GB2238743A - Milling machine - Google Patents

Abstract

Apparatus for milling at least two surfaces of an elongate workpiece comprises a base 21 having a longitudinal axis along which the workpiece moves, in use, and carrying adjustable retaining moans whereby the workpiece can be vertically and laterally, but not axially, retained in position relative to the base, a milling head frame 28 movable vertically and laterally relative to the base 21, one or more motors for effecting each degree of movement of the frame relative to the base, and at least two milling heads 29 preferably four rotatably mounted on the frame each for carrying a milling cutter facing towards the workpiece surfaces with one or more milling head motors. The retaining means are vertically and horizontally spaced rollers 26, 27, there being two sets of two such pairs; between the sets is the frame 28. The workpiece is moved back and forth axially by a clamp 13, 17 operated by a cylinder 11, with repeated passes for sequential milling of the respective surfaces, the frame being adjusted between operations. A cut-off saw is provided. <IMAGE>

Description

MILLING MACHINE Background to the Invention The invention relates to milling machines and is specifically concerned with machines which are capable of milling work pieces with at least two perpendicular surfaces to be milled.

Such work pieces are exemplified by the elongate metal box section channels used in the double-glazing industry for forming window and door frames. Slots and grooves have to be milled out of the mutually perpendicular surfaces of such work pieces, and a number of machines have been designed to do this.

Conventional milling machines for such use are often designed to mill one surface at a time by following a template showing the required shape of slot. Once one surface has been milled, the work piece has to be moved to a different position in order that the machine can follow the same or another template and mill the next surface.

In between positioning and clamping the work piece, and changing the template if necessary, milling has to stop. Other machines have therefore been designed to perform several milling operations simultaneously on two or more surfaces of a box-section channel, in which the work piece need not be moved but, once clamped in position, is operated on by several milling heads in succession. The applicant's own UK patent specification No 2 177 634 describes and illustrates one such machine.

The construction of this latter kind of machine is, however, relatively complex mechanically.

There is therefore a need for a milling machine which will deal satisfactorily with the kind of elongate box-section channel under discussion but which combines the best features of the conventional non-moving-head machine, first reviewed above, with the advantages of the multi-head machine exemplified by the applicant's machine of specification 2 177 634.

Summary of the Invention The scope of the invention will be defined in the subsequent claims. But one machine embodying the invention is shown in the drawings accompanying this specification. It will now be described with reference to those drawings.

Brief description of the Drawings All the drawings are diagramatic, only, for clarity and in order to concentrate on showing the working principles of the machine rather than unnecessary detail which the skilled addressee of this specification will readily provide himself without the need for further inventive thought. Figures 1 to 4 are drawn to approximately the same scale; figure 1A is drawn to a much larger scale.

Figure 1 shows the main functional sequence of the machine in perspective; Figure 2 shows a central part of the machine viewed in side elevation; Figure 3 shows another part of the machine, this time viewed in end elevation with respect to figures 1 and 2; Figure 4 shows a part of the machine already shown diagramatically in figure 2, viewed in the same sense as figure 1; and Figure 1A is a scrap view showing part of the machine when viewed in plan with respect to figures 1 to 4.

Description of the Preferred Embodiment The milling machine illustrated is designed to mill, cut to length, and eject a succession of parts from an elongate work piece such as the aluminium rectangular-section box channels used in the double-glazing industry. It can handle other work pieces and it is not restricted to handling work pieces of the specific class just described. It can mill all four surfaces of a rectangular-section work piece, but it mills them in sequence rather than simultaneously.

The machine handles its work piece in essentially five consecutive movements. First, the work piece is gripped and advanced to be positioned in the milling zone. Second, rollers clamp all four surfaces of the work piece. Third the work piece is milled sequencially on as many faces as are necessary whilst it remains clamped between the rollers, and is moved back and forth as needs be. Fourth, the now-milled piece is parted from the main body of the work piece. Fifth, and finally, the parted-off piece is ejected from the machine.

The way the machine achieves this sequence of operations will now be set out with reference to the drawings.

A double-acting pneumatic actuator 11 pulls an arm 12 back and forth along a linear path on command from the electronic circuitry which controls the whole machine. The arm 12 moves a U-arm 13 about a pivot 14 (figure 1A) and the remote end 15 of the U-arm 13 functions as a jaw clamping against one face of an elongate box-section channel work piece 16.

The opposite face of the work piece 16 is trapped by the clamping action of the jaw 15 against a fixed back-jaw 17.

