EP0102806A1

EP0102806A1 - End-forming of timber strips and an end-forming woodworking machine

Info

Publication number: EP0102806A1
Application number: EP83304878A
Authority: EP
Inventors: William Boardman
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-08-24
Filing date: 1983-08-24
Publication date: 1984-03-14
Also published as: GB2125729A; GB8322689D0

Abstract

@ The invention is concerned with a machine for forming the ends of timber strips, in particular for forming tenons on the ends of components for making up into frames. A cutter (72) is moved in a lateral direction with one end of the workpiece (16) engaging with the cutter, the workpiece and cutter are then moved relatively to each other in a longitudinal direction and again there is relative lateral movement between the cutter and the workpiece in the direction opposite to the first lateral direction, with the opposite end of the workpiece engaging with the cutter so that the same formation is formed at the opposite end of the workpiece. In the preferred method, the cutter forms the trailing end of a first workpiece and the leading end of a second following workpiece at each lateral motion. The invention also includes a machine for carrying out these forming operations automatically.

Description

The invention is concerned with the end-forming of timber strips: generally for the purpose of forming joints with other components. It is to be understood however that the expression "timber" as used in this specification, is intended to include in addition to ordinary timber, reconstituted timber and timber substitutes such as plastics materials. The most common end-formation on a timber strip is a tenon or a mortise slot, and the invention provides a method and apparatus for forming tenons or mortises on the ends of timber strips - such as the strips used in door or window frame construction for example. It is to be understood that the invention is not restricted to the formation of tenons and mortises, since it could be used to produce any other formation which can be machined on the end of a strip.
In a conventional tenoning machine, the workpiece is moved in a lateral direction parallel to the end on which the tenon is to be formed, past and in engagement with a rotary cutter. The cutter removes a slice or slices of material from the end of the workpiece, leaving a tenon on the workpiece. Alternatively, if a mortise is being formed, a slice is removed from a median position forming a slot between two projecting tongues. It will be appreciated that the shape and size of the tenon or slot is determined by the dimensions of the cutter and the length the workpiece is fed into the cutter at the commencement of the traversing motion. Further, the cutter may be of composite form, so that it is adapted to produce two or more tenons at the same time on the end of the workpiece.
There are many instances in woodworking, in which it is required to form a tenon or other formation at opposite ends of a workpiece. With the conventional tenoning machine, it is necessary after forming one end, to remove the workpiece from the machine, turn it round, and then perform the forming operation at the other end.
According to a first aspect of this invention a timber workpiece is end formed at opposite ends by the steps of: relative movement between a cutter and the workpiece in a lateral direction with one end of the workpiece engaging with the cutter to produce the formation at that end of the workpiece; relative movement between the cutter and the workpiece in a longitudinal direction, and relative lateral movement between the cutter and the workpiece in the direction opposite to the first lateral direction, with the opposite end of the workpiece engaging with the cutter to produce the formation at the said opposite end of the workpiece.
Preferably, the cutter is moved to produce the lateral relative motion, and the workpiece is moved to produce the longitudinal relative motion. With this preferred method, the cutter has only rectilinear motion, and the workpiece has only rectilinear motion. Consequently, the mechanisms which have to be provided on the machine for carrying out the necessary movement of the cutter and the workpiece, can be relatively simple, since there is no question of right angle motion of either the cutter or the workpiece.
In the preferred method, during the second relative lateral movement between the cutter and the workpiece, a second workpiece is in engagement with the side of the cutter on which the first end formation was formed, so that end formations are being formed simultaneously, on opposite ends of two workpieces. If the relative lateral motion is produced entirely by movement of the cutter, as is preferred, then the cutter has a reciprocatory rectilinear motion, and in one direction is used to produce a second end formation on the trailing end of a first workpiece, and a first end formation on the leading end of the second workpiece, whilst in the return motion, the cutter produces a second end formation on the trailing end of the said second workpiece, and a first end formation on the leading end of a third workpiece. Thus, after the first workpiece has been moved longitudinally to the position at which the second end formation can be formed on it, two end formations are being formed simultaneously at each lateral motion of the cutter. It will be appreciated therefore, that a high rate of productivity can be obtained by use of this method.
According to a second aspect of the invention an end-forming woodworking machine comprises: first and second locating and clamping mechanisms each adapted to hold a timber strip, and longitudinally aligned with each other but longitudinally spaced apart, so that a timber strip can travel in a simple longitudinal direction from the first to the second locating and clamping mechanisms, and a carriage positioned adjacent to the space between the two locating and clamping mechanisms, the carriage being provided with a rotatable spindle for mounting a cutter, the spindle extending in one lateral direction, and the carriage being adapted for reciprocation in a lateral direction at right angles to the spindle axis, so that during a pass of the carriage in either direction, a cutter on its spindle can engage with the trailing end of a timber strip in the second locating and clamping mechanism and with the leading end of a timber strip in the first locating and clamping mechanism. In a convenient arrangement, the spindle axis is vertical and the carrier is adapted to move horizontally.
Preferably the carriage also supports the driving motor for the spindle and a cutter on the spindle, the carriage being adapted for sliding reciprocatory motion on a stationary framework of the machine.
Preferably power driven feeding means are provided for moving a workpiece from the first locating and clamping mechanism to the second locating and clamping mechanism. It is further preferred that automatic control means are provided for operating the locating and clamping mechanisms and the carriage movement to perform a sequence comprising: clamping the workpiece in the first locating and clamping mechanism; traversing the carriage in one laterial direction; releasing the first clamping mechanism; feeding the workpiece to the second locating and clamping mechanism; clamping the workpiece in the second clamping mechanism and traversing the carriage in the opposite lateral direction.
According to another preferred feature of the invention, each locating and clamping mechanism comprises two side-by-side clamps adapted for simultaneous operation, so that two workpieces can travel together through the machine. In a still further preferred arrangement, there is provision for mounting a plurality of cutters on the spindle in a stack and for moving the spindle relatively to the locating and clamping mechanisms to bring a selected one of the cutters on the spindle into operative alginment with a workpiece in either of the locating and clamping mechanisms.
An end-forming woodworking machine in accordance with the second aspect of the invention, and its method of use in accordance with the first aspect of the invention, will now be described by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a diagrammatic elevation of the machine,
Figure 2 is a perspective detail view of a clamping mechanism on the machine,
Figure 3 is a diagrammatic plan view illustrating certain relative motions between a workpiece and a cutter, and
Figure 4 is a perspective view showing a cutter and two workpieces in the machine.

