US3682471A

US3682471A - Device for extracting blanks from a stack

Info

Publication number: US3682471A
Application number: US53555A
Authority: US
Inventors: Bruno Pahlitzsch
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-07-17
Filing date: 1970-07-09
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08
Also published as: GB1308373A; DE1937080B2; DE1937080A1

Abstract

A device for extracting blanks, which are to be formed into envelopes, one at a time from a stack of blanks comprises a first lever device with a suction nozzle which engages the bottommost blank by suction and bends one edge of the blank downwardly. A second lever device operates a plunger to insert the plunger between the bent down edge of the bottommost blank and blanks thereabove, and a third lever device which operates a device to lift the blanks above the bottommost blank off the bottommost blank so that the latter can be extracted by means of a rotating roller. All three lever devices have respective cam follower rollers which engage in a single elliptical cam track groove in one face of a disc cam which is rotatable about an axis, the groove being eccentric to the axis.

Description

United States Paten Pahlitzsch [4 1 Aug. 8, 1972 [S4] DEVICE FOR EXTRACTING BLANKS FROM A STACK [72] Inventor:

I 67, Berlin, Germany [22] Filed: July 9, 1970 [21] Appl. No.: 53,555

[30] Foreign Application Priority Data July 17, 1969 Germany ..P 19 37 080.0

52 U.S. c1..... ..271/29 51 in. C1 ..B65h 3/10, B65h 3/50 [58] Field 61 Search ..271/29, 32, 23

[56] References Cited UNITED STATES PATENTS 3,380,353 4/1968 Mitterrnayer ..-..271/29 x 3,008,706 11/1961 Heigl et al ..271/29 x 3,567,559 3/1971 Dullinger ..271/29 x 2,954,225 9/1960 Novick ..271/29 x Bruno Pahlitmch, Gneisemaustrasse I Primary Examiner-Joseph Wegbreit Assistant Examiner-Bruce H. Stoner, Jr.

Attorney-Karl E. Ross ABSTRACT A device for extracting blanks, which are to be formed into envelopes, one at a time from a stack of blanks comprises a first lever device with a suction nozzle which engages the bottommost blank by suction and bends one edge of the blank downwardly. A second lever device operates a plunger to insert the plunger between the bent down edge of the bottommost blank and blanks thereabove, and a third lever device which operates a device to lift the blanks above the bottommost blank off the bottommost blank so that the latter can be extracted by means of a rotating roller. All three lever devices have respective cam follower rollers which engage in a single elliptical cam track groove in one face of a disc cam which is rotatable about an axis, the groove being eccentric to the axis.

8 Clains, 4 Drawing Figures PATENTEDAUB M 7 3,682,471 SHEET 3 BF 4 mvenior:

bHLIIO 53 .51.-- Q; iii

PATENTEDAUG 8 i972 3,682,471

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DEVICE FOR EXTRACTING BLANKS FROM A STACK FIELD OF THE INVENTION The present invention relates to a device for extracting the bottommost one of a stack of blanks of sheet material such for example as blanks for envelopes, bags or the like.

BACKGROUND OF THE INVENTION In the automatic production of envelopes, one known method commences with pre-cut envelope blanks which are stacked one above the other and placed thus in the machine for manufacturing the envelopes. In so doing, the individual blanks are successively drawn from the bottom of the stack and supplied to a conveyor path upon which all the operations required to convert the blank into a finished envelope or bag, are carried out. In the known system, in order to withdraw the bottommost blank of the stack, three successively operating lever devices are used, one of which carries a suction device, the other a plunger and the third two stack lifters with air-blast nozzles. In withdrawing the blank, firstly the front edge is gripped by the suction device and bent downwards. Into the space thus opened between the bottommost blank and the stack, a plunger is inserted which keeps the front edge of the stack in position. Then, into said same space, the stack lifters, which are equipped with airblast nozzles, are introduced. By means of the air-blast the bottommost blank is separated, with the assistance of the lifting of the stack, so that this blank can be withdrawn freely. In this known embodiment, the time sequence and time of operation of the individual lever devices, are controlled by three cams. The use of three separate such cams for the three lever devices makes for substantial constructional outlay; also, the provision of these cams necessitates a larger installation space. Finally, a further drawback of this arrangement resides in the fact that the cams, which must be precisely adjusted in relation to one another, tend over long periods of operation to become slightly out of phase with one another so that the time relationship between the operations of the individual lever devices is changed, leading thus inevitably to faulty operation.

