EP0193313A2

EP0193313A2 - Engraving tool holder

Info

Publication number: EP0193313A2
Application number: EP19860300996
Authority: EP
Inventors: Frank William Green
Original assignee: Versatile Engineering Ltd
Current assignee: Versatile Engineering Ltd
Priority date: 1985-02-28
Filing date: 1986-02-13
Publication date: 1986-09-03
Also published as: GB8603527D0; GB8505174D0; GB2171650A

Abstract

A holder for an engraving tool includes a body (1) having a shank (2) for attachment to the rotatable chuck of an engraving machine and a tool holding member (4) slideable in a bore (3) along an axis transverse to the axis of rotation of the tool holder. The tool holding member (4) has a location (5) for receiving the shank (6a) of an engraving tool (6) locked by set screw (7) and the member (4) is slideable such that the tool can be moved translationally from a position in which it lies along the axis of rotation of the tool holder to a position to one side of said axis, and vice versa. Set screws (9) entering offset recess (8) are provided for retaining the tool (6) in an adjusted position. According to another embodiment, the tool is mounted so that it can be rotated about an axis normal to the axis of rotation of the tool holder.

Description

BACKGROUND OF THE INVENTION

In carrying out an engraving operation the path of travel of the engraving tool is either controlled by the movement of a stylus or follower over a master pattern corresponding-to the shape to be engraved, often through the intermediary of a pantograph mechanism, ortelse the path of the engraving tool may be controlled in accordance with data derived from a data processor. In any case the width of an engraved line so formed depends on the cutting width or tip size of the engraving tool employed. Thus, it is necessary to have a large number of engraving tools available having different tip sizes in order to engrave a wide variety of lines of different widths. This in turn necessitates frequent changes of engraving tool.
Also, it is frequently a matter of trial and error in order to obtain an engraved line of a particular thickness so as to produce a desired aesthetic effect, for example of a letter or other character being engraved. In practice an engraver may initially produce a thinner line and then in order to produce the final thickness, the engraving tool is either changed or else is reground to produce a thicker line. In the latter event, regrinding of the tool is time consuming and expensive. Not only does frequent regrinding wear away the tool rapidly, but if the regrinding is overdone, too thick a line may be produced which causes wastage of the workpiece as well as requiring another tool to be ground to the desired width.
It is an object of the present invention to provide an engraving tool holder which enables the aforementioned disadvantages to be alleviated or overcome.

SUMMARY OF THE INVENTION

From one aspect of the invention provides a holder for an engraving tool including a body having means for attachment to the rotatable drive of an engraving machine and a tool holding member displaceable relative to the body such that an engraving tool carried thereby can be moved between a position in which the cutting tip of the tool lies on the axis of rotation of the tool holder to a position in which the cutting tip of the tool is displaced from said axis of rotation of the tool holder.
In one form of the invention, the tool is arranged for translational displacement relative to the axis of rotation of the tool holder.
Thus, from another aspect the invention provides a holder for an engraving tool including a body having means for attachment to the rotatable drive of an engraving machine and a tool holding member slideable along an axis transverse to the axis of rotation of the tool holder, said tool holding member having a location for receiving the shank of an engraving tool and being slideable such that the tool can be moved translationally from a position in which it lies along the axis of rotation of the tool holder to a position to one side of said axis, and vice versa, and means for retaining the tool in an adjusted position.
According to another form of the invention, the tool is mounted so that it can be rotated about an axis normal to the axis of rotation of the tool holder.
The invention therefore also provides a holder for an engraving tool including a body having means for attachment to the rotatable drive of an engraving machine and a bore receiving a tool holding member rotatable through an angle about an axis normal to the axis of rotation of the tool holder, said tool holding member having a location for receiving the shank of an engraving tool such that by rotation of the tool holding member, the tool can either be caused to lie along the axis of rotation of the tool holder or at an angle thereto, and means for retaining the tool in an adjusted position.
The body of the holder is preferably provided with a shank to fit in the chuck of an engraving machine.
The means for retaining the tool in an adjusted position may comprise two set screws arranged at diametrically opposite sides of the tool and engageable with the shank of the tool. By appropriate advancing and retraction of the two set screws, the shank of the tool and hence its tip can be displaced towards and away from the axis of rotation of the tool holder and maintained in any desired position within the possible range of movement. A further set screw may be provided for securing the shank of the tool relative to the tool holding member.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:-