The machine which is illustrated in the drawings, is mainly intended to be used for tenoning the ends of timber strips, for use in assembled frames such as window frames or door frames. It will be appreciated, that it could be used for many other kinds of end formation on timber strips, but for the purpose of the present exemplary description, reference will be made only to the production of tenons. Further; the machine is adapted for semi-automatic operation, and for this purpose, it is equipped with various sensors, such as limit switches or fluidic detectors, by means of which it is possible to control various operative parts of the machine in a required sequence for the semi-automatic operation. Since this kind of control arrangement is well known, it is not described in detail.
A stationary framework for the machine essentially comprises a front frame 10, and a rear frame 12, the two frames being in longitudinal alignment with each other, but spaced apart longitudinally, so that there is a gap indicated generally at 14 between the two frames. Each of the frames 10 and 12 provides a table on which a workpiece such as a timber strip illustrated in chain-dotted lines at 16 can be placed. In practice, as will hereinafter appear, the table is wide enough to accommodate two strips 16 side-by-side, and the machine is adapted to operate on two sets of workpieces in this side-by-side arrangement.
An adjustable end location device 18 is provided on the front frame 10, and this incorporates a detector 20 against which the trailing end of a workpiece 16 can be pressed when the workpiece is placed on the front table. The sensor 20 is adapted to initiate the operation of the machine when it is actuated by the presence of a workpiece on the front table.
For locating the two strips 16 laterally of the front frame, there is a central stationary block 22 (see also Figure 2) upstanding from the front table, and extending longitudinally in the region of the rear end of the front table. At each side of the block 22, there is a fixed upstanding mounting plate 24, and a movable clamping plate 26 has two guide rods 28 and 30 which extend through holes in the adjacent mounting plate 24, so that the clamp plate 26 is movable horizontally, in a direction lateral of the machine, and towards and away from the central block 22. A hydraulic ram-and-cylinder device 32 is fastened to the mounting plate 24, and the ram is attached to the clamp plate 26. The ram-and-cylinder device 32 is employed for the purpose of moving the clamp plate 26 towards and away from the central block 22. When a workpiece 16 is placed on the front table, its forward end passes through'the space between one side of the block 22 and one of the clamp plates 26, and when the ram-and-cylinder device 32 is then operated, the workpiece is clamped and located laterally of the machine between the block 22 and the clamp plate 26.
A bridge 34 extends across the rear end of the front frame 10, and carries a pair of pneumatic or hydraulic ram-and-cylinder devices 36, each of which is provided with a clamping disc 38 at its lower end, these discs 38 being aligned with and capable of entering the space between respective sides of the central block 22 and the clamp plates 26. Hence, when the ram-and-cylinder devices 36 are operated, they project their discs 38 into engagement with the top surfaces of the workpieces 16 held in the lateral clamps, for the purpose of holding the workpieces against vertical movement. It will be noted, that the clamping arrangement is particularly effective at the rear end of the frame 10, but the arrangement is such, that when the workpiece is positioned on the frame 10, the rear end of the workpiece extends part way across the gap 14 between the two frames 10 and 12.
The rear frame 12 is provided with a clamping arrangement indicated generally at 40, which is identical with the clamping arrangement on the front frame, but with the central block and the clamp plates extending rearwardly from the gap 14. It will be appreciated, that it is possible to slide the workpieces 16 from the table on the front frame 10, across the gap 14 and on to the table on the rear frame 12. This requires only a simple longitudinal sliding motion, and in this particular arrangement, this is provided for by a drive wheel 42 carried by a ram 44 extending vertically downwards from a pneumatic cylinder 46, which in turn is carried by a bridge piece 48 forming part of the stationary framework of the machine. When an appropriate signal is received from the automatic control apparatus, the wheel 42 is pressed down on to the workpiece 16, and is then rotated, by a power driven means (not shown) so that its frictional engagement with the workpiece causes the workpiece to slide horizontally from the front table to the rear table. To assist in this, a transfer plate 50 is hinged to the rear end of the front table, and is adapted to be raised by a ram-and-cylinder device 52, into a position, where it extends across the gap from the front table to the rear table. In practice, the transfer plate 50 may be arranged so that its rear edge is slightly above the level of the rear table, in the raised position of the transfer plate, so that when the ram-and-cylinder devices controlling the vertical clamps at 40 are operated, the workpiece is pressed downwardly, on to the rear table, at the same time deflecting the transfer plate 50 downwardly to bring its rear edge level with the top of the rear table.
