US3755041A

US3755041A - Bag making machine with adjustable gears

Info

Publication number: US3755041A
Application number: US00206475A
Authority: US
Inventors: H Membrino
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-11-06
Filing date: 1971-12-09
Publication date: 1973-08-28
Anticipated expiration: 1990-08-28

Abstract

A machine for making bags from strips of thermoplastic material whereby the strip, either longitudinally overfolded or tubular, is passed from a supply roll over an impression roller where it is momentarily contacted by a heated blade means, which severs and seals along a line of seal to form the bags. The heated blade means is preferably in the form of an integral unit having two oppositely-extending blade portions. The blade means is rotated to bring the blade portions into alternate contact with the strip so that one complete rotation of the blade means forms two bags. The blade means is mounted on a shaft which is actuated by an elliptical gear assembly so that there is a variation in the speed of rotation of the blade means, Between the elliptical gear assembly and the shaft on which the blade means is mounted is a simple manual worm assembly to vary the rotational speed of the blade means as desired, and, thereby, various sizes of bags can be produced.

Description

United States Patent 1 Membrino BAG MAKING MACHINE WITH ADJUSTABLE GEARS [76] Inventor: Hercules Membrino, 1934 Arch St.,

Philadelphia, Pa. 19103 [22] Filed: Dec. 9, 1971 [211 App]. No.: 206,475

Related US. Application Data [63] Continuation-impart of Ser. No. 136,862, April 23, 1971, which is a continuation-in-part of Ser. No.

874,523, Nov. 6, 1969, Pat. No. 3,616,095.

52 us. Cl. .l 156/515, 156/582 [51] Int. Cl B32b 31/00 [58] Field of Search 156/515, 582.3, 251, 156/359 [56] References Cited UNITED STATES PATENTS 3,053,723 9/1962 Plach et a1. 156/515 3,083,757 4/1963 Kraft et a1 156/515 3,360,416 12/1967 Cochrane.. 156/359 3,492,190 l/1970 Poncy... 156/583 3,522,135 7/1970 Page 156/251 Y [111 3,755,041 [45'] Aug. 28, 1973 Primary Examiner-Douglas J. Drummond Attorney-Arthur A. Jacobs et a1.

[5 7] ABSTRACT A machine for making bags from strips of thermoplas-- tic material whereby the strip, either longitudinally overfolded or tubular, is passed from a supply roll over an impression roller where it is momentarily contacted by a heated blade means, which severs and seals along a line of seal to form the bags. The heated blade means is preferably in the form of an integral unit having two oppositely-extending blade portions. The blade means is rotated to bring the blade portions into alternate contact with the strip so that one complete rotation of the blade means forms two bags. The blade means is mounted on a shaft which is actuated by anlelliptical gear assembly so that there is a variation in the speed of rotation of the blade means, Between the elliptical gear assembly and the shaft on which the blade means is mounted is a simple manual worm assembly to vary the rotational speed of the blade means as desired, and, thereby, various sizes of bags can be produced.

7 Claims, 7 Drawing Figures Patented Aug. 28, 1973 3 Sheets-Shet 1 [llliilll llllllllllllll Patented Aug; 28,1973

3 Sheets-Sheet 2 Patented Aug. 28, 1973 3,755,041

3 Sheets-Sheet 5 -1 BAG MAKING MACHINE WITH ADJUSTABLE GEARS This is a continuation-in-part of co-pending U.S. Pat. application Ser. No. 136,862, filed Apr. 23, 1971, which is, in turn, a continuation-in-part of U.S. Pat. application Ser. No. 874,523, filed Nov. 6, 1969, and issued as Pat. No. 3,616,095 on Oct. 26, 1971.

This invention relates to a machine for making bags from thermoplastic material, and it particularly relates to a machine of this type which is capable of making bags of various sizes.

Machines of this type generally comprise a supply roll of thermoplastic strip material of double-ply construction, that is, either longitudinally overfolded sheet material or tubular material, from which the strip is passed over an impression roller. As it passes over the impression roller, a heated knife, wire or the like, is passed into momentary contact with the strip to simultaneously form a line of seal and to sever the strip along the line of seal, thereby forming a series of bags. The heated knife or wire was, generally, mounted on a rotatable cylindrical head which rotated in synchronism with the impression roller so that a predetermined length of strip would pass around the impression roller between each contact by the heated knife or wire, thereby forming bags of predetermined size.

