GB2199607A - Trimming venetian blinds - Google Patents

Description

4t "APPARATUS TO TRIM AN:ASSEMBLED VENETIAN BLIND TO A GIVEN LENGTH" 1; 2

199607 This invention provides a machine for trimming the ends of assembled venetian type blinds. Venetian blinds are comprised of a head rail, a bottom rail and slats supported by cross members of.ladder tapes fixed at their ends to the head and bottom rails. Cords fixed to the bottom rail and passing through slots in the slats are passed over pulleys in the head rail. By pulling on the cords the slats are gathered together as the bottom rail is lifted to the head rail.

At this time venetian 'blinds are made up in quantity for supply.to persons with standard width windows. If a person requires a venetian blind for a non-standarOwidth wiridow it has to be made as a special order with the head and bottom rails and slats being made to the correct lengths and then assembled with ladder tapes and cords. This prevents the sale of non-standard width venetian blinds in retail stores. In commerce venetian blinds are said to have a width (the side to side distance) and a drop (the top to bottom distance). For convenience in this specification hereinafter the side to side distance of a venetian blind will be termed its length.

This invention has been made so that a retail store which holds a range of assembled venetian blinds of-.,_ different lengths can trim unwanted length from a blind to 1 1 provide a customer's length requirement. A possible range would provide a 150mm. difference between blind lengths with the cord pulleys and ladder tapes located no closer than 150 mms from each end of the blind. If the maximum 150mms was cut from a blind, say 75mms from each end of the blind, then there would still be an acceptable distance of 75mms between the ends of the blind and the ladder tapes.

Broadly the invention can be said to comprise a length trimming machine for the slats of an assembled and extended venetian blind comprising a head rail and a bottom rail connected by ladder tapes with slats supported in the ladder tapes, the machine comprising a head rail support, head rail clamping means on the head rail support, a bearing means at each end of the head rail support, two vertical posts respectively engaged in the bearing means, first drive means to raise and lower the head rail support on the posts, slat trimming means comprising two trimming units, each trimming unit including a blade carriage engaged with a carriage raising and lowering means, a blade assembly comprised of a pair of relatively movable slat trimming blades, the blade assembly is mounted on the blade carriage so as to be movable horizontally on the blade carriage between a rest position and work position where the-blades are in cutting relationship with the slats of a blind mounted in the machine, means to move the blade pair between the rest and work positions and means to move the blades one relative to the other, a carriage support for each blade I 1 3 - carriage, each carriage support including a vertical track and a means to move its associated blade carriage along the vertical track, upper and lower horizontal guides each including a horizontal track. the upper and lower ends of the carriage supports are respectively engaged in the tracks of. the upper and lower horizontal guides for movement therealong by carriage support moving means, and control means to selectively operate the first drive means, the means to move the blade pairs between the rest and work positions, the means to move the blades one relative to the other, the means to move the blade carriages in the vertical tracks and the carriage support means in the tracks in the horizontal guides.

A presently preferred embodiment of the invention will now be described With reference to the accompanying drawings in which: Fig.1 is a perspective view of the machine of the invention, Fig.2 is a fragmentary view of the engagement between a blade carriage support and its supporting and guiding means, Fig.3 is a cut away perspective view a blade carriage and blade assembly in the rest condition, Fig.4 is a view similar to Fig.3 showing the blade assembly in a work position, Fig.5 is a view similar to Fig.4 showing the blade assembly engaged in a cutting operation, FigA is a schematic view showing a first condition of operation for the slat detector, 4 - Fig.7 is a view similar to Fig.6 showing the slat detector in the detection condition, and Fig.8 is a view similar to Fig.6 showing the slat detector in a bottom rail detecting condition.

In Fig.1 the machine will be seen to comprise a frame 1 including a back 2, sides 3 and 4 (portions of which have been cut away to facilitate the description of the machine), a base housing 5 and a work table 6. Fixed to the back 2 there are upper and lower horizontal guides 7 and 8 10 respectively each including a track 9 and 10.

