GB2177634A

GB2177634A - Multiple-spindle milling machine

Info

Publication number: GB2177634A
Application number: GB08514670A
Authority: GB
Inventors: Thomas Green
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-06-11
Filing date: 1985-06-11
Publication date: 1987-01-28
Also published as: GB8514670D0; GB2177634B

Abstract

For milling at least two surfaces of a work piece e.g. a box-section channel 2, a spindle head 3 has rotably mounted upon it at least two spindles 4, each spindle rotating a cutter 5, the cutters being arranged such that in use they face towards the surfaces of the work piece, and a spindle drive motor 6 for rotating the spindles simultaneously, the spindle head being mounted for movement to allow the required shapes to be milled from the surfaces of the work piece. The spindle head 3 is movable in three mutually perpendicular directions on ways by ball-screws and microprocessor controlled stepping motors 10, 15, 20. The work-piece is clamped either side of the spindle head by pneumatic clamps 23, 24. Each cutter 5 is clamped in its holder by an offset screw with a tapered end engaging a cutter shank groove. <IMAGE>

Description

SPECIFICATION Milling Machine Field of the invention The invention relates to a milling machine, and in particular to a milling machine for milling a work piece which has at least two surfaces to be milled. Such a milling machine works with particular advantage with the elongate box section channels for the double glazing industry for forming window and door frames.

In many situations slots and groves have to be milled out of different surfaces of a particular work piece. At present milling machines are 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 the machine for the next surface to be milled. Several machines have been designed to try to overcome this problem. These include at least two independantly moved cutters. Since the movement of each cutter has to be independantly controlled the resulting machines are very bulky and therefore expensive.

Summary of the invention According to the invention there is provided apparatus for milling at least two surfaces of a work piece, the apparatus comprising a spindle head having rotably mounted upon it at least two spindles, each spindle rotating a cutter, the cutters being arranged such that in use they face towards the surfaces of the work piece to be milled, and a spindle drive motor for rotating the spindles simultaneously, the spindle head being mounted for movement to allow the required shapes to be milled from the surfaces of the work piece.

This apparatus is produced which can cut the required slots from each surface of the work piece without having to move the work piece within the machine. By movement of the spindle head first one surface may be milled by moving the associated cutter towards one surface and then the second surface can be milled by moving the second associated cutter towards the surface.

Preferably the spindle head is slidably mounted with respect to a first shaft, the first shaft being slidably mounted with respect to a second shaft at right angles to the first shaft, and the second shaft is slidably mounted with respect to a third shaft lying at right angles to the first and second shafts.

In this way the spindle head can move independantly in three directions at right angles to each other. This gives very great flexibility in movement of the spindle head.

Preferably the slidable movement between the shafts is achieved by linear bearings running on slide ways. This serves to minimize friction during traversing to allow for rapid positioning of the spindle head.

Preferably the movement of the cutter head on the first shaft, and of the first shaft with the respect of the second shaft, and in the second shaft with respect to the third shaft is achieved by using ball srews and nuts driven by independantly controlled stepper motors.

Preferably the stepper motors are controlled by a micro processor so that a pre-determined number of operations can be programmed into the micro processor to achieve the correct shapes to be milled out of each surface of the work piece.

The invention may advantageously be used to mill the box section channels for door and window frames. In this case there are three outwardly facing surfaces which require milling. It is preferred therefore that the apparatus includes three cutters mounted on the spindle head all facing inwardly towards the surface to be milled.

The most preferred arrangement is for a first cutter to face downwards towards the base of the channel and for two cutters to be arranged parallel to each other and parpendicular to the first cutter or facing towards each other to cut the sides of the channel.

In this case it is preferred that the cutting head is slidably mounted on a first shaft parallel to the second and third cutters. The first shaft is preferably mounted slidably with respect to a second shaft lying parallel to the first cutter and the second shaft is slidably mounted on a third shaft lying parallel to the axis of the elongate work piece.