All the components 11 to 17 described so far are mounted on a travelling carriage 18 which is moved by a chain drive 19 along a work table 21.

The chain drive 19, only part of which is shown in the drawings, forms with the carriage 18 and its associated components an assembly which is known technically as a linear actuator beam. It enables the work piece 16, securely gripped between the faces of the jaws 15 and 17, to be advanced and retracted towards and away from the milling-head-zone 22 of the machine.

Freely rotatable rollers 23 succeed one another along the path of travel of the work piece 16 towards the milling zone 22. They are shown grooved in figure 1 to allow the backjaw 17 to pass. Freely rotatable horizontally-mounted rollers 24 protrude through slots (not shown) in the surface of table 21 to give the underside of the work piece 16 smooth passage.

No more detail of these roller-sets need be supplied.

As the work piece 16 is advanced by a linear actuator beam assembly into the milling-head zone 22 of the machine, its underside passes over two successive freely rotatable horizontally mounted rollers 25. Its top face passes under two similarly horizontally mounted successive freely rotatable rollers 26.

And its opposite upright side surfaces pass between respective pairs 27 of freely rotatable vertically mounted rollers.

All these rollers 25, 26, 27 are faced with a suitably hard but replaceable material such as polyurethane. They all circular-cylindrical in form. As the minor arrows in the zone 22 of figure 1 show, as well as rotating about their individual axes, they can all move up and down (in the case of rollers 25 and 26) or from side to side (rollers 27) so that, when appropriately positioned, between them they clamp all four faces of the box-section work piece 16 rigidly within the milling-head zone 22.

The means to move the rollers up and down can be supplied by the skilled addressee of this specification. Suffice it to say that pneumatic actuators, for example, could do the job.

The gap between the two successive roller sets 25, 26, 27 (successive in the context of the advancement of the work piece 16 in the direction of arrow A) is large enough to accomodate the milling head itself. But with that proviso satisfied, the gap is kept as short as possible, to give maximum rigidity of clamping from the action of rollers 25, 26, 27.

For the same reason, as just mentioned, the actual milling head is between the two successive roller sets so that the work piece 16 is, during milling, clamped rigidly on either side of the milling head; and clamped as close to the milling head, on each side thereof, as is reasonably possible.

The milling head comprises an essentially rectangular rigid frame 28 carrying four milling-cutter motors 29. The four motors 29 are mounted at right angles to one another as figure 4 shows. Each of them carries appropriate milling cutters.

The head 28 and its motors 29 have deliberately not been shown in figure 1, which would otherwise be too crowded for clarity. But the head 28 is shown in figure 2. Also shown in figure 2, diagramatically, is the fact that the milling head frame 28 - which is cross-hatched - moves independently of the frame - shown diagramatically as 29, and double-hatched - which carries the two successive roller sets 25, 26, 27.

Referring back to figure 4, the milling head frame 28 and its motors 29 are movable in respective up and down (arrow Y) and side to side (arrow X) directions, by screw drives indicated generally at 31 and 32 respectively. The main frame on which the whole machine is built, deliberately not shown in any of the drawings, accommodates milling head 28, 29 for such movement independently of the individual clamping movements of roller sets 25, 26, 27 and the illustrated "frame" 29 of figure 2 is, as mentioned, purely intended to illustrate this fact and not to be representative of any actual construction that might be adopted to position and support these work piece clamping roller sets.

The Y-axis movement of milling head 28, 29 is cushioned by an actuator 33 which is connected at one end to frame 28 and at its other end to the non-moving main frame of the machine. The means by which the screw drives 31 and 32, and the individual milling heads 29, are driven can again supplied from known alternatives by the skilled reader.

Immediately after the second work piece-clamping roller set 25, 26, 27 a circular saw 34 is positioned. The circular toothed saw blade 34 rotates about its own axis, as indicated by symbol R, and can swing in an arc in, broadly speaking, the Y-axis of the moving milling head 28, 29. Figure 3 shows the construction of saw 34 in detail, from which it will be seen that an arm 35 mounts the saw blade 34 at one end and at its other end is pivoted to the non-moving main frame of the machine. The drive motor 36 and belt 37 that rotate blade 34 are shown in figure 3, motor 36 being mounted on and moving with the arcuate travel of arm 35.

Also shown in figure 3 is another actuator 38 mounted at one end to arm 35 and at its other end to the non-moving main frame of the machine. Actuator 38 governs the arcuate movement of arm 35 and, in this particular instance, is an oil-filled actuator; but the oil is pumped to the actuator via pneumatic cushioning reservoirs (not shown).