Two vertical carriage support members 11 and 12 are mounted at their ends on the guides 7 and 8. At the upper ends of the support members 11 and 12 there are drive units 14 each having an associated drive wheel 13 which drivingly engages in the track 9, which is of T form. The lower ends of the members 11 and 12 there are non-driven support wheels (not shown) engaged in the T shaped track 10. The supports 11 and 12 are of channel form with the channel legs turned inwardly as indicated 15 to form tracks 16. Inside each support member 11 and 12 there is a threaded feed screw 17 supported in bearing means at the lower ends of the support members 11 and 12 (not shown) and at the upper end the screws 17 are coupled to bidirectional electric motors 19 fixed to the end plates 18 of the members 11 and 12.

There is a threaded nut 20 on each screw 17 and an arm 21 projecting horizontally from the nut 20 passes 4 c 1 through the track 16 of the associated support 11 or 12 and is guided by the track as the nut 20 is moved up and down the screw 17 as it is rotated by the motor 19. A blade carriage 22 is fixed to each arm 21 and a blade assembly is mounted on each blade carriage. The blade assembly in its three operational conditions is illustrated in Figs.3 to 5. From Fig.3 it will be seen that the blade carrier 22 includes a guideway 23 and a support surface 24. A blade holder 25 has an upstanding lug 26 engaged in the guideway 23 and it rests on the support surface 24. A stop bar 27 on the blade holder 25 slides in a lug 28 on the blade carrier 22 and there is a collar 29 on the bar 27. There is a blade 30 fixed to a column part-31 of the blade holder 25.

The column 31 is an upstanding part of a housing in which a blade bar 32 is vertically mounted for sliding movement.

There is a blade 30 fixed to the upper end of the column 31 and a blade 33 at the top of the blade bar 32 combines with the blade 30 to provide a cutting pair to trim the end of a blind slat. The blade bar 32 is resilientlybiassed by a spring 32a within the housing to a lowered rest position.

Slidably mounted in the blade holder 25 in a horizontal direction there is a cam bar 34 with a lug 35 at one end and a cam face 36 at the other. The cam face 36 lies adjacent a cam roller 37 fixed to the blade bar 32. There is a slot 38 in the cam bar 34,and there is a pin 38a fixed to the blade holder 25 and engaged in the slot 38. There is a hydraulic piston and cylinder assembly or an 6 electric solenoid assembly, indicated generally 39, engaged with the lug 35.

Referring now to Fig.4 which is a first stage in the operation of the trimming blades. It will be noted that the pin 38a is at the right hand end of the slot 38. When the blade assembly is aligned with a slat, as will hereinafter be explained, the hydraulic assembly 39 is energised, a pull is applied to the lug 35. The cam bar 34 is prevented from moving relative to the blade holder 25 by the firm engagement of the cam roller 37 with the cam face 36, due to the action of the spring 32a. As a result the combination comprising the blade holder 25 and the cam bar 34 moves to the right until the collar 29 engages the lug 28. This will move the blade pair in an open condition from behind the slat to be trimmed to a position where the slat to be trimmed will be between the blades 30-33.

Continued pull on the lug 35 will now cause the cam bar 34 to move relative to the blade holder 25, as the blade holder cannot move any further because of the engagement between the lug 28 and the collar 29. The movement of the cam bar 34 will result in the Fig.5 arrangement where the cam face 36 has been forced under the cam roller 37 to push the blade bar 32 upwardly. The blade 33 is moved up to pass the blade 30 and the slat of the blind is trimmed. The length of movement of the cam bar 34, and thus the up movement of the blade bar 32 and the blade 33 thereon, is controlled by the engagement of the pin 38a 1 with the left hand end of the slot 38.

