GB2081615A - A profile machine for wood-cutters - Google Patents

Abstract

A profile grinding machine for wood cutters 44 has a stylus 24 for co-operation with a template 22 carried by a freely movable table 16. The stylus in itself is mounted on an adjustable bracket 25 which can be rocked to effect radial adjustment of the stylus and moved axially to effect axial adjustment of the stylus. A single spring 70 acts in torsion and compression on the bracket to absorb backlash in both adjustments. <IMAGE>

Description

SPECIFICATION A profile machine for wood-cutters A profile grinding machine for forming shaped profiles on cutters for use in woodshaping machines, such as shapers and spindle moulders, is described in the Specification of Patent Application No: 8026301. In such a machine, there is a table free to move both axially and radially relatively to the grinding wheel axis, the table carrying a cutter support and a template. In use, the template is pressed against a stationary stylus, and the table moved axially whilst maintaining the template in contact with the stylus. This causes the table to traverse a path which is a reverse trace of the template profile, and this in turn causes the template profile to be reproduced by the grinding wheel in a cutter blank carried by the cutter support.

It is desirable to provide for very accurate and consistent location of the stylus on the machine to ensure that the correct profile is produced on the cutter, but is is also preferable to provide for easily effected adjustment of the stylus both axially and radially with respect to the grinding wheel axis (i.e.

in the same senses that the table is free to move).

Axial adjustment of the stylus is required to maintain the correct relationship between the cutter blank and the grinding wheel as material is ground off the sides of projections on the cutter profile. These desiderata of ease of adjustment and consistent location can be opposed to each other, but the present invention provides an arrangement in which they are both ensured.

According to this invention a profile grinding machine for wood cutters comprises a grinding wheel mounting including a spindle, a stylus carried by an adjustable bracket; a table free to move axially and radially relatively to the spindle the table having a mounting for a template which is engageable with the stylus and a mounting for a cutter blank to be profile ground in accordance with a pattern produced by the interaction of the template and the stylus; means for effecting displacement of the adjustable bracket in a direction parallel with the spindle axis to effect axial adjustment of the stylus; means for rocking the adjustable bracket about an axis parallel with the spindle axis to effect substantially radial adjustment of the stylus and single spring means opposing in one direction of each motion both said axial displacement and said rocking of the adjustable bracket to take up any backlash in the displacement and rocking means.

Preferably the single spring means comprises a combined torsion and compression spring, the torsion characteristic being used to take up backlash in the rocking means and the compression characteristic being used to take up backlash in the axial displacement means. Preferably both the rocking means and the axial displacement means are screw-and-nut devices.

In the preferred construction, the adjustable bracket has a boss rotatable on a mounting shaft, a screw-threaded nut device for moving the boss axially on the mounting shaft, the spring acting axially between the boss and a fixed abutment, to urge the boss towards the nut device, there being an arm extending radially from the boss with a screwthreaded spindle engaging in a screw-threaded hole in the arm, one end of this spindle being engageable with a fixed anvil on the machine and the spring urging the boss angularly to press the spindle into engagement with the anvil. It is further preferred that the stylus is removable from the adjustable bracket, there being a locking screw for holding it in position.

The construction of a profile grinding machine for wood cutters in accordance with the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of part of the machine, Figure 2 is a plan view of the parts shown in Figure 1, Figure 3 is an end view of the parts shown in Figure 1, and Figure 4 is a partly sectioned detail view.

Although only certain parts of the machine are illustrated in the drawings, sufficient has been shown to describe the present invention, without unnecessary detail. The machine has a grinding wheel mounting, which includes the usual spindle (not visible in the drawings) and grinding wheel adapters. The grinding wheel itself is shown at 10, and the customary grinding wheel guard is shown at 12. It will be appreciated that the machine is equipped with an electric motor and belt drive (not shown) for the grinding wheel. For present purposes, the location of the grinding wheel spindle can be considered as stationary and the spindle axis is indicated at 'X' in Figure 3.

Part of the machine bed is shown at 14, and a table 16 is provided, which is free to move within limits both axially and radially with respect to the spindle axis (i.e. the direction indicated by the arrows 'A' and 'B' in Figures 1 and 2). It is important that the table mounting arrangement is such that the table is quite free to move in the directions indicated, so that it can also make movements which are compounds of the two indicated freedoms. The table is not required to move vertically.

