 is provided with an Alien head and access for adjustment is provided through a central hole 41 in cover 22. Each of the guide plates in question may be individually adjusted in position at each end, so as to control not only the spacing between opposed pairs of the guide surfaces substantially surrounding the path of advance of the elongate section but also the parallelism of these surfaces relative to that path of advance in the direction of advance.

Figure 9 is an end view of the machining station from the downstream end. In addition to items identified in connection with the previous drawings, there is shown the hole 42 through which the section to be machined leaves the machining station of the apparatus. Figure 10 Is a sectional view showing the Internal arrangements within the housing structure of the machining station for accommodating the milling cutters and driving them. The top shaft 43 is shown and also roller > 35 bearings 44 by means of which the top and bottom shafts are * -11accommodated In the housing structure In a rotatable manner. lhe Fixing ot the milling cutters to these shafts Is carried out in * conventional manner, and the arrangement Includes spacers, ot which spacer 45 fs Indicated. a The embodiment of the apparatus described In relation to the preceding Figures provides for milling slots or recesses In a substantially rectangular elongate section. By suitable adaptation of the guide means and the milling cutter arrangement, sections of other crosssections may also be accommodated and slots may be cut in different parts of the sections, and not merely at the corners of a squaresection length of material. Sections of up to 20 nm x 12 ran may be handled. The guide structure may In some circumstances also be simplified, and Figure 11 shows a channel guide member 46 which Is suitable for use with rectangular or square section elongate members to be machined. The flanges 47 and the web 48 each define on their inner surfaces guide surfaces for engaging or abutting against the sides of the section to be machined. The channel member 46 may be adjusted in position as a single unit in the manner already described, in opposition to a bottom guide plate of the type already described, the bottom guide plate providing a degree of *float as already explained.

In addition to the bar profiling or mechanical extrusion function previously described, the apparatus of the Invention may also be applied to face milling, an example of which Is shown 1n schematic outline In Figure 12. The section 49 Is guided upstream and downstream of the region of machining contact by channel guides 46a and 46b and bottom guide plates 50a and 50b, In this instance the guide surfaces cannot continue through the actual machining region, since machining Is carried out on all four surfaces of the elongate section. Milling cutters 51 and 52 machine the top and bottom surfaces of the section 49 while further cutters may be provided to machine the front face 53 and the rear face. Flat milling Is shown but In a further adaptation end mills may be used. In this Instance the support structure will Include a more complex drive system, involving helical or bevel gears to transfer the drive from the input * -12shaft to the various angled drive shafts for the end face mills. Face milling may also be carried out to produce surfaces which are not necessarily at right angles to each other. In all arrangements, the guide plate positions may be Initially set against a somewhat overmachined test piece which will not foul the cutters during setting up.

Claims (5)

1. Apparatus for machining an elongate section of machineable material, comprising a machining station, drive means for advancing a said elongate section through the machining station to effect machining contact between each of a plurality of cutting tools mounted at the machining station and said elongate section at a plurality of locations disposed around the periphery of the section during advance of the section through the machining station, and guide means for engaging a said advancing elongate section at a plurality of locations disposed around the periphery of the section to substantially prevent displacement of the section in any direction transverse to the direction of advance of the section, at least in the region of said machining contact between the cutting tools and the section.

2. Apparatus according to claim 1, wherein the guide means comprises a plurality of guide surfaces, each of which engages against a portion of the periphery of the elongate section during advance of the section.

3. Apparatus according to claim 2, wherein each guide surface engages slidingly against a portion of the periphery of the elongate section during advance of the section.

4. Apparatus according to claim 2 or claim 3, wherein each guide surface is located at the machining station of the apparatus so that engagement of the guide surface against an advancing elongate section may be effected in or as close as possible to, the region of machining contact between the cutting tools and the elongate section. 6. Apparatus according to any of claims 2 to 4, wherein means are provided for adjusting the disposition of at least one of the guide surfaces relative to the path of advance of elongate sections to be machined, so that sections of different dimensions may be acconmodated In the apparatus. -1410 6. Apparatus according to any of claims 2 to 5, wherein at least one array of four guide surfaces Is provided for guiding an elongate section of square or rectangular cross-section during advance of the elongate section, said four guide surfaces of the or each said array substantially surrounding the path of advance of the elongate section and each said guide surface of a said array being disposed at right angles to guide surfaces defined by edges of two adjacent guide plates of the array, so that each guide surface may apply a restraining or. controlling force to a respective one of the four faces of the elongate section. /. Apparatus according to any of claims 2 to 6, wherein each guide surface is defined by an edge region of a guide plate. H. Apparatus according to any preceding claim, wherein each cutting tool is a milling cutter. 9. Apparatus according to any of claims 2 to 7, wherein each cutting tool is a milling cutter and said machining contact is effected between the cutting tools and an advancing elongate section of square or rectangular cross-section in the regions of the corners of the section to cut out elongate slots or recesses in these corner regions. 10. Apparatus according to claim 9, wherein the guide surfaces extend continuously through said region of machining contact. 11. Apparatus according to any of claims 2 to 7, wherein each cutting tool is a milling cutter and said machining contact is effected between the cutting tools and an advancing elongate section over at least one face of the section. 12. Apparatus according to claim 11, wherein separate guide surfaces are provided upstream and downstream ot said region of machining contact. 13. Apparatus according to any of claims 8 to 12, wherein a support structure for mounting the milling cutters is provided at the -15machining station and the milling cutters are mounted on shafts which are themselves rotatably mounted in said support structure. . 14» Apparatus according to claim 13, wherein the milling cutter shafts are drivingly interconnected by spur or bevel gears. * 15. Apparatus according to claim 14, wherein one of the milling cutter shafts is drivable by motor means of the apparatus. 16. Apparatus according to any preceding claim comprising a frame, wherein the drive means includes a carriage displaceable along the frame in the direction of section advance. 17. Apparatus according to claim lb, wherein the carriage is drivable along the frame by a lead screw or feed shaft. 18. Apparatus according to claim 16 or claim 17, wherein the carriage Is provided with gripping means such as a vice or a chuck for gripping an elongate section to be advanced through the machining station. 19. Apparatus according to any of claims 16 to 18, wherein the carriage is positioned on the frame relative to the machining station so that in use of the apparatus a section to be machined may be pushed through the machining station. 20. Apparatus according to any preceding claim, comprising a main drive motor. 21. A method of machining an elongate section of machineable material In which a said elongate section is advanced through a machining station to effect machining contact between each of a plurality of cutting tools mounted at the machining station and said section at a plurality of locations disposed around the periphery of the section, . and displacement of the section In any direction transverse to its direction of advance is substantially prevented, at least in the region of machining contact between the section and the cutting tools, by guide means engaging the advancing elongate section at a plurality 1 -16of locations disposed around the periphery of the section· 22. Apparatus for machining an elongate section of machineable material substantially as described herein with reference to or as * shown in the accompanying drawings.

5. 23. A method of machining an elongate section of machineable material substantially as described herein with reference to the accompanying drawings.