The cutter used are preferably standard ones used in milling machines. These are known as router cutters and are required to be rotated in a clockwise direction. A spindle head is arranged to transmit rotation to the spindles all the same direction.

Preferably the transmission of drive to the spindles is by a drive belt. This is because the drive belt may be twisted about 90 degrees and still efficiently transmit rotation.

Hitherto router cutters have been fastened into their spindle by inserting a cutter into a bore in the spindle and then locking it into position by inserting a locking screw radially towards the cutter until it contacts the cutter to lock it into place. In this case it is preferred that the locking screw is not inserted radially towards but is off set slightly such that the wedge shaped end of the locking screw may exert a wedge action when tightened towards the cutter shaft. This gives a much more efficient method of locking the cutter into position on the spindle.

Brief description of the drawings Apparatus 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 schematic perspective view of the apparatus; Figure 2 is a schematic section through the apparatus; Figure 3 is a section through part of the spindle head; and Figure 4 is a section taken along X-X of Figure 3.

Description of the preferred embodiment Apparatus 1 is for milling three surfaces of a work piece 2 in the form of boxed section channels used in the double glazing industry for door and window frames. In machine 1 may equally be used for milling aluminimum or pvc window frames.

The apparatus 1 comprises a spindle head 3 having rotatably mounted upon it three spindles 4 cutters 5 are arranged such that in use they face towards the surfaces of the work piece 2 to be milled.

The apparatus also includes a motor 6 for rotating the spindles 4. The spindle head 3 is mounted to allow movement so that the required shapes may be milled from each surface of the work piece 2.

The spindle head 3 forms part of the housing 6 having mounted within it 2 linear bearings 7 and 8 which run on slid way 9. The axis of slide way 9 is denoted Y in Figure 2. A stepper motor 10 is coupled to a ball nut and lead screw (not shown) which serves to move the spindle head 3 in direction Y.

The slide way 9 is mounted upon a housing 11 which has mounted within it two linear bearings 12 and 13 which run along slide way 14. The slide way 14 is in a vertical position and perpendicular to the first slide way 9. The axis of slide way 14 is denoted Z in figure 2. A stepper motor 15 is coupled to a ball nut and lead screw (not shown) to serve to move the housing 11 in direction Z along slide way 14.

Slide way 14 is mounted upon a housing 16 including two linear bearings 17 and 18 which run along linear slide way 19 which is perpendicular to slide way 14 and slide way 9. The axis of main slide way 19 is denoted X in Figure 2. A stepper motor 20 is coupled to a ball nut and lead screw (not shown) which drives the housing 16 along slide way 19 in direction X. The shaft 19 is rigidly attached to box section 21 which forms part of the base of the bed of the apparatus (not shown). Also mounted to box section 21 are a pair of pneumatic clamps 22 which are used to clamp the work piece 2 in position. Pneumatic clamp 22 is operated by pneumatic cylinder 23 which controls the movement of pusher 24 so that the work piece 2 may be held firmly in position.

The pneumatic clamps 22 are spaced apart and lie at either side of the spindle head 3 so that the pneumatic clamps may hold the work piece 2 at its ends between which the slots required are to be milled.

The work piece 2 is inserted into the machine so that it lies parallel to the slide way 19 in direction X. The length of trasverse allowed in the machine is 600 millimetres in the X direction, 150 millimetres in the Y direction and 150 millimetres in the Z direction.

Spindle motor 6 is a one and a half horse power 440 volt motor which drives shaft 25 and therefore drive belt 26. The drive belt in this case is a "multi V' drive belt which in this case is sold as "Poly-V (J Section)' by J H Fenner & Co of England. The first belt 26 is coupled to first spindle 27 which rotates about a vertical axis to rotate cutter 28 for milling the first base surface 29 of work piece 2. Similar drive belts 30 and 31 extend from spindle 27, are rotated through 90 degrees and are then wound around idler pulleys 32 and 33 respectively. They are then rotated through 90 degrees again before driving spindle 34 and 35 respectively. Spindles 34 and 35 both rotate in a horizontal axis and rotate cutters 36 and 37 respectively which face in towards each other and are for milling the sides 38 and 39 of work piece 2.The spindles are rotated in the same direction at a speed of 1200 rpm.

