WRAPPING MACHINE

Abstract: This invention relates to a wrapping machine, preferably for wrapping an object (2) with a plastic film (1). The object of the invention is to increase the flexibility and shorten the set-up time of a machine of this kind. This has been achieved by arranging the film feeder (3) and the ''cut-off sheet''-feeder (5) respectively with variators (12 resp. 11). By means of these variators it is possible to adjust the number of revolutions of the film feeder (3) and the ''cut-off sheet''-feeder (5) respectively in a continous manner, independently of each other. Accordingly, it is possible by means of one of the variators (12) to adjust the sheet length in a precise manner and, by means of the other variator (11), to center said cut-off sheet.

Description: Title: Wrapping machine Technical field: This invention relates to a wrapping machine, in accor¬ dance with the precharacteriing portion of claim 1, i.e. a wrapping machine, for wrapping of an object by means of a sheet-like material, preferably a plastic film, which is stored continously, sheet-like adjacent the machine before the wrapping process, whereby said material and object are fed to a first wrapping point with a differen¬ ce of direction which preferably amounts to about 90°, comprising an object feeder, for feeding of said object to a point shortly in front of said wrapping point and past it; a feeding means for feeding of said sheet-like materi _.! ; a cutting device for cutting of said sheet-like materi _.l and a "cut-shee "-feeder which in an intermit- tent m inner feeds said cut-off sheet. Background and technical problem: Known /rapping machines of the above kind, see for exam¬ ple US-A-2 62 * 5 779, present several disadvantages. Most of all, the set-up time for machines of this known kind, specially concerning the adjustment of size, are too long. It is a common strive within the highly developed production of today to diminish the set-up times. Up to this point, it has not been possible to diminish said set up time without having inacceptably high costs. Solution and advantages: The object of the present invention is to achieve a wrap¬ ping machine which provides high flexibility and short set up times. Further, such a machine should provide high reliability and preferably also be purchasable to a rela¬ tively low price. The above object is achieved by means of a machine in accordance with the invention, which is characterized in that said means for feeding the continuos sheet comprises a controlling device which enables continous adjustment of the feeding velocity, in relation to the cutting devi¬ ce, and that said "cut-off sheet"- feeder comprises a controlling device which enables continous adjustment of this latter feeding velocity, in relation to the cutting device, wherein said adjustments can be made independent¬ ly of each other. Brief description of drawings: The invention will be described in more detail in the following, by way of example, with reference to the at¬ tached drawings, in which; Fig. 1 shows a perspective view of a machine of which certain parts present a preferred embodiment of the invention and. Fig. 2 shows a perspective view of essential parts of a preferred embodiment of the invention. Hence, in Figure 1 there is shown a wrapping machine. This machine comprises amongst other things, a continous sheet of a plastic film 1. The plastic film 1 is fed by means of a feeding unit 3, comprising two counter rota¬ ting rollers 32, 33. In the extension of the direction of transportation of the film 1, there is firstly located a cutting device 4, which cuts the continous sheet of film into sheets having a desired length. Further, in said direction of transportation there is a "cut-off sheet"- feeding device 5, which should feed the cut-off sheet to a desired wrapping position 17. The object 2, which is to be wrapped, is fed to this wrapping position 17 by means of feeding devices 18, 19, which are not described in de¬ tail. Moreover, it is shown that the direction of move¬ ment of the plastic film 1 and the direction of movement of the object 2 which is to be wrapped 17 are substanti- ally perpendicular. This implies that the object 2 which is to be wrapped meets the plastic film 1 in a direction which is transversially oriented in relation to the main plane of the plastic film. The object which is to be wrapped 2 is fed in a cam con¬ trolled manner through the plastic film 1. The plastic film 1 is continously fed by the machine. A prerequisite for obtaining desired wrapping of the object 2, is that the object 2 hits the cut sheet of plastic film on a cer- tain spot, i.e. on a certain distance from the upper and the lower edge respectively of said film. This is a pre- requis^e in order to make it possible for the after-co¬ ming wrapping arrangement (not shown in detail) to com¬ plete wrapping of the object in a desired manner. Accor- ding to the invention, the hit at the wrapping spot 17, between the object 2 and the sheet 1, is controlled by adjusting the velocity of the "cut-off sheet"-feeding device 5. Figure 2 shows in a more detailed manner the essential parts of a preferred example of a machine according to the invention. In this case, frequency controlled engine 6 powers a fan belt transmission 20, of which one part 16 is arranged on a shaft 7 which actuates the cutting devi- ce 4. The