A feed arrangement 54 is also provided and is identical with the arrangement 42, 44, 46 and 48 above the front table, the wheel 56 of the rear feed mechanism being adapted to cause a workpiece to slide rearwardly along the rear table, away from the clamping arrangement 40. It will understood, that each of the feed mechanisms is equipped with two wheels 42 and 56, one for engagement with each of the two side-by-side workpieces 16 on the machine.
The machine is provided with a carriage, indicated generally at 60 in Figure 1, and this carriage is located in the gap 14, and adapted for transverse motion on a cross slide 62 secured to the front end of the rear frame 12. There are various mechanisms which can be used for producing the transverse motion of the carriage 60. For example, the ends of a chain stretched around sprocket wheels disposed one at each side of the machine could be attached to the carriage 60, so that when one of the sprocket wheels is rotated, the carriage is pulled to one side of the machine. Alternatively, the carriage motion could be derived from a hydraulic or pneumatic ram-and-cylinder arrangement or from a rack-and-pinion arrangement. Limit switches or fluidic detectors, are provided, to control the driving mechanism, and to arrest the carriage at each end of its permitted lateral motion.
A circular saw 64 is mounted on a spindle extending from a housing 66, and a driving motor (not shown) for the circular saw is mounted on the carriage 60. Provision is made for raising and lowering the housing 66, so that the circular saw 64 can be set in a required vertical position. It will be appreciated, that as the carriage 60 is moved laterally, and the circular saw 64 rotated, the saw will cut through any part of the timber workpieces 16 projecting into the path of the circular saw, as indicated by the chain-dotted line position of the workpiece 16 shown in Figure 1.
Also, the carriage 60 provides a mounting for an electric motor 68, the output shaft of which is formed into a spindle 70, projecting vertically. The spindle 70 provides a mounting for cutters 72 (Figures 3 and 4) used in the formation of tenons on the ends of the workpieces 16. Such a cutter has two cutting discs, with a smaller diameter spacer between them, so that it is adapted to remove two slices of material from the end of the workpiece, leaving the central tenon projecting from the body of the workpiece. Tenoning cutters are in themselves well known, and there is no need for further detailed description. It will be appreciated, that if it is required to form a mortise slot instead of a tenon, then a single disc type cutter is employed. It will also be appreciated, that more elaborate formations could be produced on the end of the workpiece, by an appropriately shaped cutter. The electric motor 68, and its spindle 70, are also adjustable vertically on the carriage 60, to provide for correct positioning of the cutter or cutters on the spindle 70 relatively to workpieces on the tables of the machine.
The operation of the machine will now be described. In the first place, two timber blanks, required to produce identical components, are positioned on the front frame 10, as previously described, leaving the forward ends of the blanks projecting beyond the rear end of the frame 10. The longitudinal distance between the trailing end location stop provided by the detector 20, and the front side face of the circular saw 64, is equal to the length of the required finished component. When the detector 20 senses that the workpieces are in position, the clamps 24, 26, 36 and 38 are all operated, so that the two workpieces are firmly clamped to the front table. At this stage, the carriage 60 is displaced to one side of the machine frames 10 and 12. Both the circular saw 64 and the tenoning cutter are rotated about their respective axes, and the carriage 60 is then moved from that side of the machine where it was located, to the opposite side, in other words, it has a transverse motion relatively to the workpieces 16. During this motion, assuming that the circular saw 64 is in advance of the tenoning cutter, the saw first cuts off the ends of the blanks, thus reducing the blanks to the-correct length for the finished components, and this is followed by the tenoning cutter removing strips of material from the ends of the blanks, to form tenons on the two workpieces.
