Stripping machines

Jan. 22, 1957

W. E. WALKER

STRIPPING MACHINES

2,778,286

Filed July 20, 1953

Sheets-Sheet 1

<img file="US2778286A_D0001.tif" />

INVENTOR william e. walker

BY

ATTORNEY

Jan. 22, 1957

W. E. WALKER

STRIPPING MACHINES

2,778,286

Filed July 20, 1953

Sheets-Sheet 2

<img file="US2778286A_D0002.tif" />

INVENTOR

WILLIAM E. WALKER

BY

ATTORNEY

United States Patent Office

2,778,286

Patented Jan. 22, 1957

2,778,286 STRIPPING MACHINES

William Edward Walker, Enfield, England

Application July 20, 1953, Serial No. 369,167

Claims. (Cl. 93—36)

This invention relates to stripping machines for stripping unwanted or waste material from cardboard and like material which has previously been cut and creased. The invention is chiefly useful in connection with cut and creased individual sheets but is also applicable when the cut and creased material is in continuous strip or web form.

Stripping machines in the past have been very expensive and inflexible. In one such machine one of a pair of driven rollers has secured in its surface pins which are located specially in accordance with the location of the unwanted material; the other roller, which, like the first is made of steel, has recesses cut out of the surface to receive the pins of the first roller. As will be appreciated, both rollers have to be made specially for stripping cut and creased material of any particular design and are useless when the design is changed; they are, therefore, used entirely for cut and creased material in strip or web form where the numbers of individual blanks to be made from the strip are very large, and justifies the large expense required for the stripping rollers.

When a small number of blanks are to be produced, it has been uneconomic to strip mechanically, and these are usually stripped by hand, a process that is timewasting and costly. No machines to our knowledge have been devised for stripping economically small numbers of blanks.

An object of the invention is thus to provide stripping means that are readily adaptable for stripping blanks of differing design, little modification being required to alter the machine for use with one design to use with another.

A stripping machine according to the present invention comprises a pair of cooperating rollers between which the blanks are fed and means adapted to be secured on one roller for holding in any selected position pins for piercing the unwanted material, the other roller having a surface which is sufficiently stiff to ensure that the blanks are gripped between and drawn through the rollers but is penetratable by the pins at any desired point in at least a part of the surface. This machine can be used with blanks both in sheet form and in strip or web form.

Preferably, the holding means comprises a tympan securable to the surface of the pin-holding roller and formed by a thin metal sheet perforated at narrowly spaced regular intervals, the pins being insertable through any of the perforations.

The pin-receiving roller preferably has a surface consisting of a wire brush or engineers file-card. However, other materials may be used such as stiff sponge rubber into which the pins can penetrate without unduly damaging the material and which is stiff enough to cooperate with the pin-holding roller to grip and draw the blanks therebetween.

The invention will be more readily understood by way of example from the following description of a stripping .40 machine in accordance therewith, reference being made to the accompanying drawings, in which:

Figure 1 is a front view of the stripper;

Figure 2 is a section on the line II—Π of Figure 1;

Figure 3 is a section on the line III—III of Figure 2, and .

Figure 4 is a section similar to Figure 2 on an enlarged scale, showing a pin in position.

The stripper comprises two driven wooden rollers 12, 13 mounted one above the other at the delivery end of the blank cutting and creasing machine. The upper or pin-receiving roller 13 has its surface almost entirely covered by a length of engineers file-card or wire brush 14 which is arranged as shown in Figure 2 with the wires located pointed radially outwards. The lower or pinholding roller 12, on the other hand, carries a tympan of perforated metal sheet 15. Roller 12 has a sector 16 cut therefrom; to the walls of this sector are secured the ends of the sheet 15 with, beneath the sheet 15, a card underlay 17 and a paper backing sheet 18. The sheet 15 and the layers 17, 18 underneath are held in place by screws 19 threaded into holes in the roller 12.

The sheet 15 is of 24 S. W. G. and the perforations therein are approximately 0.080 in diameter arranged in a square pattern of approximately W pitch. Through selected perforations are passed, before the sheet is secured on the roller 12, pins 20, the heads of the pins being located on the inner side of the sheet 15 and accommodated in the underlay 17. The shanks of pins 20 thus project radially outwardly from the roller 12.

