GB2090777A - Device for truing workpieces, particularly brake liners - Google Patents

Abstract

The device permits the dust particles and chips produced during a turning operation to which the workpiece is subjected to be removed by suction in the immediate vicinity of the cutting point 32. The cutting tool 31 or tool holder 18 is provided, in the immediate vicinity of the cutting edge, with an integrally formed induction aperture 33 communicating with a suction duct 20 leading to suction means. The tool is mounted in a side wall bounding the U-shaped inducting aperture which leads to a closed intermediate duct 25. This is in a radially adjustable, by a micrometer 26, part 24. The tool may have a duct defined between the tool body and a cap. <IMAGE>

Description

SPECIFICATION Device for truing workpieces, particularly brake liners This invention relates to a device for truing workpieces, particularly brake liners.

Where workpieces have to be tured or turned to size, it is frequently desirable to provide for the dust particles and chips produced during the turning operation to be removed by suction. For example, in cases in which it is desired to turn to size brake liners which generally contain asbestos it is absolutely necessary to remove by suction the asbestos dust particles so as to prevent such particles from finding their way into the atmosphere surrounding the truing device. Asbestos dust has been known to be a very severe hazard to health, and machine operators who inhale asbestos particles for a major period of time may develop the occupational disease known as asbestosis.Removal of dust particles and chips by suction makes it possible to simplify the otherwise tedious work of cleaning the truing device and its surroundings; moreover, in view of the absence of dust particles and/or chips at the cutting point continuous unobstructed observation of the cutting zone is possible.

In the German Laid-Open Specification No. 2837 873 there has been disclosed a dust protection device for use with brake liner turning or truing devices; this protection device comprises a dust collecting bell which is adapted to enclose the entire truing device; said bell is provided with dust remov ing means, e.g. a vacuum cleaner, which is adapted to remove chips and dust particles and to collect them by means of a filtering operation. In view of the large volume of the dust collecting bell and of the fact that it is impossible to provide a hermetical seal between the bell and the truing device, such dust protection devices required a very high suction capacity if it is intended actually to remove all dust particles and chips produced during the turning operation.

Attempts have also been made to provide, in the vicinity of the truing tool, a suction line which has the form of a cap adapted to surround the tool. This arrangement results in an increase of the dimensions of the tool so that it is necessary to remove the dust protection cap in cases where it is difficult to obtain access to the cutting zone. Besides, during the period of starting the turning deice at the beginning of the cutting operation, a considerable portion of the dust protection cap in the vicinity of its suction aperture is open towards the atmosphere, the result being that a small part only of the available suction capacity is available for exhausting dust and chips.

Thus, it is impossible with this turning device to ensure that dust and chips are exhausted completely during the entire machining operation.

In view of the foregoing, it is an object of this invention to provide a device for turning workpieces, particularly brake liners, said device comprising suction means adapted to remove the dust and chips produced during a turning operation, said suction means being designed in such a way that dust and chips are effectively removed during the entire turning operation without handling of the turning device being rendered difficult and without limiting its applicability.

According to the invention, this object is attained by the provision of a structure in which the suction aperture comprising suction line leading to the suction means proper is integrated in the tool or tool holder, respectively, in such a way that this line does not constitute a separate additional structional unit.

In many cases, the tool holder resembles a beam, the front end of which has attached or clamped thereto a cutting bit constituting the tool proper.

With such an arrangement it is possible also to turn with the aid of said tool portions of the workpiece which would otherwise be hard to get at.

An arrangement of this kind is particularly employed in combination with brake liner turning devices or flange turning devices so as to make it possible to cause the cutting tool and the tool holder to enter existing cavities of the workpiece. For use in such cases, the tool holder of the invention is formed as a closed hollow section which merges into an open portion having an L-shaped or U-shaped cross section. The cutting bit is disposed within the open U-shaped portion and attached to one of its limbs. In this embodiment of the tool holder the open side of the section constitutes a suction aperture, and the interior of the closed hollow portion is employed as an integrally formed suction line which is adapted to be connected in a suitable manner to the suction means.In cases in which the tool holder is attached, for example, to a turning arm, at least part of such turning arm also defines a cavity which in this area serves the function of a suction duct of which one end is connected to the hollow interior of the U-shaped portion of the tool holder, the other end being connected to the suction means, for example to a flexible conduit.

At least in the vicinity of the cutting tool, the tool holder is arranged to extend parallel to the surface to be turned and at right angles to the direction of turning. Thus, the open side of the U-shaped portion of the tool holder faces the surface to be turned so that the suction aperture is practically located at the point at which dust and chips are produced during a turning operation. The cutting tool is attached to one of the two limbs of the U-shaped portion in such a way that the suction aperture is directed towards the dust particles and chips approaching it.Even at the beginning of the turning operation, i.e. at the time at which the tool bit starts to engage the workpiece, for example brake liners, practically the entire suction aperture is already disposed to face the workpiece, the result being that, during the operation of exhausting dust and chips, the entry of bleed air tending to reduce the suction effect is practically eliminated. It is thus possible with this embodiment of the tool holder effectively to remove dust and chips by suction and to prevent dust and chips from escaping to the environment.