One disadvantage of these prior machinesv was the fact that they could only make one size of bags unless the machine was stopped and taken out of service, so that different parts, such as the sealing head, gears, 'etc., could be substituted for the original parts.

Another disadvantage of these prior machines was that they were generally provided with means, such as masking strips covering small portions of the knife or wire, or recesses in the knife or wire, or similar means, which prevented passage of sufficient heat to sever the strip of those areas. This formed so-called nips or connections between the otherwise separated bags. One reason for the formation of these nips" was to enable the bags to remain in a strip for packaging, filling or other purposes. However, even when it was not desirable to retain the bags in a strip, it was still necessary to do so because the thermoplastic bags have a tendency to stick to the heated knife or wire, but by retaining the bags in a strip and by maintaining a constant tension on the strip during its forward movement, the bags were pulled away from the heating means and this sticking tendency was overcome. However, this requirement for forming connecting nips required the provision of extra mechanical parts and. labor which could be eliminated if the necessity of having nips could be eliminated. I

One object of the present invention is to overcome the above and other disadvantages of prior machines of this type by providing a bag making machine which can be easily adjusted, with little interruption in its operation, to make different sized bags.

Another object of the present invention is to provide a continuous motionbag making machine of the aforesaid type which eliminates the necessity of forming connecting nips" between the bags in order to prevent sticking to the heated sealing and severing means.

Other objects and many of the attendant advantages of this invention will be readilyappreciated as the same becomes better understood by reference to the following description when read in conjunction with the accompanying drawings wherein:

FIG. 6 is a perspective. view of the elliptical gears.

FIG. 7 is an enlarged, detailed, perspective view of the sealing head.

Referring now in greater detail to the drawings wherein similar reference characters refer to similar parts, there is shown a machine, generally designated 10, comprising'a pair of oppositely-disposed walls or side plates 12 'and 14 between which extends a drive shaft 16 operated by an electric motor 18 through an endless drive chain 20 movable around sprocket 22 on the motor shaft and sprocket 24 on the drive shaft 16. Also mounted on the drive shaft 16, adjacent the external surface of plate 12, is a change gear 26. The change gear 26 is removably connected to the shaft 16 so that it may be easily replaced by other similar change gears of different sizes in accordance with the desired speed of the impression'roller which, in turn, affects the size of the bags. v

The change gear 26 is in mesh with an intermediate idler gear 28 which is mounted for rotation on a stub shaft 30 which is supported by a rocker arm 32. The rocker arm 32 is connected at its upper end to a rotatable shaft 34 which'supports the impression roller 36. The mounting of the gear 28 on the rocker arm 32 is to permit the gear 28 to be adjusted relative to the change of gear 26 so that it is always maintained in mesh therewith regardless of the size of the change gear. Any'desired standard means may be used to retain the rocker arm in adjusted position. One such means may take the form of a lock screw and slot connection (not shown) between the rocker arm 32 and the wall 12, such as shown, for example, in U.S. Pat. No. 3,233,527.

The idler gear 28 is also in mesh with a gear 38 mounted on the shaft 34, the gear 38 acting to rotate the shaft 34. The rotation of the shaft 34 may be varied somewhat, however, by means of a differential gear mechanism which includes the worm gear 40 mounted on the shaft 34 coaxially with the gear 38. The worm gear 40 and a plurality of pinion gears 42 are all mounted on a disc which rides freely on shaft 34. These pinion gears 42 are in mesh with a beveled gear 44 on one side of the gear 40 and a beveled gear 46 on the opposite side of gear 40. The gear is connected to gear 38 by asleeve 48 which rides freely on the shaft 34, while the gear 46 is pinned to the shaft 34, as indicated at 50. When the gear 40 is rotated to move the pinion gears 42 in the same direction as the rotation of the shaft 34, this causes the gear 46 to rotate in the oppositedirection, thereby slowing down the rotation of the shaft 34 and, consequently, of the impression roller 36. If the gear 40 is rotated in the opposite direction, the speed of rotation of shaft 34 is increased. This differential gear assembly is a standard type mechanism which is generally disclosed, for example, in U.S. Pat. No. 3,233,527.

