GB1593484A

GB1593484A - Feed apparatus for intermittently feeding sheet material

Info

Publication number: GB1593484A
Application number: GB16441/78A
Authority: GB
Original assignee: Schweizerische Industrie Gesellschaft
Current assignee: Schweizerische Industrie Gesellschaft
Priority date: 1977-05-27
Filing date: 1978-04-26
Publication date: 1981-07-15
Also published as: DE2813155A1; IT1107159B; IT7867970A0; CH614673A5

Abstract

The printed foil (3) is drawn from a stock roll (4) in steps by a gripper (2) over a table (1). The foil (3) has markings (6) which correspond to the spacing (t) of the printed pattern and which influence a photoelectric sensing head (7). A roller (9) serving as a retraction member for the foil can engage to a greater or lesser depth into a transverse gap (19) of the table (1). The roller (9) is connected via a linkage (13, 14) to an armature plate (42) which is pulled up by an electromagnet (36) when the latter is energised. During each feedstroke, the foil (3) is drawn forwards by the gripper (2) over a length (v) which is greater than the spacing (t). The roller (9) is then actuated and retracts the foil until a marking (6) influences the sensing head (7), the latter energising the electromagnet (36). The movement of the roller (9) is thereby stopped immediately. The feed apparatus allows an accurate feed and works virtually free of wear. <IMAGE>

Description

(54) FEED APPARATUS FOR INTERMITTENTLY FEEDING SHEET MATERIAL (71) We, SIG SCHWEIZERISCHE INDUSTRIE-GESELLSCHAFT, a Swiss body corporate, of 8212 Neuhausen am Rheinfall, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to apparatus for intermittently feeding sheet material printed with a repeat pattern.

In a known apparatus, the material is advanced by means of a feed element by a feed stroke exceeding the pattern repeat and is retracted by means of a retraction element, a scanning head being provided which responds to marks on the material to control energisation or de-energisation of a winding of an electromagnetic unit to arrest the retraction element, and a cutter being provided for successively cutting off portions of the positioned material.

Such apparatus may be used for packaging purposes. In a known apparatus of this type, the retraction element is pivotably journalled and is firmly connected to a gear wheel sector co-operating with a pawl which engages in a tooth gap of the sector when the electromagnet is energised. Consequently, the retraction element may only be stopped in any one of a number of stages corresponding to the tooth pitch; since, moreover, the toothed sector and the pawl are subject to heavy wear, time-consuming readjustments to the apparatus are often necessary.

According to the invention there is provided feed apparatus for intermittently feeding sheet material printed with a repeat pattern, said apparatus comprising feed means arranged to advance the material by a feed stroke exceeding the pattern repeat, retraction means for retracting the material by a positioning stroke, a scanning head for sensing markings on the material an electromagnetic unit res ponsive to the scanning head to arrest the retraction means by means of an armature plate of magnetizable material connected tc the retraction means and arranged opposite the electromagnetic unit such that upon ener gisation or de-energisation respectively of a winding of the unit, the armature plate is stopped by and urged against the unit to brake the retraction means, and a cutter for successively cutting off portions of the positioned sheet material.

The invention is described further, by way of example with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal section of feed apparatus along the line I-I of Fig. 2, Fig. 2 is a plan view of the apparatus of Fig. 1, Fig. 3 is a cross-section through the apparatus along the line III--III of Fig. 2, Fig. 4 is a detail of a variant in section along the line IV-IV of Fig. 5, and Fig. 5 is a section through the variant along the line V-V of Fig. 4.

The illustrated apparatus has a table 1 over which printed foil 3 may be drawn from a supply roller 4 by means of a double clamp 2. In the vicinity of the downstream end of the table 1 a cutter 5 is disposed for cutting off a piece 3a of the foil 3 whose length t is equal to the repeat of the printed pattern of the foil. The portions 3a are used for packing articles and the present invention aims to ensure that all the portions 3a are identically printed; whereby displacement of the pattern, which is the result if all the portions 3a are slightly larger or smaller than the repeat t and which gives rise to cumulative error, is avoided. For correctly spaced positioning of the portions 3a relative to the clamp 2 and the cutter 5, markings 6 are provided in a known manner at one edge of the foil 3, with one marking 6 in fact on each portion 3a. The clamp 2 advances the foil 3 in each working cycle by a feed stroke v which is greater than the length t; the cutter 5 is then actuated and the foil 3 is pulled back in a manner described later in detail by a positioning stroke z until the trailing edge of the marking 6 ef the next portion 3a passes under a light beam 8 formed by a photoelectric scanning head 7 when the backward movement of the foil 3 is complete.