OBJECT OF THE INVENTION The object of the present invention is to avoid these drawbacks and create a device which is distinguished by minimal constructional and installational outlay, and in which alteration in the mutual positions of the lever devices, is excluded.

SUMMARY OF THE INVENTION According to the invention there is provided a device for extracting the bottommost one of a stack of blanks of sheet material, comprising a lever device adapted to bend down a front end of the bottommost blank and including a suction nozzle, a lever device connected to a plunger adapted to be inserted between the bent down edge of the bottom blank and the stack, and an additional lever device carrying stack lifter means with at least one air-blast nozzle, a common, closed path cam system being provided to control all the lever devices in respect of operating sequence and time of operation.

Preferably the closed path of the cam system consists of an elliptically-shaped cam track groove disposed in a rotating disc eccentrically vis-a-vis the disc center, which cam track is disposed symmetrically vis-a-vis a plane perpendicular to the disc and passing through the center of rotation, follower rollers located at free ends of the lever devices being guided in said cam track groove at distances from one another.

Preferably, follower rollers of the lever devices carrying the stack lifters with the air-blast nozzles, and carrying the plunger, are located diametrically opposite one another in the cam track and the third follower roller is located between them, proximal to the follower roller associated with the stack lifters.

The above-mentioned disc containing the cam track is advantageously arranged in a closed housing, and free ends of levers carrying the follower rollers are carried in bearings arranged in the housing. Also a toothed sector may be attached to a free end of each lever carrying a follower roller, each sector being in engagement with a gear, the gears respectively controlling the movements of suction nozzle, plunger and stack lifters.

Finally, the plunger is preferably arranged for longitudinal displacement in a mounting secured to the housing, and is formed at its end as a rack which engages with a gear; the gear associated with the rack and that associated with a cam-operated lever each carry a radial arm, the two arms being attached to one another by a link.

DESCRIPTION OF THE DRAWING The accompanying drawing illustrates an example of a device in accordance with the invention. In the drawing:

FIG. 1 schematically illustrates an assembly drawing; FIG. 2 is an illustration in accordance with FIG. 1 in which only the lifter mechanism for the front edge of the bottom blank in the stack, has been shown;

FIG. 3 is an illustration in accordance with FIG. 1 in which only the lever device operating the plunger, has been illusrtated; and

FIG. 4 is an illustration in accordance with FIG. 1 in which only the lever device operating the stack lifters, has been shown.

SPECIFIC DESCRIPTION FIG. 1 illustrates a stack 1 consisting of stacked blanks of sheet material. Beneath the stack an extraction roller 2 is arranged. Also arranged near the stack is a closed housing 3 in which a disc cam 4 rotates, the cam containing a cam-track groove 5 in which there are engaged three levers, namely, a lever 8 for a device for bending down the bottommost blank, a lever 17 for a plunger 31 and a lever 31 for a stack lifter. All the bearings for the cam 4 and three lever devices are arranged on the housing 3. For purposes of clarity of illustration, FIGS. 2 to 4 each illustrate one of the three lever devices.

As FIG. 2 shows, the lever 8 is guided by means of a follower roller 9 in the cam track 5. The lever 8 is rotatable upon a shaft 10 and has attached to it a toothed sector 7 which meshes with a gear 12 carried on a spindle 13. The gear 12 carries an arm 14 which, at its other end, carries a suction head 15 with the suction nozzle 16; when the disc cam 4 is rotated in the clockwise direction, said lever 8 is pivoted upwards about the shaft 10, the sector 11 moving towards the left. Consequently, the gear 12 is rotated counterclockwise and in so doing pivots the arm 14, with the suction head 15, downwards so that the front edge of the blank located buttommost in the stack 1, is bent downwards.

Then, as FIG. 3 shows, the plunger 31 enters the space between the stack and the edge of the bottom blank. To this end, the lever 17 is guided by means of a follower roller 18 in the cam track 5. The lever 17 is arranged upon a shaft 19 and is connected to a toothed sector 20 which meshes with a gear 21 mounted on a spindle 22 and carrying an arm 23, the latter being linked by a link 24 to an arm 25 which is rotatably mounted on a shaft 26 and secured to a gear 27 meshing with a toothed rack 30 of. a plunger rod 28. The plunger rod 28 is mounted in a longitudinally displaceable manner in a guide 29. At its front end it carries the plunger 31. When the externally located crest of the track reaches the follower roller 18 during the course of the clockwise rotation of the cam disc 4, the lever 17 is pivoted downwards and then upwards, the toothed sector connected to it rotates towards the right and then the left about the spindle 19, the gear 21 is rotated counterclockwise and then clockwise around the spindle 22, and the arm 23, the link 24 and the arm are moved towards the left and then the right so that the gear 27 engaging with the rack 30 of the plunger rod 28 displaces said rod 28 in the guide 29 towards the right and then the left with the consequence that the plunger 31 penetrates into the space between the stack and the bottommost blank.