The gear 40 is actuated by a worm 52 mounted on a shaft 54 operatively connected to an electrical motor 56. The motor 56 is actuated by an electric eye assembly, indicated at 58 in FIG. 1. This electric eye mechanism is also of a standard type and its structure and operative connection to the motor 56 may be of any desired arrangement. An example of such arrangement is disclosed in greater detail in the aforementioned U.S.

Pat. No. 3,233,527. A manually operable disc 60 is connected to the upper end of the shaft 54. This disc can be rotated by hand to obtain faster adjustment or greater adjustment than is obtainable by means of the electric eye mechanism.

The electric eye mechanism may be used in conjunction with spots or other printed matter on the strip, and is used to compensate for variation of the printed matter due to shrinking or stretching of the strip material. In this respect, the strip material may be imprinted with advertising or other indicia which is so placed that the design is repeated for each area which is to correspond to an individual bag. Since the material is stretchable, the indicia may move out of register with the heated sealing means so that the lines of seal would cut through the printing. The electric eye mechanism detects such variations in that when it detects the printing in the wrong place, it closes a switch and activates the motor 56 which, in turn, activates the differential gear mechanism described above, moving the impression roller faster or slower as called for by the electric eye.

The plastic strip material 62, either overfolded sheet stock or tubular stock, (both types being generically referred to as double-ply material), is supplied from a 'roll thereof designated 63 mounted on a removable spool 64. The strip is initially threaded under a draw roller 65, which is driven in synchronism with the shaft 34 by

gears

66 and 67, or by any other desirable means,

over the impression roller 36, and under a sealing head 68.- It is also optionally held against the impression roller 36 by an idlerpresser roller 70. As the impression roller and draw roller thereafter rotate, the strip 62 is drawn from thesupply roll 63.

The impression roller 36 is provided with a series of laterally spaced grooves 72 (see FIG. 4) within which are arranged endless belts or tapes 74. These tapes 74 also extend around roller 76 on a shaft 78 and are used primarily to prevent sticking and wrapping around of the plastic strip on the impression roller 36. Although relatively wide tapes are illustrated, narrow tapes or chains may be subtituted if desired. Also mounted on shaft 78 are rollers which support endless belts 80 in conjunction with similar rollers mounted on a shaft 82. The belts coact with similar belts 84 extending between rollers on

shafts

85 and 86, the two endless belts acting as conveying means for the completed bags. The conveyor belts are driven by an endless chain 87 extending between a sprocket 88 on shaft 34 and a sprocket 89 on the tending between a sprocket 88 on shaft 34 and a sprocket 89 on the shaft 85.

The sealing head 68 is best illustrated in FIG. 4 and 7 and comprises a pair of oppositely disposed blades 90 constructed of metalor other heat conducting substance. The blades, including the heating elements lating strip 96 by any desirable means such as bolts, clamps, adhesive, etc., these strips 96 being provided in order to reduce heat transfer to the shaft 94. Heat is supplied to the blades by electrical heating elements 98 positioned in corresponding bores in the respective blades 90. These heating elements are in electrical circuit with a source of electrical energy through any desired standard means such as flexible cables, commutators, or the like. 7

The provision of two opposed blades pennits the formation of two bags during each complete rotation of the sealing head.

Another feature inherent in this construction is that there is such a rapid movement of the blades immediately after contact between the blades and the strip that the blades break away from the strip before it can stick to them. Futhermore, the rapid movement of the blades actually acts to kick the severed bags away from the strip and onto the conveyor. In this manner, the necessity for having nips to permit the formed bags to be pulled away from the sealing head is obviated.

The shaft 94 is rotatably mounted between a pair of bearing blocks 100 which are vertically slidable in corresponding guideways 102 on the

respective wall

12 and 14. The blocks 100 are adjustable toward and away from the impression roller 36 by means of screws 104 (see FIGS. 1 and 2) which extend through corresponding blocks 106. Each screw is held in adjusted position by a nut 108.