After the cut foil portion 3a has been removed in a manner which is not shown for supply to a packing machine, the clamp returns into the collecting position 2' (shown by dash-dct lines) and a new working cycle begins.

To effcct the positioning stroke z, a retraction roller 9 is provided which is mounted on an axle 10 whose ends are supported in bearings 11 and 12 provided at the ends of two arms 13 and 14 which are fixed on a common pivot axle 15. The arm 14 is loaded downwards by a tension spring 17 held firmly on a pin 16 which is fixed on a frame wall 18.

Below the retraction roller 9 an elongate transversely extending opening 19 is provided in the table 1, into which opening the roller 9 draws the foil 3 when permitted to submit to the reaction of the spring 17. Projecting upwards through another opening 20 in the table 1 is an arm 21 which is rigidly connected to the arm 14 and which carries a roller 22 on its upper end. A cam 23 is fixed on an axis 24 which is journalled in a framemounted bearing 25 and is provided with an actuating lever 26 which is pivoted to and fro by means (not shown) in the working cycle of the apparatus. When the lever 26 pivots in the direction of the arrow 27, the cam 23 contacts the roller 22 so that the axle 15 is pivoted in the direction of the arrow 28 and the roller 9 is raised into the position 9'. When the cutter 5 has cut the portion 3a, the lever 26 is pivoted in the direction of the arrow 29 so that the roller 9 is moved downwards under the action of the spring 17 and the foil 3 is drawn into the gap 19.

So that, in so doing, only the downstream end of the foil 3 is pulled backwards, a braking finger 30 is provided which is urged by a torsion spring 31 so strongly against the trailing part of the foil 3 that this part is clamped onto the table 1 and only submits to the stronger pull of the clamp 2 and not to the much smaller pull exerted when the roller 9 is lowered. A clamping roller 32 is in addition provided between the table 1 and the supply roller 4.

When as a result of lowering the roller 9 the, for example, black marking 6 reaches the light beam 8, which is formed in a known manner by a beam of light coming from the scanning head and a beam reflected backwards into the latter, the downward movement of the roller 9 is instantly stopped. For this purpose, the output signal of the photoelectric scanning head 7 is supplied by way of a line 33 to an amplifier 34 whose output current energizes the winding 35 of an electromagnet 36. The scanning head 7 is fixed by means of a holder 37 to the frame wall 18 while the amplifier 34 is mounted directly on said wall and the electromagnet 36 is fixed by a holder 38 on the table 1. The axle 15 of the levers 13 and 14 is journalled in a bearing 39 fixed under the table 1. In the vicinity of the axle 15 the lever 13 has a lug 40 on which an armature plate 42 of magnetizable material is rigidly fixed by means of two screws 41 in a position opposite the electromagnet 36.

Between the armature plate 42 and the electromagnet 36 there is a very small gap s which may be, for example, only 0.lmm.

Between the bearing 39 and the lever 14 and between the roller 9 and the bearing 12 there is sufficient clearance to allow a transverse movement of the levers 13 and 14 by the small amount s in the event of this amount not being absorbed by the resilience of the unit.

It is clear that, when the electromagnet 36 is energised, it firmly brakes the armature plate 42 which prevents further pivoting of the levers 13 and 14 and further lowering of the roller 9, i.e. the positioning stroke z is terminated. A non-magnetizable friction lining which may be made, for example, of 0.2mum thick brass or nylon is preferably provided between the body of the electromagnet 36 and that of the armature plate 42. This has the advantage that, after the electromagnet 36 has been energised, the armature plate 42 does not tend to remain held to the electromagnet. The friction lining may be secured on the body of the electromagnet 36 or that of the armature plate. It is also stressed that the electromagnet, which brakes the armature plate 42 by urging it in a direction parallel to the axles 10 and 15, has a radial clearance r from the axle 15 which promotes accurate stopping of the roller 9.

A known feed apparatus also uses an electromagnet to stop downward motion of a retraction roller but in that apparatus, however, there is connected to a pivot axle of the roller a gear wheel sector which is engaged by a pawl when an electromagnet is energised.

This not only has the disadvantage that stopping may not occur in any position of the retraction roller but only in any one of a number of stages corresponding to the tooth pitch, but also has the disadvantage that because of the impact stress on the pawl and the gear wheel sector these are subject to extreme wear which may produce additional inaccuracies in positioning portions to be severed from the foil, i.e. a variation in the required positioning stroke z. To ensure correct operation of the positioning device cf this known apparatus, very careful and expensive monitoring and servicing and possibly subsequent adjustment to the individual parts of the device is therefore necessary. In comparison, the present apparatus by virtue of the continuous surface contact possible between the armature plate 42 and the electromagnet 36, offers higher operational reliability with a reduced construction and servicing outlay even under unfavourable working conditions such as, for example, weak foils, poor printing quality, foils where the spacing of the markings is not adhered to correctly, sharp changes in speed, i.e. in working tempo, which may influence the clamp stroke etc.