Figure 1 is a side view of one embodiment of engraving tool holder according to the invention,
Figure 2 is a side view at right angles to the view in Figure 1,
Figure 3 is a section on the line III-III in Figure 1,
Figure 4 is a side view of a further embodiment of engraving tool holder according to the invention,
Figure 5 is a partial sectional view through the tool of Figure 4; and
Figure 6 is an underneath plan view of the tool holder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to Figures 1 to 3, the engraving tool holder shown in this embodiment is intended to permit translational displacement of an engraving tool relative to the axis of rotation of the tool holder. The device comprises a cylindrical body 1 having a shank 2 for fitting in the chuck of an engraving machine. The body 1 is provided with a cylindrical diametric bore 3 adjacent its lower end in which can slide with a close fit a correspondingly shaped cylindrical bar 4, forming a tool.holding member, having a bore 5 for locating the shank 6a of an engraving tool 6. A set screw 7 located in a threaded axial passage in the bar 4 is provided for locking the tool 6 in position in the bore 5. The upper end 6b of the shank of the tool 6 extends beyond the bar 4 and is accommodated in an elongated offset recess 8 in the body 1. Two diametrically spaced set screws 9 are located in threaded bores provided in the body 1 above the bore 3 but parallel thereto, such that the set screws can engage the upper end 6b of the shank of the tool 6.
As will be apparent, by appropriate advancing and retraction of the set screws 9, the shank 6b of the tool 6 can be moved between a position in which the tip of the tool lies on the axis of rotation of the tool holder and any of many positions in which the tip-of the tool 6 is translationally displaced from this axis, within the range of adjustment permitted by the length of the elliptical recess 8. The tool holding member 4 obviously slides to and fro in the bore 3 as the shank 6b of the tool is moved by the set screws 9. The set screws also serve to lock the tool 6 in an adjusted position.
Referring now to the embodiment of Figures 4 to 6, the engraving tool holder shown in this embodiment is intended to permit rotation of the tool about a horizontal axis normal to the vertical axis of rotation of the tool holder. The device comprises a cylindrical body 11 having a shank 12 for fitting in the chuck of an engraving machine. The body is provided with a diametrically extending cylindrical bore 13 which receives a corresponding dimensioned cylindrical tool holding member 14 having a cross hole 15 to receive the shank 16a of an engraving tool 16. The tool shank is held in position in the hole 15 by a set screw 17 extending axially of the cylindrical member 14. The tool 16 extends through an appropriately aligned elongated aperture 18 in the lower end of the tool holder 11 so that rotation of the cylindrical tool holding member 14 about its axis causes the tip of the tool 16 to move between a position along the axis of rotation of the tool holder (shown in full lines in Figure 4) and any of many positions displaced from this axis (as shown in broken lines in Figure 4), within the range of adjustment permitted by the elongated aperture 18. This adjustment is achieved by means of two diametrically spaced set screws 19 located in threaded bores in the body 11 below the bore 13 and at right angles thereto. These set screws are respectively retracted and advanced until the tip of the tool 16 is at the desired position and.are then locked against the shank of the tool to hold it in the adjusted position.
As will be apparent with the arrangement of the present invention, when the tip of the tool is displaced from the axis of rotation of the tool holder the tip of the tool will describe a circular locus which consequently increases the width of the groove cut in a workpiece to be engraved, the magnitude of this increase in width being dependent on the amount of displacement of the tool tip from the axis of rotation of the tool holder.
Clearly the range of adjustment of the width of cut is limited for any one size of tool holder and therefore different sizes of tool holder may be provided each of which covers a substantilly different range of widths of cut.
The tool holder according to the present invention provides in particular the following advantages:-

1. A smaller number of tools than hitherto are needed to cope with the variety of engraving demanded.
2. It is no longer always necessary to change the engraving tool to produce engraving of different widths.
3. It is a simple matter to adjust the thickness of an engraved line to produce the desired aesthetic effect and frequent regrinding of tools is avoided.
4. When cutting holes through material the diameter of the holes can be adjusted within limits thus avoiding the necessity of having a large number of templates and avoiding the necessity to have engraving tools for this purpose made accurately.

Claims

1. A holder for an engraving tool characterised in that it includes a body (1,11) having means'(2,12) for attachment to the rotatable drive of an engraving machine and a tool holding member (4,14) displaceable relative to the body such that an engraving tool (6,16) carried thereby can be moved between a position in which the cutting tip of the tool lies on the axis of rotation of the tool holder to a position in which the cutting tip of the tool is displaced from said axis of rotation of the tool holder and means (9,19) for retaining the tool in an adjusted position.

2. A tool holder as claimed in claim 1, characterised in that the tool (6) is arranged for translational displacement relative to the axis of rotation of the tool holder.

3. A tool holder as claimed in claim 2, characterised in that the tool holding member (4) is slideable along an axis transverse to the axis of rotation of the tool holder (1), said tool holding member having a location (5) for receiving the shank (6a) of an engraving tool (6) and being slideable such that the tool (6) can be moved translationally from a position in which it lies along the axis of rotation of the tool holder (1) to a position to one side of said axis, and vice versa, and means (9) for retaining the tool in an adjusted position. :

4. A tool holder as claimed in claim 1, characterised in that the tool (16) is mounted so that it can be rotated about an axis normal to the axis of rotation of the tool holder. ;

5. A tool holder as claimed in claim 4, characterised in that the body (1) has a bore (13) receiving a tool holding member (14) rotatable through an angle about an axis normal to the axis of rotation of the tool holder (1), said tool holding member (14) having a location (15) for receiving the shank (16a) of an engraving tool (16) such that by rotation of the tool holding member (14), the tool (16) can"either be caused to lie along the axis of rotation of the tool holder or at an angle;thereto, and means for retaining the tool in an adjusted position.

6. A tool holder as claimed in any preceding claim, characterised in that the body (1,11) of the holder is provided with a shank (2,12) to fit in the chuck of an engraving machine.

7. A tool holder as claimed in any preceding claim, characterised in that the means for retaining the tool (6,16) in an adjusted position comprises two set screws (9,19) arranged at diametrically opposite sides of the tool and engageable with the shank of the tool, so that by appropriate advancing and retraction of the two set screws, the shank (6a,16a) of the tool and hence its tip can be displaced towards and away from the axis of rotation of the tool holder and maintained in any desired position within the possible range of movement.

8. A tool holder as claimed in any preceding claim, characterised in that it includes a set screw (7,17) for securing the shank of the tool relative to the tool holding member.

9. A tool holder as claimed in any preceding claim, in which the tool holding member (4,14), is cylindrical and is a close fit in a cylindrical bore (3,13).