The return of the components to the Fig.4 configuration is possible by the action of the hydraulic unit 39 pushing against the lug 35 in combination with the action of the spring 32a. One blade carriage has an, associated slat detector which will control the down movement of the blade carriages to align the trimming blades accurately with a slat to be trimmed. This will be described later in the description of a working sequence of 10 the machine.

There are two cylindrical vertical posts 40 fixed at their lower ends to the base 5 and at their upper ends to inturned flanges 41 on the sides-3 and 4. A head rail support 42 with head rail clamping means 42ais provided with end bushes 44 which slidingly engage the posts 40. The head rail support 4.2 can be raised or lowered to accomodate blinds of different drops by means of endless chains 43 fixed to the bushes 44 and passing around uppet sprockets 45 - and lower sprockets 46 attached to shaft 47 drivable-by electric motor 48.

In a working sequence the motor 48 would be energised as required through the control panel 51 to raise or lower the head rail support 42 to ensure the blind to be trimmed can hang in an extended condition from the head rail support. The head rail 50 of the blind would then be clamped to the head rail support 42 by the clamps 42pL with the head rail central between the members 11 and 12, for 8 - 1 this purpose the head rail support 42 has a measuring means indicated 49.

The drive units 14 would then be energised from the control panel 51 to position the members 11 and 12 in the correct relationship with the blind, that is so that the blade assemblies are the correct distance in from the ends of the slats of the blind to provide the correct finished length for the slats. The motors 19 would then be energised from the control panel 51 to elevate the blade carriages to a position where the blade assemblies are aligned with the uppermost slat or slightly thereabove.

The machine is now ready to enter the automatic slat trimming phase but prior to this commen-.ing the bottom rail 52 of the blind is anchored by means of springs 53 or the like. In the automatic slat trimming operation the sequence is initiated from the control panel 51 and is as follows. The motors 19 operate in synchronous to lower the blade carriages until the slat detector turns the motors 19 off.

The slat detector can be for many kinds but one presently preferred detector will now be described. The preferred detector works on the basis of two light beams.

Referring now to Figs.6 to 8. In Fig.6 there is shown the ends of three slats S1, S2 and S2, there is a light beam housing fixed to the blade carriage 22. There are two light beams A and B about 4 mms apart which is narrower than the vertical spacing between two slats so it is impossible for 1 both beams to be cut simultaneously by two adjacent slats. In Fig.6 the light beam A is interrupted and the light beam B is not. The setting up of the light sensors is such that the combination, A cut - B not cut, will not turn off the motors 19 and the blade carriages will continue to lower. When the Fig.7 slat detecting arrangement occurs, that is B cut - A not cut, the motors 19 are turned off. The vertical positioning of the light housing and the cutting blades 30-33 is such that the blade pair 3033 can be moved forward and the slat S1 will lie between the blades 30-33 ready for trimming. When the motors 19 are turned off the sequence controller in the control panel moves to the next operation which is to activate the hydraulic assemblies 39 to move the cam bars 34 and the.blade holders 25 foward to perform a slat trimming operatioh as described above and then return the blade holders 25 to the rest positions.

The return of the blade holders 25 to the rest positions initiates the next operation in the sequence which is to energise the motors 1.9 to lower the blade carriages until the next time the beam B is interrupted and the beam A is not. The blade carriages are thus aligned with the next slat to be trimmed and the above sequence is repeated.

The foregoing is repeated continually until all slats are trimmed. When the last slat is trimmed and the blade carriages moves down the Fig.8 condition will be achieved, that is, both beams A and B are cut by the bottom rail which is thicker than the distance between the beams A and B. This can automatically stop the whole operation or, if desired, can be made to initiate the energisation of the motors 19 in the direction to raise the blade cxrriages until they are in line with the head rail 50 at which time the both beams will again be interrupted and this will cancel the cutting sequence through the controller 51.