By virture of the structure in which the tool bit, the tool holder and the suction aperture and the duct associated therewith form parts of an integrated unit, the dimensions of the tool holder practically remain unchanged; besides, the structure described ensures that the tool bit is adapted also to attack hard-to-get-at portions of the workpiece, with the result that dust and chips produced during the entire turning operation can be removed in an effective manner.

The invention and further particulars will be described more specifically hereinafter with referenceto a preferred embodiment shown in the drawings, in which: Figure 1 is a fragmentary longitudinal crosssection of a turning tool according to the invention which is adapted to be employed as a tool in combination with a turning device; Figure 2 is a diagrammatic side elevation of a brake liner turning device comprising a tool holder according to the invention, said tool holder being attached to a turning arm; Figure 3 is an enlarged portion of Figure 2 showing the turning arm and the tool holder in longitudinal cross-section; Figure 4 shows a cross-section of the tool holder; and Figure 5shows the tool holder of Figure 3 in a plan view.

Shown in cross-section in Figure 1 is a conventional hook-shaped turning tool 1 having the free end of a hook-shaped portion formed as a cutting edge 2 which attacks a cylindrical workpiece 3 rotating in the direction of arrow P so as to turn the outside diameter, this operation causing dust particles and chips 4 shown diagrammatically to be produced. The downwardly facing surface of the turning tool 1 shown in Figure 1 is provided with a suction aperture 5 which is disposed in the immediate vicinity of the cutting edge 2, said aperture consistuting the entry of a suction duct 6 with which the turning tool is integrally formed.Said suction duct extends through the interior of cutting tool 1 and is formed, for example, by two bores extending at an obtuse angle in relation to one another, these interconnected bores including a bore 61 with which the hookshaped portion of the turning tool is provided and a second bore 62 which extends through the arm portion of turning tool 1. The suction duct 6 leads to suction means not shown in Figure 1. It would also be possible, for the purpose of defining the suction duct, to make tool 1 in two pieces with the hookshaped turning tool 1 being provided with a cap member 11 attached to the under side of the tool with the result that the suction duct 6 would be defined by cutting tool 1 and cap member 11.

During a turning operation the dust and chips 4 produced during such operation are directly drawn into the suction duct through suction aperture 5 and conducted to suction means (not shown) adapted to remove dust and chips from the air drawn in by filter means.

Figure 2 illustrated a truing or turning device which is adapted, for example, to turn brake liners 12 belonging, for example, to a wheel of a truck or lorry.

After the wheel proper has been removed, the stub axle 13 carrying the exposed brake liners has mounted thereon a supporting tube 14 forming part of the turning device, the supporting tube being clamped to the stub axle. The supporting tube 14 carries a rotary frame 15 which is adapted to be driven in rotation about said supporting tube by means of an electric drive motor 16 by way of a drive chain (not shown). In addition, said rotaryframe 15 is adapted to be displaced axially relative to said supporting tube in the direction of double-headed arrow P1. Said rotary frame is provided with a rotary arm 17, the free end of which has attached thereto a tool holder 18 extending towards the brake liners 12.

Also mounted on rotary frame 15 are dust removing means 19 resembling, for example, a vacuum cleaner and connected to the hollow tool holder 18 by means of a flexible tube 20 as diagrammatically shown in Figure 2.

Figure 3 shows the tool holder 18 which is rigidly connected to turning arm 17 in greater detail.

The tool holder 18 is provided with a tube member 21 which is rigidly clamped to rotary arm 17, the longitudinal axis of said tube member extending parallel to the axis of rotation of rotary frame 15. The free end of tube member 21 has mounted thereon the adjacent end of connecting tube 20. The opposite end of tube member 21 is welded to an adjusting tube 22 extending at right angles in relation to the tube member and towards the brake liners 12 to be turned; the duct defined by tube member 21 terminates in a radial bore 23 formed in a slidable adjusting cylinder 24 which is movable in an axial direction within adjusting tube 22. The radial bore 23 is connected to an axially extending bore 25 formed in the adjusting cylinder 24, the free end of bore 25 facing brake liners 12.By means of a micrometer screw 26 shown diagrammatically only in Figure 3, it is possible to adjust the adjusting cylinder 24 along the axis of adjusting tube 22. Secured to the adjacent end of adjusting cylinder 24 in the vincinity of the adjacent end of axial bore 25 is a box-shaped induction piece 27, the longitudinal axis of which extends parallel to the axis of rotation of rotary arm 17. The induction piece 27 is formed as a hollow section of parallelepied shape provided with a closing wall at one end thereof, said section being provided on its side facing adjusting cylinder 24 with an aperture 28 communicating with the axial bore 25 of adjusting cylinder 24.The free end of the closed box-shaped hollow section of induction piece 27 extending past adjusting tube 24 towards the brake liners merges in an open portion of U-shaped cross-section, the open side of this section facing the brake liners 12. One limb of the U-shaped portion is provided with a recess 30 of trapezoidal shape having clamped in position therein a triangular cutting bit 31 having a pointed portion 32 forming the cutting edge extending outwardly from the U-shaped section. It is by means of this cutting edge that a turning operation on brake liners 12 is performed when rotary frame 17 is driven in rotation. The open side of the U-shaped portion of induction piece 27 is also provided with an induction aperture 33 adapted to remove by suction the dust and chips produced during a turning operation.