Figs. 4 and 5 show a variant in which the retraction roller 9 is firmly braked not on energisation but on de-energisation of an electromagnet winding. In this example, there is fixed on the holder 38 a magnetic unit 43 composed not of two but of three components, namely a permanent angular magnet 44, a body 45 made of magnetizable material and an electromagnet winding 46. Instead of the armature plate 42, a holding plate 47 of non-magnetizable material is fixed by means of the screws 41 on the lug 40. Three leaf springs 49 are secured at one end to the plate 47 by means of screws 48 and carry pins 50 on their other ends. Each pin 50 is fixed by means of a respective nut 51 to a circular armature plate 52 of a magnetizable material and is provided with a cylindrical guide head 53 which is movable within a respective hole 54 in the plate 47 in a direction perpendicular to said plate. The nuts 51 are located in recesses in the armature plate 52 so that the latter fully contacts the magnetic unit 43 when braked thereby. The leaf springs 49 tend to pull the armature plate 52 away from the magnetic unit 43, i.e. into the position of Fig. 5. The permanent magnet 44 attracts the armature plate 52 but cannot overcome the force of the springs 49 as long as the winding 46 is energised because the winding counteracts the permanent magnet 44. When the current is not flowing in the winding 46 which-in contrast to the embodiment of Figs. 1 to 3--occurs when one of the markings 6 passes under the light beam 8, the unit 43 halts the armature plate 52 and therefore firmly brakes the axle 15 and the retraction roller 9. This braking occurs more quickly than in the earlier described embodi ment because the reduction of the magnetic field of the winding 46 is faster than the build-up of the magnetic field of the winding 35. The previously mentioned clearance for the transverse movement of the levers 13 and 14 is, moreover, no longer necessary.

It should be mentioned that basically cutting may take place in the working cycle after positioning instead of before though this is generally less advantageous because there is then less time to advance the cut foil portion before the return stroke of the clamp. It should also be mentioned that instead of the clamp 2 friction rollers could be provided as a feed and that a vertically adjustable roller need not necessarily be provided as a retraction element. Also, in place of a photoelectric scanning head, a scanning head of another type, e.g. a magnetic scanning head could be provided but this would adversely affect the simplicity of the markings. The apparatus could also be constructed in such a manner that, when the electromagnet 36 is energised, it is not the armature plate 42 which moves but the electromagnet 36 which pivots slightly relative to the frame.

THAT WE CLAIM IS:- 1. Feed apparatus for intermittently feed ing sheet material printed with a repeat pat tern, said apparatus comprising feed means arranged to advance the material by a feed stroke exceeding the pattern repeat, retraction means for retracting the material by a posi tioning stroke, a scanning head for sensing markings on the material, an electromagnetic unit responsive to the scanning head to arrest the retraction means by means of an armature plate of magnetizable material connected to the retraction means and arranged opposite the electromagnetic unit such that upon ener gisation or de-energisation respectively of a winding of the unit, the armature plate is stopped by and urged against the unit to brake the retraction means and a cutter for successively cutting off portions of the posi tioned sheet material.

2. Apparatus as claimed in claim 1, in which the retraction means comprises a roller whose axis is disposed perpendicular to the feed direction and which is pivotable about a spaced axis by means of two levers, the armature plate being connected to one of the levers and being stoppable up by the electromagnetic unit in a direction parallel to the roller axis.

3. Apparatus as claimed in claim 2, in which the armature plate is rigidly connected to said one lever and the unit is arranged to stop the armature plate on energisation of the winding.

4. Apparatus as claimed in claim 2, in which the armature plate is connected for movement in a direction parallel to the roller's axis by spring elements and guide elements to a holding plate of non-magnetizable material which is in turn connected rigidly to said lever the unit being arranged to stop the armature plate on de-energisation of the winding.

5. Apparatus as claimed in claim 2 or 3, in which the unit has a radial clearance from said spaced axis.

6. Apparatus as claimed in claim 2, 3 or 5, in which a friction lining of nonamagnetizable material is provided between the body of the unit and that of the armature plate.

7. Apparatus as claimed in claim 3, in which an axial clearance is provided between the roller and the roller mountings which clearance is greater than spacing between the armature plate and the unit when the winding of the unit is not energised.

8. Apparatus as claimed in claim 4, in which the unit comprises a permanent magnet, a body of magnetizable material and said winding, the latter in its energised state counteracting the permanent magnet.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

which may influence the clamp stroke etc.