cutting device 4 consists of a cylindrical longish element provided with a rotating cutting edge 41 and an interacting stationary cutting edge 42. A feeding device 3 is arranged above the cutting device 4, which feeding device 3 comprises two counter rotating rollers 32, 33. These two counter resisting rollers are driven synchronically by means of a transmission 34. The input shaft 31 of said transmission 34, does not only provide an extension of one of said two shafts, but does also provide the output shaft of a controlling device 12. This controlling device is a mechanical transmission and has an input shaft 22 which is driven via a transmission 8, 10, wherein one of the transmission parts 8 is fixed to the shaft 7 of the cuttting device 4. The controlling device 12 presents a manually actuatable element 23 by means of which the ratio, via the controlling device 12, is continously adjustable. Accordingly, it is possible by means of adjustment of the manoeuvre device 23, to adjust the number of revolutions n2, for the output shaft 31, despite having constant input number of revolutions nl for the input shaft 22 (n2=X*nl; wherein X defines the ratio). The "cut-off sheet"-feeding device 5 is arranged under¬ neath the cutting device 4, on the opposite side in rela¬ tion to the feeding device 3. The "cut-off sheet"-feeding device 5 comprises a number of endless belts 13, 14. These belts 13, 14 have their main extension in the fee¬ ding direction of the film 1. Each such conveyor compri¬ ses two parallelly arranged driving units. Each driving unit has a longish belt 13 and 14 respectively, arranged on each side of the feeding plane of the film 1. The belts 13, 14 are driven in such a manner that the belt parts closest to each other move in the same direction, i.e. those parts closest to the film 1. The distance bet¬ ween these most closely located parts must be such that a gap 15 is created there between, even when the plastic film is located therein. Accordingly, the gap 15, between the two driving parts of the belt, has to be so large that these can "spin" on the film, if the film is retai¬ ned by a sufficient force. This is a condition for the functioning of the machine, which will be made clearer below. Each belt 13, 14 is driven by a pulley 53, 53', 54, 54' and runs about opposite non-driving pulleys. The driving pulleys are arranged in pairs 54, 54' and 53, 53' respectively, on a respective shaft 51 and 52. These shafts are driven simultaneously by means of a trans- mission device 55. The input shaft 51 of this latter transmission device provides the extension of one of the said shafts and does also provide the output shaft of a second controlling device 11. This controlling device, as the first one, provides a mechanical transmission, a so called variator. The function thereof is accordingly, exactly as has been described above. This second control¬ ling device 11 is also driven via an input shaft 21 which via a wheel-like transmission 9, 8 interacts with the shaft 7 in the middle. In the fcllowing it will be described how it is possible in a flexible manner to adjust/control the feeding of the cut-off sheet and the lenght thereof, independently of the object: 2 which is to be wrapped, thanks to a device according to the invention. A prerequisite is that the machine in its steady state feeds the objects 2 which are to be wrapped, in a cam steered manner and that the cut¬ ting shaft 7 is synchronised with the feeding velocity of the object, i.e. the rotational speed of the cam shaft. The plastic film 1 is fed to, and passes, the cutting device, into the gap which is created between the statio¬ nary cutting edge 42 and the rotating edge 41 in its non- cutting position, and is further fed down to the "cut-off sheef'-feeder 5. At each longitudinal edge of the plastic sheet, or at least adjacent to these, there is a driving belt 13, 14 which is located in the longitudinal direc¬ tion of the sheet, on each side of the film. Thanks to the gap existing between the two closest parts of the driving belt 13, 14, the film is fed with a speed which is determined by the continous film feeder 3, even if the feeding velocity of the "cut-off sheef'-feeder 5, is hig- her than the feeding speed of the continous film feeder 3. The belts 13, 14, accordingly slip on the plastic film. Therefore, when the cutting device 4 completes a revolution, the plastic film will be cut off, a sheet lenght being determined by the feeding velocity of the continous film feeder 3. This cut-off sheet is from this moment fed by the "cut-off sheef'-feeder 5 and, accor¬ dingly, fed downwards with a velocity which is determined by the "cut-off sheef'-feeder 5. At a certain moment this downward moving cut-off sheet will come in contact with the object 2 which is to be wrapped. The object 2 will then hit the film at a certain location 17, having a di¬ rection of movement which is mutual with the normal of the plane in which the cut-off plastic film is located. If it is desired to increase the lenght of this sheet, for example to provide a sheet for a larger object 2, it is merely necessary, by means of the manoeuvre device 23, to adjust the ratio in one of the variators 12 so that the velocity of the feeding rollers 32, 33 of the conti¬ nous film feeder 3 obtains that higher speed which corre¬ sponds to the desired sheet length. The sheet length (1) is related to the product of the time (t), for performing a revolution of the cutting shaft 41 and the peripheral velocity (v) of one of the driving rollers 32, 33 (l=t*v). In order to then position the cut-off sheet on the desi¬ red location 17 at the moment of impact with the object 2, it is only necessary to, by means of the ma¬ noeuvre device 24 of the second variator, adjust the ve¬ locity of the "cut-off sheef'-feeder 5 so that the sheet has been fed a certain desired distance at the moment of impact with said object 2. In the preferred embodiement a frequency controlled engi¬ ne 6 is used, which has a rev. interval between 79-171 r/min. By means of the chosen belt transmission 20 this provides the shaft 7, for the cutting device 4, with a rev. interval of 60-150 r/min. By means of the used var¬ iators it is accordingly possible to vary this rev. ratio of the shaft via these, 11 resp. 12, so that the rev. ratios of the output shaft 31 and 51 respectively is kept within the interval 403-1079 r/min. It is obvious for the skilled man that the above descri¬ bed is by way of example only and does not limit the sco¬ pe of the invention, but is only limited by the following claims. For instance, it is evident for the skilled man that all kind of transmissions can be used, i.e. not only belt transmissions and gear wheel transmissions as shown. Moreover, it is evident that the machine is also suited for use together with other kinds of sheet-like material, such as paper or aluminium foil. The variators 11, 12 do not exclusively have to be of a mechanical type. It is for instance also possible to let frequency controlled engines drive the rollers 3 and the "cut-off sheef'-feeder 5 respectively, which by means of controlling means can be given the correct respective velocities in respect to the cutting device 4. Further, it is possible to use several kinds of cutting devices 4, such as two counter rotating edges and also one (or two) in the same plan reciprocially movable ed- ge/es. It is not a necessity that the object to be wrapped has a direction of movement which is parallel to the normal of the plastic film. In fact, this direction of movement can diverge from said normal up to 45°.

Claims: Claims 1. Wrapping machine, for wrapping of an object (2) by means of a sheet-like material (1), preferably a plas¬ tic film, which is stored continously and sheet-like sto¬ red adjacent the machine, whereby said material (1) and object (2) are fed to a first wrapping point (17) with a difference of direction which preferably amounts to about 90°, comprising an object feeder (18, 19), for feeding of said object (2) to a point shortly in front of said point (17) and past it; feeding means (3) for feeding of said sheet-like material (1); cutting device (4) for cutting of said sheet (1); a "cut-sheef'-feeder (5) which in an intermittent manner feeds said cut-off sheet (1); c h a r a c t e r i z e d in that said means (3) for feeding comprises a controlling device (12) which provid¬ es continous adjustment of the feeding velocity, in rela- tion to the cutting device (4), that said cut-off sheet feeder (5) comprises a controlling device (11) which pro¬ vides for continous adjustment of this feeding velocity, in relation to the cutting device (4), whereby said ad¬ justments can be made independently of each other. 2. Wrapping machine according to claim 1, c h a¬ r a c t e r i z e d in that said means (3) , cutting de¬ vice (4) and "cut-off sheef'-feeder (5) are indirectly driven by one and the same power source (6) , which prefe- rably is a continously controlable engine. 3. Wrapping machine according to claim 2, c h a¬ r a c t e r i z e d in that said cutting device (4) is driven by a shaft (7) which via a transmission (20) is driven by said power source (6) and that the input shaft (21 resp. 22) of the controlling device (11 resp. 12) is driven by means of a transmission (8,9,10) which input shaft (8) is arranged on said shaft (7). 4. Wrapping machine according to claim 3, c h a- r a c t e r i z e d in that said controlling devices (11 resp. 12) are mechanical units, which present manoeuvre devices (23 resp. 24), which when actuated affect an in¬ ner transmission mechanism so that the number of revolu¬ tions of the output shaft (31 resp. 51) of the control- ling device (11 resp. 12) can be varied. 5. Wrapping machine according to claim 1, c h a¬ r a c t e r i z e d in that said means (3) for feeding comprises two counter rotating rollers (32,33). 6. Wrapping machine according to claim 1, c h a¬ r a c t e r i z e d in that said cutting device (4) com¬ prises a longish excentrically arranged rotating edge (41) and a longish stationary edge (42) which interacts therewith. 7. Wrapping machine according to claim 1, c h a¬ r a c t e r i z e d in that said "cut-off sheef'-feeder (5) comprises two parallelly arranged drive mechanisms, each comprising two endless belts (13,14) which both ex¬ tend in the direction of the feeding and which are driven by two parallelly arranged counter rotating shafts (51, 52) in such a manner that there is a smaller gap (15) between the two most closely positioned parts of the belts (13, 14) which are also rotating in the same direc¬ tion.

Inventors: ANDERSSON BIRGER, ANDERSSON, BIRGER
Applicants: ARENCO MATCH MACHINERY AB
Application year: 1990
Main classification: B65B59
IPC codes: B65B41