Just as saw 34 is as closely as possible adjacent the last roller 27 of the second of the two succe,ssive roller sets 25, 26, 27 so piston-and-cylinder unit 39 is mounted as closely as possible after saw 34. The line of action of this linearaction unit is parallel to the X-axis movement of the milling head and the unit is so positioned that it acts to eject, sideways, from the machine the finish-milled components that have been parted from the main work piece by saw 34.

In use, and with work piece 16 spanning the gap between the two work piece-clamping roller sets 25, 26, 27 and clamped rigidly by both of them as well as by jaws 15 and 17, milling heads 29 are moved successively to work on a respective face of the work piece. The linear actuator beam 18 etc.

advances and retracts work piece 16, work piece-clamping 25, 26, 27 successively release and clamp the work piece to allow this to happen, and milling head unit 28, 29 is moved along its respective X and Y axis, all under the command of the circuitry that guides the machine and all so as to produce the required holes, grooves and slots in the four work piece surfaces.

This mode of action contrasts with that of the machine previously described and illustrated in the applicant's own UK patent specification No 2 177 634 where the various milling heads can, to an extent move independently of one another but the work piece, once in position, cannot move in the way that this one can. When all the milling has been finished, work piece 16 is advanced for one last time by unit 18 etc.

clamped by rollers 25, 26, and 27; sawn by saw 34 springing downwards on its arm 35 to part the finished work piece from the rest of the channel; and eject it sideways by unit 39.

There follows a list of suppliers of the individual components within the United Kingdom, for a machine embodying the principles illustrated in the drawings and described in this specification. This is of course by way of example only and is not to be taken as limiting the scope of the invention, which will be defined in the claims.

List of Suppliers Cetronic Dynamics Limited Hbddesdon, IIerts Drive Electronics Anglair, Norwich Pneumatic Fittings We Sge, Norwich Electric Motors Unimatic, London Linear Beatings A.H. Webber,.

Gt. Yarmouth Roller Bearings R. s. Components, Corby Computer and control gear btsoutter London Pneumatic Spindles Crocus, Stockport Linear Actuator B.R.T Bearings Ct. Yarmouth Multi v drive Belts Comtel, Great Yarmouth Monitor Blackburns, Norwich Aluminium Stock Norfolk Steel Kings Lynn Steel suppliers Kingston Engineering 1l Leadscrew Strongbar, Aylsham Hardened linear shaft Anglia Plastics Thetford Tufnol and nylon

Claims (10)

1. CLAIMS P. Apparatus for milling at least two surfaces of a workpiece, the apparatus comprising a base having a longitudinal axis along which the workpiece moves, in use, said base carrying adjustable clamping means whereby a workpiece can be vertically and laterally, but not axially, clamped in position relative to the base, a milling head frame movable vertically and laterally relative to the base, one or more motors for effecting each degree of movement of the milling head frame relative to the base, and at least two milling heads rotatably mounted on the milling head frame each for carrying a milling cutter so as to be positioned facing towards the surfaces of the workpiece to be milled, and one or more milling head motors for driving the milling heads.
2. 2. Apparatus according to Claim 1, wherein the clamping means comprise pairs of rollers between which the workpiece is clamped, in use.
3. 3. Apparatus according to Claim 2 wherein each roller of each pair of rollers is substantially parallel to the other of the pair.
4. 4. Apparatus according to Claim 2 or Claim 3, wherein at least one pair of rollers is provided extending substantially vertically and at least one pair of rollers is provided extending substantially horizontally and laterally relative to the base.
5. 5. Apparatus according to any of the preceding Claims wherein the milling head frame is located between two axially successive sets of rollers.
6. 6. A frame according to Claim 5, wherein the gap between the two successive roller sets is large enough to accommodate the milling head itself but as short as possible to give maximum rigidity of clamping by the rollers.
7. 7. Apparatus according to any preceding Claim, wherein an actuator is provided mounted to the base to cushion the vertical movement of the milling head frame.
8. 8. Apparatus according to any preceding Claim wherein a linear actuator beam is provided to advance the workpiece toward the milling head.
9. 9. Apparatus according to any preceding Claim, wherein a table is provided leading up to the milling head to support the workpiece as it is advanced towards the milling head.
10. 10. Apparatus according to any preceding Claim, wherein a circular saw is mounted close to the last roller of the successive roller sets to cut off finished milled sections of the workpiece.