After trimming the slats of the blind the head and bottom rails can be trimmed to length by placing the blind on the work table 6 and introducing the ends of the head and bottom rails into trimming devices, as indicated 54. The trimming 54 devices include sockets 57 and 58 the same shape as the head and bottom rails of the blind. The amount to be cut off can be judged by the machine operator and then guillotine blades 55 are raised by the piston and cylinder assembly 56 to cut material from the ends of the head and bottom rails whilst they are held firmly in the sockets 57 and 5 8.

The sequence controller suitably programmed can also be used to activate the drive units 14 to move the support members 11 and 12 to the required positions on the guides 7 and 8 when the required length measurement for the blind is keyed into an information bank forming part of the control unit. The raising of the head rail 50 of the blind could also likewise be automatically achieved from information input to the information bank.

11 V 4 1 1 - 11 1. A length trimming machine for the slats of an assembled and extended venetian blind comprising a head rail and a bottom rail connected by ladder tapes with slats supported in the ladder tapes, the machine comprising a head rail support, head rail clamping means on the head rail support, a bearing means at each end of the head rail support, two vertical posts respectively engaged in the bearing means, first drive means to raise and lower the head rail support on the posts, slat trimming means comprising two trimming units, each trimming unit including a blade carriage engaged with a carriage raising and lowering means, a blade assembly comprised of a pair of relatively movable slat trimming blades, the blade assembly is mounted on the P blade carriage so as to be movable horizontally on the blade' carriage between a restposition and work position where the blades are in cutting relationship with the slats of a blind mounted in the machine, means to move the blade pair between the rest and work positions and means to move the blades one relative to the other, a carriage support for each blade 20 carriage, each carriage support including a vertical track and a means to move its associated blade carriage along the vertical track, upper and lower horizontal guides each including a horizontal track, the upper and lower ends of the carriage supp orts are respectively engaged in the tracks of the upper and lower horizontal guides for movement - 12 therealong by carriage support moving means, and control means to selectively operate the first drive means, the means to move the blade pairs between the rest and work positions, the means to move the blades olie relative to the other, the means to move the blade carriages in the vertical tracks and the carriage support means in the tracks in the horizontal guides.

2. A machine as claimed in claim 1 wherein the means to move the blade carriages in the vertical tracks comprise threaded members engaged in threaded sockets in the blade carriages and electric motors to rotate the threaded members, with the blade pairs i n the rest positions the motors are able to be energised in response to an operations program in the control means, the motors are de-energised in response to sensing means which detects alignment of the blade pairs with a slat to be trimmed.

3. A machine as claimed in claim 1 wherein each blade assembly includes a blade holder mounted on a blade carriage so as to be movable in a horizontal direction between predetermined limits, a cam bar mounted in the blade holder so as to be movable in a horizontal direction relative to the blade holder within predetermined limits, a stationary blade mounted on a post on the blade holder, a blade mounted on a vertically movable bar in the blade holder, a cam face on the cam bar, a cam engaging member on the blade bar in i 1, r.

1 i 1 0 engagement with the cam face, means biassing the cam bar to a lowered position, an interconnection between the blade holder and the cam bar limiting the relative movement therebetween and means to apply force to the cam bar in the horizontal direction.

4. A machine as claimed in claim 3 wherein the means to apply force to the cam bar is a hydraulic assembly includinga piston and cylinder.

5. A machine as claimed in claim 1 wherein the means to raise and lower the head rail support comprises two endless chains around upper and lower sprockets, connections between the chains and the respective bearing means and a drive means for the chains.

6.' A machine.as claimed in claim 1 wherein the means.

to move the blade carriages along the tracks in the carriage supports.includes threaded rods rotated by reversible electric motors with the threaded rods engaged in threaded holes in the blade carriages.

A length trimming machine as hereinbefore described with reference to the accompanying drawings.

Published 1988 at The Patent Office, State Houre. 66'71 High Holborn, London WC1R 4TP. Further copies may be obtained from The Patent OMce, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd. St Mary Cray, Kent. Con. 1/87.