When the carriage 60 arrives at the end of its lateral motion, a signal from the limit switch or fluidic detector causes the clamps 24, 26 and 38 to be released, and at the same time, the drive wheels 42 are lowered into engagement with their respective workpieces 16, and the transfer plate 50 is raised by operation of the ram-and-cylinder 52. The drive wheels 42 cause the workpieces 16 to slide across the transfer plate 50, on to the table on the rear frame 12. Because this is a simple rectilinear motion, it is easy to provide and control. Shoulder stops (not shown) are provided on the rear frame 12, and these are.engaged by the roots of the tenons formed on the workpieces, when the latter have arrived at a required longitudinal location on the rear frame 12. Operation of the shoulder stops causes the clamping arrangement 40 on the rear table to be actuated, and this clamps the two workpieces to that table. The carriage 60 is then traversed in the opposite laterial direction to its original direction of motion, and the tenoning cutter on the spindle 60 then removes slices of material from the trailing ends of the workpieces 16, forming tenons on those trailing ends. When the carriage 60 arrives at the end of its transverse motion (i.e. back in the starting position) a limit switch or fluidic detector senses its arrival, and signals release of the clamping arrangement 40, and operation of the drive wheels 56, to slide the workpieces 16 away from the tenoning position. It will be appreciated, that in this manner tenons have been formed on both ends of each of the two workpieces.
When the first two workpieces are transferred to the rear table, two fresh blanks are placed on the front frame 10, to replace the first pair of blanks. This second pair of blanks causes actuation of the clamps 24, 26 and 38 as previously described, and this is simultaneous with the operation of the clamping mechanism 40 operating at that time on the first pair of workpieces. Hence, there are then two workpieces 16 clamped on the rear frame 12, and two following workpieces 16 clamped on the front frame 10. When the carriage 60 moves back to its original position, the tenoning cutter on the spindle 70 will form the tenons on the trailing ends of the first pair of workpieces as previously described, and will at the same time form tenons on the leading ends of the following pair of workpieces on the front frame 10, and the circular saw 64 will cut the following pair of workpieces to the required component length. Thus, during every pass of the carriage 60 after the first, tenons are being formed on the trailing ends of one pair of workpieces, and simultaneously, tenons are being formed on the leading ends of a following pair of workpieces.
This method is illustrated diagrammatically in Figures 3 and 4, which show the basic conception on which the invention is based. A workpiece 16 is shown at the lefthand side of Figure 3 in the position it occupies when clamped on the front frame 10. (For the purpose of Figures 3 and 4, only a single workpiece is illustrated on each of the tables, although as explained previously, in practice two workpieces are clamped side-by-side on each table.) This workpiece 16 is moved in a simple rectilinear fashion by the drive wheel 42, in the direction of the arrow A to transfer it from the front table to the rear table. The position of the workpiece when it is clamped on the rear table is indicated in Figure 3 at 16a. Figures 3 and 4 also illustrate the starting position of the tenoning cutter 72 in full lines, and the position of the after a single lateral motion in the direction of the arrows B is shown at 72a. The direction of rotation of the cutter is shown at C. Assuming that there are workpieces at both the positions 16 and 16a, then during the traverse of the cutter 72 from the position shown in full lines to the position shown in chain-dotted lines at 72a, it will cut a strip 74 from the leading end of the workpiece 16, and a strip 74a from the trailing end of the workpiece 16a, to leave tenons on these ends of the two workpieces. The carriage 60 only has a simple rectilinear motion to produce this effect, and this enables a simple drive mechanism to be employed.
After the first pass of the cutter 72, the workpieces are moved forwardly in the direction of the arrow A, so that the workpiece 16 takes up the position 16a for the formation of a tenon on its trailing end, and a fresh workpiece is brought into the position 16. The cutter 72 then returns transversely to its starting position, and in doing so, again removes slices of material from the ends of the two workpieces, to form tenons.
In a refinement of the machine just described, the spindle 70 is formed with two locations for different cutters, and by raising and lowering the motor 68 with its spindle 70, either of these cutters can be brought.into operative alignment with the workpieces, to form different profiles on the ends of the workpieces during transverse motion of the carriage 60.