With further rotation of the disc cam 4 in the clockwise direction, the lever mechanism of the stack lifter (FIG. 4) comes into operation. To this end, a lever 32 engages the cam track 5 by means of a follower roller 33, lever 32 being pivotable about a spindle 34 and carrying a toothed sector 35 engaging with a gear 36, the latter in turn meshing with a gear 37. The gear 37 carries an arm 38 at whose end, lifters 39 are located, the latter being provided at their top surfaces with air-blast nozzles 40. When the plunger 31 has penetrated into the space between stack and bottommost blank, in the manner shown in FIG. 3, with further rotation of the disc cam 4, the lever 32 is pivoted upwards and then downwards so that the toothed sector 35 attached to it moves towards the left and then the right and the gear 36 is rotated clockwise and. then counterclockwise. The gear 37 is rotated counterclockwise and then clockwise by the gear 36 so that the arm 38 secured to said gear 37 and carrying the lifters 39, enters the space opened up by the plunger 31, the air-blast nozzles 40 located on the topside of the lifter 39 lifting the stack away from the bottom blank so that the latter can be withdrawn freely by the extraction roller 2 and conveyed to a conveyor.

The drive to the disc cam 4 is effected through a gear 6 driven by the machine.

By the provision in accordance with the invention, of a single cam disc containing a cam track (groove), which disc is arranged in a closed housing also containing the three lever devices, a compact, closed construction is obtained. Because all three lever devices are guided in one and the same cam track and are mounted in a fixed housing, mutual alteration of the settings of the three lever arrangements is out of the question so that they are always operated in the same timed relationship. The closed design of the housing prevents any ingress of dust and impurities so that the device in accordance with the invention operates completely reliably. Indeed, the cam can be arranged to operate in an oil bath. By the design of the cam track as a groove, the heavy duty tension and compression springs required in association with conventional cams in order to maintain the levers in continuous engagement with the cam tracks, are obviated. Furthermore, the device in accordance with the invention ensures quieter and more rapid running.

I Claim:

1. Apparatus for supporting a stack of blanks of sheet material one on top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction nozzle and operable to engage the nozzle with the bottommost blank in the stack and bend down one edge of said bottommost blank;

a second lever device operatively connected to a plunger and operable to insert the plunger between the bent down edge of said bottommost blank and blanks above the bottommost blank;

a third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack;

a rotatable single track cam device;

first, second and third cam-follower means engageable with the single track of said cam device and operatively connected to said first, second and third lever devices respectively;

and drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device.

2. Apparatus for supporting a stack of blanks of sheet material one on top of another and for separatinga bottommost blank in the stack from other blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction nonle and operable to engage the nozzle with the bottommost blank in the stack and bend down one edge of said bottommost blank;

a rotatable cam device;

first, second and third cam-follower means engageable with said cam device and operatively connected to said first, second and third lever devices respectively;

and drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device, said rotatable cam device comprising a disc which is rotatable about an axis and is formed with an elliptical groove in one face of the disc, said groove being eccentric to said axis and said first, second and third cam follower means all engaging in said groove.

3. Apparatus as defined in claim 2 wherein said second and third cam follower means are arranged substantially diametrically opposite each other relative to said axis.

4. Apparatus for supporting a stack of blanks of sheet material one one top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

-a third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack;

a rotatable cam device;

drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device; and

a closed housing and bearing means within said housing carrying said first, second and third lever devices and cam follower means within said housing.

5. Apparatus for supporting a stack of blanks of sheet material one on top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction 'noule and operable to engage the nozzle with the bottommost blank in the stack and bend down one edge of said bottommost blank;

a rotatable cam device;

first, second and third cam-follower means engageatommost blank in the stack from other blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

21 third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack;

a rotatable cam device;

drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device;

guide means guiding said plunger for longitudinal displacement of said plunger;

a toothed rack member connected to said plunger, and a first gear in mesh with said toothed rack member, said second lever device comprising a first lever connected to said first gear;

a link member pivotally connected to said first lever;

a second lever pivotally connected to said link member;

a second gear connected to said second lever;

a toothed sector in mesh with said second gear; and

a third lever connected to said second gear, said second cam follower means being connected to said third lever.