Throughout the milling operation the cutters 28, 36 and 37 rotate simultaneously and the spindle head 3 is moved successively in directions X, Y and Z to achieve the correct shapes to be milled out of surfaces 38, 29 and 39 respectively.

The stepper motors 10, 15 and 20 all run at a speed of 200 steps per revolution. They can be obtained, together with suitable linear bearings, slideways, ball nuts, lead screws and controls for the stepper motors from Unimatic Engineers of 122 Granville Road, Cricklewood, London, England. The stepper motors 10 and 15 and 20 are all controlled by a micro processor (not shown) which in this case is a Euro CUBE and is sold by Control Universal Limited of 139 Ditton Walk, Cambridge, Engand.

The method of mounting a cutter within a spindle is shown in Figure 3. Only one cutter 36 is shown but the other two cutters are mounted identically. The cutter 38 is inserted into a bore 40 in the spindle. A locking screw 41 is inserted towards the cutter 36 in a direction parallel but off set from radial so that the wedge shaped head of 42 of the locking screw 41 exerts a wedging effect on the cutter 38 to tighten it and lock it into position.

It will be appreciated that the machine may be used to mill channels of many different shapes and may be modified to allow traverse of the spindle head 3 of a greater distance, especially in the X-direction to allow handling of channels of great lengths.

Claims

Apparatus for milling at least two surfaces of a work piece, the apparatus comprising a spindle head having rotably mounted upon it at least two spindles, each spindle rotating a cutter, the cutters being arranged such that in use they face towards the surfaces of the work piece to be milled, and a spindle drive motor for rotating the spindles simultaneously, the spindle head being mounted for movement to allow the required shapes to be milled from the surfaces of the work piece.
2. Apparatus according to Claim 1 and in which the spindle head is slidably mounted with respect to a first shaft, the first shaft being slidably mounted with respect to a second shaft at right angles to the first shaft, and the second shaft is slidably mounted with respect to a third shaft lying at right angles to the first and second shafts.
3. Apparatus according to Claim 2 and in which the slidable movement between the shafts is achieved by linear bearings running on slideways.
4. Apparatus according to Claim 2 or Claim 3 and in which the movement of the cutter head on the first shaft, and of the first shaft with respect to the second shaft, and in the second shaft with respect to the third shaft is achieved by using ball screws and nuts driven by independently controlled stepper motors.
5. Apparatus according to Claim 4 and in which the stepper motors are controlled by a microprocessor.
6. Apparatus according to any of the preceding Claims and including three cutters mounted on the spindle head all facing inwardly towards the surfaces to be milled.
7. Apparatus according to Claim 6 and for cutting box section channels and in which a first cutter faces downwards towards the base of the channel and in which the other two cutters are arranged parallel to each other and perpendicular to the first cutter or facing towards each other to cut the sides of the channel.
8. Apparatus according to Claim 7 and in which the cutting head is slidably mounted on a first shaft parallel to the second and third cutters.
9. Apparatus according to Claim 8 and in which the first shaft is mounted slidably with respect to a second shaft lying parallel to the first cutter and the second shaft is slidably mounted on a third shaft lying parallel to the axis of the elongate work piece.
10. Apparatus according to any of the preceding Claims and in which the transmission of drive to the spindles is by a drive belt.
11. Apparatus according to any of the preceding Claims and in which at least one of the cutters is held in place on its associated shaft by a locking screw which, instead of being inserted radially, is offset such that the end of the locking screw exerts a wedge action on the shaft as the screw is tightened into its cutter-holding position.
12. Apparatus substantially as described herein with reference to and as illustrated in the accompanying drawings.