While the cutting and creasing machine is being prepared for a new job, the tympan 15 and the underlayers 17 and 18 are removed from roller 12 and pins 20 located in perforations in tympan 15 corresponding to the position of the waste or unwanted material in the new blanks. The tympan and underlayers are then replaced on the roller 12. Alternatively, a second tympan can be prepared, during use of a first tympan, with the pins in appropriate position for the next job. On change-over, the second tympan is merely substituted on roller 12 for the first which is stored for reuse if required.

The blank 21 which is fed from the cutting and creasing machine is seized in the bite of the rollers 12 and 13 and drawn therethrough, the separation of the rollers . 12, 13 being such that the blank is firmly caught by the surfaces thereof without unduly bending and damaging the file-card 14. During passage of the blank 21 through the rollers, the pins 20, which have been specially positioned for this purpose, pentrate the unwanted or waste parts 22 of the blank and hold those parts to the surface of tympan 15. The wanted parts 23 of the blank 21 on the other hand are not so held by pins 20 and move tangentially with respect to the rollers, being seized and removed by the pair of conveyor rollers 35.

To remove the unwanted material from the pins 20 after separation from the blank, a comb 24 is mounted adjacent the surface of the roller 12 beneath the bite of the rollers. The teeth 25 of the comb 24 are chamfered to edges located very near to the surface of the tympan 15 so as to enter between the unwanted material 22 and the tympan, and remove the unwanted material 22 from the pins 20. The teeth 25 are spaced apart at separation to permit the pins 20 to pass undamaged between them.

At high speeds of the rollers 12, 13 there is a tendency for the wanted material 23 to cling to the tympan 15 on leaving the bite of the rollers, with the result that it is not grasped and removed by rollers 35. To avoid this, there is provided in an axial slot 25 in roller 12, a bar 26 projecting at each end from roller 12 and carrying at either end a cam roller 27. Cam rollers ‘

2.778.286 travel in stationary cam tracks 28 located at each side of the roller 12. At spaced axial intervals in the roller 12 are radial slots 29, each opening at one end to the surface of roller 12 and at the other end to slot 25. These slots 29 are aligned with threaded holes 30 in the bar 26 and with holes in the tympan 15 and underlayers 17, 18. According to the location of the wanted material 23 in the blank 21, plungers 31 are screwed into selected holes 30.

Cam tracks 28 are circular over the larger parts of their lengths and the plungers 31 are thereby held retracted within the roller 12 and do not foul the comb 24. However, when the plungers pass under the bite of the rollers, the cam tracks cause the plungers to project outwardly from the roller and the outer ends of the plungers to follow for a short distance a tangential and horizontal path with respect to the roller. The plungers 31 are selectively located to engage, when they project in this way, only the wanted parts of the blank and to cause these parts to be forced away from the tympan 15 so as to ensure that the leading edges are seized by the rollers 35. The cam track then causes the plungers 31 to retract before they reach the comb 24.

Where the speed of rollers 12, 13 is small, it may be found that the plungers 31 can be dispensed with. Alternatively, other means for pressing the wanted material away from the roller 12 may be used, such as sponge rubber pads located on the surface of the tympan 15 or spring fingers so mounted, the comb 24 being recessed to allow the pads or fingers to pass. The pads or fingers will force the wanted material away from the roller.

The rollers 12, 13 are driven through meshing gear wheels 33, 34 at the same peripheral speed. These gear wheels may be driven by the cutting and creasing machine or by an independent motor, although the former is preferred as synchronism is then more easily attained.

As has been explained, the configuration of pins 20 in tympan 15 can quickly be changed to suit varying designs of blank, merely by removing the tympan from the roller 12 and locating the pins in different perforations suited to the shape of the waste material of the new design. Similarly, the positioning of plungers 31 can be quickly altered to suit a new design of blank. By virtue of the nature of file-card 14 on roller 13, pins 20 will be received by the upper roller 13, whatever their positions without undue damage to the file-card and accordingly the upper roller does not have to be altered at all when the blanks to be stripped are changed in design. Altogether, changeover of the stripper can be effected quickly and with ease.