Induction aperture 33 is disposed in accordance with the direction of rotation of the device in the trajectory of the dust particles and chips. The free end of induction piece 27 is also open in order to be adapted to catch dust particles and chips approaching the device.

As the brake liners are being turned, the dust and chips are drawn into the induction aperture 33 to be conducted through the interior of induction piece 27, the axial bore 25 and the radial bore 23 of adjusting cylinder 24 and further through tube member 21 and connecting tube 20 to said suction means 19 where such material is removed from the aspirated air by means of a filtering action.

Experiments have shown that it is not absolutely necessary to provide a U-shaped cross-section in the area of cutting point 32 of cutting bit 31; in other words, it is possible in many cases also to provide an L-shaped cross-section, i.e. that it is possible in the vicinity of induction aperture 33 to omit the limb 34 of the open cross-section facing the limb 29. With the induction piece formed in this manner, the dust particles and chips produced during a turning operation will again be caught by induction aperture 33 to be drawn into suction means 19 along the path described earlier.

As shown in Figure 4 with broken lines at 35, it is also possible to close the open end of the tool holder. In this case, induction aperture 33 is defined along its entire periphery.

The induction piece 27 may be made in the manner shown in Figure 5 by peforming milling operations on a solid work piece of parallelepiped shape. By means of a milling operation the workpiece is provided with a channel whose shape corresponds to the internal shape of the hollow section described earlier, the bottom of said channel corresponding to the bottom of the induction piece.

At the front end face also the bottom of the channel is removed by a milling operation so as to form the induction aperture 33. During assembly of the device, this milled component is closed by means of a cover plate 36 extending beyond adjusting cylinder 24. Figure 5 shows said milled component 27 with cover plate 36 omitted.

Claims (11)

1. A device for truing or turning workpieces, particularly brake liners, comprising a cutting tool having a cutting edge and held in position by a tool holder and also compising suction means adapted to remove by suction the dust particles and chips produced during a turning operation, characterized in that the cutting tool or tool holder, respectively, are provided, in the immediate vicinity of the cutting edge, with an integrally formed induction aperture which comminicates with a suction duct leading to said suction means.

2. The device claimed in claim 1, characterized in that said induction aperture is disposed in the trajectory of the dust particles and chips produced during a turning operation.

3. A device for truing workpieces, particularly brake liners, comprising a tool holder resembling a beam, to the free end of which there is attached a cutting bit forming the tool and also comprising suction means adapted to remove by suction the dust particles and chips produced during a turning operation, characterized in that said tool holder is formed as a closed hollow section which merges into an open section in the vicinity of the tool bit, that said tool bit is rigidly mounted in the interior of said open section to one limb thereof and that the open side of sad open section constitutes an induction aperture and that the interior of the closed section constitutes an integrally formed suction duct which is connected to said suction means.

4. The device claimed in claim 3, characterized in that said open section of said tool holder has an L-shaped or a U-shaped cross-section.

5. A device as claimed in claim 3 or claim 4, characterized in that the end face of said tool holder having the shape of a section is open in the vicinity of the cutting tool.

6. A device as claimed in claim 3 or claim 4, characterized in that the free end of said tool holder in the shape of a section member is closed in the vicinity of the cutting tool.

7. A device as claimed in any of the preceding claims 3 to 6, characterized in that the hollow section consituting said work holder has a cross-section of rectangular shape, that the upper surface of said tool holder disposed opposite said cutting edge is rigidly secured to the under side of a tube member extending at right angles to said tool holder and that the interior of said hollow section and the bore of said tube member are connected together to form portions of said integrally formed suction duct.

8. A device as claimed in claim 7, characterized in that that portion of said hollow section of said tool holder supporting the cutting tool extends beyond the outer diameter of said tube member.

9. A device as claimed in claim 7 or claim 8, characterized in that the bore of the tube member supporting said tool holder is connected by a duct to said suction means.

10. A device as claimed in claim 9, characterized in that there is connected to the tube member supporting said tool holder another tubular member extending at right angles to said tube member, the bore of said tubular member communicating with the bore of the tube member supporting said tool holder, and that there is connected to said tubular member a connecting line leading to said suction means.

11. A device for truing or turning workpieces, substantially as described herewith with reference to the accompanying drawings.