Mounted on the shaft 94 is a sprocket which is driven by an endless chain'll2 from a sprocket I14 freely rotatable on the shaft 34. The chain 112 is held in tension by a spring-pressed idler sprocket 116 which permits adjustment of the chain as the shaft 94 is vertically adjusted.

An oval or double lobe elliptical gear 1 18 is mounted on the drive shaft 16 (note FIGS. 3 and 5). The gear 1 18 is in mesh with a second oval or elliptical gear 120. The gear l20 is mounted on a bushing 122 which is freely slidable and rotatable on the shaft 34. The gear is connected, as by means of screws 124 or the like, to a bevel gear 126 which is also mounted on the bushing 122. Adjacent the bevel gear 126, mounted on a freely rotatable bushing 128, is a worm gear 130. Connected to the gear 130 are a plurality of pinion gears 132. These pinion gears 132 are in mesh with both the bevel gear 126 and a second bevel gear 134 on the opposite side of the worm gear 130 and in opposed relation to the bevel gear 126. The bevel gear 134 is also mounted on and independently rotatable bushing 136 and is connected, as by screws 138 or the like, to the sprocket 114, which is, itself, mounted on the bushing 136. A worm 142 is in mesh with the worm gear 130, this worm 142 being mounted on a shaft 144 which is rotatable by a manually-operable disc handle 146.

The elliptical nature of the gears 1 l8 and 120 permits a variation in the speed of rotation whereby the two end portions, or end lobes, of the gears effect a more rapid movement than the side portions between the lobes. Therefore, the end lobes of the gears cause a relatively rapid movement of the corresponding blades of the sealing head into and out of contact with the thermoplastic strip, while the sides of the gears cause a relatively slower movement of the blades.

A previously indicated, the rotational or surface speed of the impression roller 36 may be varied by varying the size of the change gear 26. Heretofore,

. 5' when this was done, it was also necessary to change the sealing head assembly to make it larger or smaller to correspond to the variation'in speed of the impression roller. By means of the present invention, the necessity for this replacement of the sealing head assembly is eliminated.

When the high lobesof gear 118 meet the low lobes of gear 120, shaft 94 is rotating at a fast speed, when the low lobes of gear 118 meet the high lobes of gear 120, shaft 94 rotates at a slower speed. Therefore, with the use of elliptical gears, shaft 94 is rotated at various speeds between the high and low lobes of gear 1 18 with each revolution of drive shaft 16.

Drive shaft 16 also drives the impression roller 36 through change gear 26. As different change gears are used, the impression roller 36 rotates at different surface speeds.

By setting the position of the sealing blades to the corresponding position of the gear ratio on the

elliptical gears

118 and 120 equal to the change gear, the surface speed of both the impression roller 36 and the sealing blades 98 are in harmony.

The selection of the correct position of the sealing blades corresponding to the gear ratio on the elliptical gears is accomplished by the differential mechanism which is positioned between them. By rotating worm 142, which moves gear 130 and pinion gears 132, bevel gear 134 and sprocket 114 will speed up or slow down, changing the position of the sealing blades 98 relative to the position of the end lobes of the

elliptical gears

118 and 120. The selection of the proper gear ratio of the elliptical gears 1 l8 and 120 that is required in order to have the surface speed of the sealing blades 98 match the surface speed of the impression roller 36, may be made by trial and error method. Thisrequires the stopping of the machine, disengaging sprocket 110 from shaft 94, turning shaft 94 forward or backward as an estimated adjustment, engaging sprocket 110 to shaft 94, and running the machine to test. This method could require several adjustments.

However, with the use of the differential mechanism, not stopping or down time is needed when change gear 26 is replaced with a different size gear to make a differnt size bag. The correct and accurate ratio selection is made at once by turning worm 142 while the machine is in motion. q

Although the elliptical gear differential assembly and the sprocket 114 are here illustrated as being mounted for independent rotation on the sahft 34, it is to be understood that this is merely for convenience and simplicity because the shaft 34 acts merely as a supporting means. If desired, these elements maybe mounted on I a separate stub shaft connected to a side plate of the machine in an ofiset relationship relative to the shaft 34.