A clamp 18 is provided on the table 16, and as shown in Figures 1 and 2 a metal template 20 can be secured to the table 16 by the clamp 18 with a profile formed edge 22 of the template facing the grinding wheel spindle. The shape of the edge 22 determines the shape of the profile which will be ground on the cutter and hence it also determines the shape which will be moulded by that cutter in the timber during a woodshaping operation. If the geometry of the profile grinding machine is correct, the shape of the template profile 22 can be the precise reverse of the shape required in the finished timber mould. It will be appreciated that various templates 20 can be used with the machine and these are changed as The drawing(s) originally filed was/were informal and the print here reproduced is taken from a later filed formal copy.

required when cutters for different moulds are needed. Besides the clamp 18, there are also locations (not shown) for ensuring that the various templates are located in correct relationship to the table 16.

The machine also has a stylus 24 carried by an adjustable stylus bracket 25 which allows the position of the stylus relatively to the grinding wheel spindle to be pre-selected.

It will be appreciated that it is possible to manipulate the table 16 to bring the profile edge 22 of the template into engagement with the stylus 24, and if one end of the profile edge is so engaged and then the table moved axially (direction of arrowA) whilst maintaining pressure on the table towards the grinding wheel spindle (direction of the arrow B1 the compound path of movement of the table relatively to the grinding wheel 10 is a reverse trace of the profile edge 22.

A support bracket 26 on the table 16 included a journal mounting 28 for a cutter support shaft 30 which is thus rotatable about an axis parallel with the spindle axis 'X'. At the right hand end (from the point-of-view of the operative) the shaft 30 is fitted with a handwheel 32 and at its left hand end it is fitted with a cutter support block 34. The latter is a metal block of quadrilateral cross-section (see especially Figures 1 and 3) but it is a significant feature of the block 34, that the perpendicular distances between the four faces 36,38,40 and 42 and the shaft axis are different from each other.

The method by which the shape of the block 34 is used to influence the cutting angle is described in detail in the Specification of Patent Application No: 8026301.

Each of the faces 36,38,40 and 42 is adapted to provide support for a cutter blank, one of which is shown at 44, and a releaseable clamp plate 46 is provided which can be secured to any one of the faces 36,38,40 and 42 to clamp a cutter blank to the block 34 as shown. The clamp plate is adapted to locate the blanks in the same forward and rearward location on the machine, irrespective of which of the faces of the block is brought to the operative position and fitted with the cutter blank and the clamp plate.

Finallythe machine is equipped with a cutter guide plate 48 secured to a column 50 on the machine, the top edge of the guide plate 48 providing a location edge as will appear. The column 50 serves another purpose which is described in the Specification of Patent Application No: 8026290 but for present purposes, the plate 48 can be regarded as stationary.

The purpose of the location edge of the plate 48 is to support the rear portion of the cutter 44 and it will be noted that the location edge lies very close to the periphery of the grinding wheel, where the cutter blank should engage with the grinding wheel. In most instances, as illustrated in Figure 2, this location will be below the horizontal plane passing through the spindle axis 'X'. As the grinding wheel wears, it is fed towards the location edge which con sequently remains a datum position on the machine.

When a cutter profile is to be formed, the required template 20 is clamped on the table 16 and the block 34 is rotated to bring the face 36,38,40 or 42 associated with the required cutting angle to the operative (top) position. The blank 44 is then clamped to the operative face of the support block and then that block is turned until the blank 44 also rests on the location edge of the plate 48. It is possible to hold the blank .n engagement with the location edge by pressure applied through the handwheel 32, and at the same time, the table 16 can be pressed rearwardly to bring its template into engagement with the stylus and then axially so that it follows the reverse template trace as previously described. During this motion, the grinding wheel 10 will grind the required profile on the blank 44.

Now it will be appreciated that the position of the stylus 24 must be accurately pre-selected before grinding can commence and to this end, the bracket 25 is adjustable both axially (arrow A) and radially (arrow B) with respect to the spindle axis X. The bracket 25 has a boss 60 which is free to rotate and slide on part of a mounting shaft 62. (See Figure 4).