Figs. 4 and 5 show a variant in which the retraction roller 9 is firmly braked not on energisation but on de-energisation of an electromagnet winding. In this example, there is fixed on the holder 38 a magnetic unit 43 composed not of two but of three components, namely a permanent angular magnet 44, a body 45 made of magnetizable material and an electromagnet winding 46. Instead of the armature plate 42, a holding plate 47 of non-magnetizable material is fixed by means of the screws 41 on the lug 40. Three leaf springs 49 are secured at one end to the plate 47 by means of screws 48 and carry pins 50 on their other ends. Each pin 50 is fixed by means of a respective nut 51 to a circular armature plate 52 of a magnetizable material and is provided with a cylindrical guide head 53 which is movable within a respective hole 54 in the plate 47 in a direction perpendicular to said plate. The nuts 51 are located in recesses in the armature plate 52 so that the latter fully contacts the magnetic unit 43 when braked thereby. The leaf springs 49 tend to pull the armature plate 52 away from the magnetic unit 43, i.e. into the position of Fig. 5. The permanent magnet 44 attracts the armature plate 52 but cannot overcome the force of the springs 49 as long as the winding 46 is energised because the winding counteracts the permanent magnet 44. When the current is not flowing in the winding 46 which-in contrast to the embodiment of Figs. 1 to 3--occurs when one of the markings 6 passes under the light beam 8, the unit 43 halts the armature plate 52 and therefore firmly brakes the axle 15 and the retraction roller 9. This braking occurs more quickly than in the earlier described embodi ment because the reduction of the magnetic field of the winding 46 is faster than the build-up of the magnetic field of the winding 35. The previously mentioned clearance for the transverse movement of the levers 13 and

14 is, moreover, no longer necessary.

It should be mentioned that basically cutting may take place in the working cycle after positioning instead of before though this is generally less advantageous because there is then less time to advance the cut foil portion before the return stroke of the clamp. It should also be mentioned that instead of the clamp 2 friction rollers could be provided as a feed and that a vertically adjustable roller need not necessarily be provided as a retraction element. Also, in place of a photoelectric scanning head, a scanning head of another type, e.g. a magnetic scanning head could be provided but this would adversely affect the simplicity of the markings. The apparatus could also be constructed in such a manner that, when the electromagnet 36 is energised, it is not the armature plate

42 which moves but the electromagnet 36 which pivots slightly relative to the frame.

THAT WE CLAIM IS:- 1. Feed apparatus for intermittently feed ing sheet material printed with a repeat pat tern, said apparatus comprising feed means arranged to advance the material by a feed stroke exceeding the pattern repeat, retraction means for retracting the material by a posi tioning stroke, a scanning head for sensing markings on the material, an electromagnetic unit responsive to the scanning head to arrest the retraction means by means of an armature plate of magnetizable material connected to the retraction means and arranged opposite the electromagnetic unit such that upon ener gisation or de-energisation respectively of a winding of the unit, the armature plate is stopped by and urged against the unit to brake the retraction means and a cutter for successively cutting off portions of the posi tioned sheet material.
2. Apparatus as claimed in claim 1, in which the retraction means comprises a roller whose axis is disposed perpendicular to the feed direction and which is pivotable about a spaced axis by means of two levers, the armature plate being connected to one of the levers and being stoppable up by the electromagnetic unit in a direction parallel to the roller axis.
3. Apparatus as claimed in claim 2, in which the armature plate is rigidly connected to said one lever and the unit is arranged to stop the armature plate on energisation of the winding.
4. Apparatus as claimed in claim 2, in which the armature plate is connected for movement in a direction parallel to the roller's axis by spring elements and guide elements to a holding plate of non-magnetizable material which is in turn connected rigidly to said lever the unit being arranged to stop the armature plate on de-energisation of the winding.
5. Apparatus as claimed in claim 2 or 3, in which the unit has a radial clearance from said spaced axis.
6. Apparatus as claimed in claim 2, 3 or 5, in which a friction lining of nonamagnetizable material is provided between the body of the unit and that of the armature plate.
7. Apparatus as claimed in claim 3, in which an axial clearance is provided between the roller and the roller mountings which clearance is greater than spacing between the armature plate and the unit when the winding of the unit is not energised.
8. Apparatus as claimed in claim 4, in which the unit comprises a permanent magnet, a body of magnetizable material and said winding, the latter in its energised state counteracting the permanent magnet.
9. Fecd apparatus arranged substantially

as herein particularly described with reference to and as illustrated in Figs. 1 to 3; or Figs. 1 to 3 when modified by Figs. 5 and 6 of the accompanying drawings.