It is to be noted that although the sealing head 68 is illustrated as an integral unit with oppositely-disposed blade portions, and although this illustrated form is the preferred form, it is also possible to use other typesof sealing heads, as, for example, a cylinder with spaced knife blades, ribbons, wires, or the like on tis periphery, the term strips" being used to generically describe such ribbons, wires or the like. It is also possible to utilize the form of the device shown in FIG. 5 but to make the ends somewhat flatter and to stretch wires therealong, these wires acting as the sealing and severing means.

The invention claimed is:

l. A bag making machine comprising a supply means for supplying a strip of double-ply thermoplastic material, a rotatable impression roller, a first drive means operatively connected to said impression roller to rotate said impression roller, a first speed varying means operatively connected to said first drive means for varying the speed of rotation of said impression roller, a rotatable heated sealing and severing means, a second drive means operatively connected to said sealing and severing means to rotate said sealing and severing means,,and a second speed varying means operatively connected to said second drive means for varying the speed of rotation of said sealing and severing means in correlation with the speed of surface rotation of said impression roller, said various means being operatively connected to each other and being constructed and arranged to pass said strip from said supply means over said impression roller, said impression roller supporting said strip while said sealing and severing means, during rotation thereof, impacts said strip to form lines of seal and severance which are spaced from each other by a predetermined distance longitudinally of said strip.

2. The machine of claim lwherein said second drive means comprises a drive shaft having a first elliptical gear mounted thereon, a second elliptical gear in mesh with said first elliptical gear, said second elliptical gear being operatively connected to an actuating means which is operatively connected to said sealing and severing means for rotating said sealing and severing means, and a differential gear assembly operatively connected between said second elliptical gear and said actuating means, said differential gear assembly comprising said second speed varying means.

3. The machine of claim 2 wherein said differential gear assembly comprises a worm gear having at least one pinion gear connected thereto, said pinion gear being in mesh with oppositely-disposed bevel gears, one on each side of the worm gear, one of said bevel gears being connected to said second elliptical gear and the other bevel gear being connected to said actuating means, and adjusting means for adjusting both said differential gear assembly and the radial positions of said elliptical gears.

4. The machine of claim 3 wherein said adjusting means is a worm in meshwith said worm gear, said worm being mounted on a worm shaft, and a manuallyoperable handle operatively connected to said worm shaft.

5. The machine of claim 1 wherein said sealing and severing ,means comprises at least two oppositelydisposed heated severing elements.

6. The machine of claim 5 wherein said sealing and severing elements are heated blades extending radially from a rotatable hub portion.

7. The machine of claim 5 wherein said sealing and severing elements are heated strips.

* i i i

Claims

1. A bag making machine comprising a supply means for supplying a strip of double-ply thermoplastic material, a rotatable impression roller, a first drive means operatively connected to said impression roller to rotate said impression roller, a first speed varying means operatively connected to said first drive means for varying the speed of rotation of said impression roller, a rotatable heated sealing and severing means, a second drive means operatively connected to said sealing and severing means to rotate said sealing and severing means, and a second speed varying means operatively connected to said second drive means for varying the speed of rotation of said sealing and severing means in correlation with the speed of surface rotation of said impression roller, said various means being operatively connected to each other and being constructed and arranged to pass said strip from said supply means over said impression roller, said impression roller supporting said strip while said sealing and severing means, during rotation thereof, impacts said strip to form lines of seal aNd severance which are spaced from each other by a predetermined distance longitudinally of said strip.

2. The machine of claim 1 wherein said second drive means comprises a drive shaft having a first elliptical gear mounted thereon, a second elliptical gear in mesh with said first elliptical gear, said second elliptical gear being operatively connected to an actuating means which is operatively connected to said sealing and severing means for rotating said sealing and severing means, and a differential gear assembly operatively connected between said second elliptical gear and said actuating means, said differential gear assembly comprising said second speed varying means.

4. The machine of claim 3 wherein said adjusting means is a worm in mesh with said worm gear, said worm being mounted on a worm shaft, and a manually-operable handle operatively connected to said worm shaft.

5. The machine of claim 1 wherein said sealing and severing means comprises at least two oppositely-disposed heated severing elements.