The latter has a short screw-threaded portion 65 which engages in a screw-threaded bore in a boss 64 which is rigid with the bed 14 of the machine. A collar 61 is also secured to the boss 64 by a pin 67. At the left hand end of the mounting shaft, there is a screwed rod 63 screwed tightly into the shaft and projecting therefrom. A washer 66 is fitted on the projecting portion of the rod 63 and engages with the left hand end of the boss 60, and an internally screwed knob 68 also engages on the rod 63. Finally, a combined torsion and compression helical spring 70 is fitted around the shaft 62 one end engaging with the bracket 25 and the other end engaging in a hole in the collar 61. The compressive characteristic of this spring 70 urges the boss 60 to the left, so that in practice, the knob 68, washer 66 and boss 60 are all pressed axially together.

The bracket 25 has a swan-necked arm 71 integral with the boss 60 and terminating at the front upper end in a small boss 72 bored vertically to receive the stylus 24. A locking screw 74 is provided for securing the stylus in the boss 72, so that by slackening the locking screw 74, it is possible to release the stylus, to allow a new stylus to be fitted.

At its lower rear end the arm 71 has another small boss 76, having a vertical screw-threaded bore in which there is engaged an adjusting screw 78 formed with a knob 80. Gravity will normally cause' the lower end of the adjusting screw 78 to rest on an anvil 82 fixed to the machine bed, but the torsion characteristic of the spring 70 resists clockwise motion of the bracket 25 about the shaft 62 - that is to say, the torsion effect of the spring tends to urge the screw 78 into engagement with the anvil 82.

If it is required to adjust the position of the stylus axially, this can be done by turning the knob 68, thus moving the boss 60 along the shaft 62. The boss 60 will remain firmly held against the collar 66 and any backlash in the screw-and-nut connection will be taken up by the compressive characteristic of the spring 70. Thus the construction assures the consistent location of the stylus axially.

If it is required to adjust the position of the stylus radially, then the knob 80 is turned: by virtue of the screw-and-nut effect between the adjusting screw 78 and the boss 76 and the engagement of the screw with the anvil 82, this causes the bracket 25 to turn about the shaft 62. As a result, the stylus moves forwardly or rearwardly (i.e. radially of the grinding wheel spindle). The actual movement of the stylus is in an arc about the axis of the shaft 62, but as the permitted forward and rearward motion is quite small, it provides substantially linear adjustment of the stylus position. The torsion effect of the spring 70 ensures the consistent location of the stylus radially by taking up any backlash in the adjusting screw 78 and by holding that screw firmly in engagement with the anvil 82.

It will be appreciated therefore that the simple mounting arrangementforthe stylus permits all the adjustment which is necessary and firmly holds the stylus in any selection position.

Claims (6)

1. A profile grinding machine for wood cutters comprising a grinding wheel mounting including a spindle, a stylus carried by an adjustable bracket; a table free to move axially and radially relatively to the spindle the table having a mounting for a template which is engageable with the stylus and a mounting for a cutter blank to be profile ground in accordance with a pattern produced by the interaction of the template and the stylus; means for effecting displacement of the adjustable bracket in a direction parallel with the spindle axis to effect axial adjustment of the stylus; means for rocking the adjustable bracket about an axis parallel with the spindle axis to effect substantially radial adjustment of the stylus and single spring means opposing in one direction of each motion both said axial displacement and said rocking of the adjustable bracket to take up any backlash in the displacement and rocking means.

2. A profile grinding machine as claimed in Claim 1, in which the single spring means comprises a combined torsion and compression spring, the torsion characteristic being used to take up backlash in the rocking means and the compression characteristic being used to take up backlash in the axial displacement means.

3. A profile grinding machine as claimed in Claim 1 or Claim 2, in which both the rocking means and the axial displacement means are screw-and-nut devices.

4. A profile grinding machine as claimed in any one of Claims 1 to 3, in which the adjustable bracket has a boss rotatable on a mounting shaft, a screwthreaded nut device for moving the boss axially on the mounting shaft, the spring acting axially between the boss and a fixed abutment, to urge the boss towards the nut device, there being an arm extending radially from the boss with a screwthreaded spindle engaging in a screw-threaded hole in the arm, one end of this spindle being engageable with a fixed anvil on the machine and the spring urging the boss angularly to press the spindle into engagement with the anvil.

5. A profile grinding machine as claimed in any one of Claims 1 to 4, in which the stylus is removable from the adjustable bracket, there being a locking screw for holding it in position.

6. A profile grinding machine for wood cutters constructed and arranged substantially as herein described with reference to the accompanying drawings.