Claims

1. A method of end-forming a timber workpiece at opposite ends, comprising the steps of:relative movement between a cutter and the workpiece in a lateral direction with one end of the workpiece engaging with the cutter to produce the formation at that end of the workpiece; relative movement between the cutter and the workpiece in a longitudinal direction, and relative lateral movement between the cutter and the workpiece in the direction opposite to the first lateral direction, with the opposite end of the workpiece engaging with the cutter to produce the formation at the said opposite end of the workpiece.

2. A method of end-forming a timber workpiece as claimed in Claim 1, in which the cutter is moved to produce the lateral relative motion, and the workpiece is moved to produce the longitudinal relative motion.

3. A method of end-forming a timber workpiece as claimed in either of Claims 1 and 2, in which during the second relative lateral movement betwen the cutter and the workpiece, a second workpiece is in engagement with the side of the cutter on which the first end formation was formed, so that end formations are being formed simultaneously, on opposite ends of the two workpieces.

4. An end-forming woodworking machine comprising: first and second locating and clamping mechanisms each adapted to hold a timber strip, and longitudinally aligned with each other but longitudinally spaced apart, so that a timber strip can travel in a simple longitudinal direction from the first to the second locating and clamping mechanisms and a carriage positioned adjacent to the space between the two locating and clamping mechanisms, the carriage being provided with a rotatable spindle for mounting a cutter, the spindle extending in one lateral direction and the carriage being adapted for reciprocation in a lateral direction at right angles to the spindle axis, so that during a pass of the carriage in either direction, a cutter on its spindle can engage with the trailing end of a timber strip in the second locating and clamping mechanism and with the leading end of a timber strip in the first locating and clamping mechanism.

5. An end-forming woodworking machine as claimed in Claim 4, in which the spindle axis is vertical and the carriage is adapted to move horizontally.

6. An end-forming woodworking machine as claimed in either of Claims 4 and 5, in which the carriage also supports the driving motor for the spindle and a cutter on the spindle, the carriage being adapted for sliding reciprocatory motion on a stationary framework of the machine.

7. An end-forming woodworking machine as claimed in any one of Claims 4 to 6, in which power driven feeding means are provided for moving a workpiece from the first locating and clamping mechanism to the second locating and clamping mechanism.

8. An end-forming woodworking machine as claimed in Claim 7, in which automatic control means are provided for operating the locating and clamping mechanisms and the carriage movement to perform a sequence comprising: clamping the workpiece in the first locating and clamping mechanism; traversing the carriage in one lateral direction; releasing the first clamping mechanism; feeding the workpiece to the second locating and clamping mechanism; clamping the workpiece in the second clamping mechanism and traversing the carriage in the opposite lateral direction.

9. An end-forming woodworking machine as claimed in any one of Claims 4 to 8, in which each locating and clamping mechanism.comprises two side-by-side clamps adapted for simultaneous operation, so that two workpieces can travel together through the machine.

10. An end-forming woodworking machine as claimed in any one of Claims 4 to 9, in which there is provision for mounting a plurality of cutters on the spindle in a stack and for moving the spindle relatively to the locating and clamping mechanisms to bring a selected one of the cutters on the spindle into operative alignment with a workpiece in either of the locating and clamping mechanisms.

11. An end-forming woodworking machine as claimed in any one of Claims 4 to 10, in which a circular saw is mounted on the carriage for cutting the workpieces to length.