7. Apparatus as defined in claim 2 and comprising means for extracting the bottommost blank from the stack.

8. Apparatus as defined in claim 7 wherein said means to extract the bottommost blank from the stack comprises: a rotatable roller which is engageable with the bottommost blank; and drive means to rotate the roller.

Claims

1. Apparatus for supporting a stack of blanks of sheet material one on top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising: means for supporting the stack of blanks one on top of another; a first lever device including a suction nozzle and operable to engage the nozzle with the bottommost blank in the staCk and bend down one edge of said bottommost blank; a second lever device operatively connected to a plunger and operable to insert the plunger between the bent down edge of said bottommost blank and blanks above the bottommost blank; a third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack; a rotatable single track cam device; first, second and third cam-follower means engageable with the single track of said cam device and operatively connected to said first, second and third lever devices respectively; and drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device.

2. Apparatus for supporting a stack of blanks of sheet material one on top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising: means for supporting the stack of blanks one on top of another; a first lever device including a suction nozzle and operable to engage the nozzle with the bottommost blank in the stack and bend down one edge of said bottommost blank; a second lever device operatively connected to a plunger and operable to insert the plunger between the bent down edge of said bottommost blank and blanks above the bottommost blank; a third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack; a rotatable cam device; first, second and third cam-follower means engageable with said cam device and operatively connected to said first, second and third lever devices respectively; and drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device, said rotatable cam device comprising a disc which is rotatable about an axis and is formed with an elliptical groove in one face of the disc, said groove being eccentric to said axis and said first, second and third cam follower means all engaging in said groove.

4. Apparatus for supporting a stack of blanks of sheet material one one top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising: means for supporting the stack of blanks one on top of another; a first lever device including a suction nozzle and operable to engage the nozzle with the bottommost blank in the stack and bend down one edge of said bottommost blank; a second lever device operatively connected to a plunger and operable to insert the plunger between the bent down edge of said bottommost blank and blanks above the bottommost blank; a third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack; a rotatable cam device; first, second and third cam-follower means engageable with said cam device and operatively connected to said first, second and third lever devices respectively; drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device; and a closed housing and bearing means within said housing carrying said first, second and third lever devices and cam follower means within said housing.

5. Apparatus for supporting a stack of blanks of sheet material one on top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising: means for supporting the stack of blanks one on top of another; a first lever device including a suction nozzle and operable to engage the nozzle with the bottommost blank in the stack and bend down one edge of saId bottommost blank; a second lever device operatively connected to a plunger and operable to insert the plunger between the bent down edge of said bottommost blank and blanks above the bottommost blank; a third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack; a rotatable cam device; first, second and third cam-follower means engageable with said cam device and operatively connected to said first, second and third lever devices respectively; and drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device, at least one of said lever devices comprising a lever pivotally mounted on a pivot and connected firstly to a roller forming the respective cam follower means and secondly to a toothed sector which is in engagement with a gear.

6. Apparatus for supporting a stack of blanks of sheet material one on top of another and for separating a bottommost blank in the stack from other blanks in the stack, comprising: means for supporting the stack of blanks one on top of another; a first lever device including a suction nozzle and operable to engage the nozzle with the bottommost blank in the stack and bend down one edge of said bottommost blank; a second lever device operatively connected to a plunger and operable to insert the plunger between the bent down edge of said bottommost blank and blanks above the bottommost blank; a third lever device operatively connected to a device for lifting blanks which are above the bottommost blank in the stack; a rotatable cam device; first, second and third cam-follower means engageable with said cam device and operatively connected to said first, second and third lever devices respectively; drive means adapted to rotate said cam device in a direction so as to produce sequential operation of said first lever device, said second lever device and said third lever device; guide means guiding said plunger for longitudinal displacement of said plunger; a toothed rack member connected to said plunger, and a first gear in mesh with said toothed rack member, said second lever device comprising a first lever connected to said first gear; a link member pivotally connected to said first lever; a second lever pivotally connected to said link member; a second gear connected to said second lever; a toothed sector in mesh with said second gear; and a third lever connected to said second gear, said second cam follower means being connected to said third lever.