FIELD OF THE INVENTION

The present invention relates to a high-speed vertical form-fill-seal packaging machine for forming a film into packaging bags, filing with product and sealing the packaging bags in sequence. More particularly invention relates to avertical form-fill-seal machine with an improved sealing assembly to achieve high speed operation.

BACKGROUND ART

Generally, a vertical form-fill-seal packaging machine which forms a film or laminate in roll into packaging bags filled online with product and sealed in sequence. The film unwind from a roll is formed into a tube with the side edges thereof held overlapped while the film is transferred downwards along a vertical transfer route. The overlapped side edges of the tubular film are bonded (lap, fin or pinch sealed for example). The lower end of the tubular film is sealed transversely. The products are supplied into the tubular film in measured quantity and then the upper end of the tubular film is transversely sealed to separate the sealed tubular film from the tube above so that packaging bags, each having the product sealed therein, are produced in sequence. Bags are either separated by transverse sealing jaws or perforated between the two consecutive bags.

In the above case, the sealing of the tubular film in the verticaldirection i.e. travelling direction downwards is generally performed by heating and pressure-bonding the overlapping edges of the tubular film by bringing a pair of devices called sealing jaws arranged parallel to the film transfer route, into contact with each other. In this case, however, the method of bringing the sealing jaws into contact with each other by reciprocating the jaws in directions in which they come in contact with, and separate from each other, has the disadvantage that since the sealing of the film can be made only at the point of contact between the pair of sealing jaws, the transfer of the film has to be stopped for a minimum period required for sealing (dwell time). To avoid such a limitation in case of transverse sealing, there has conventionally been known a method in which the sealing jaws are configured to move with the tubular film after they come into contact, and move away from, each other and return back in the opposite direction of the film transfer route. They thereby follow the tubular film speedwhile pressing the tubular film for sealing as the film is continuously transferred. However, for sealing the moving film in vertical direction the mechanisms available are inefficient to seal the film in moving direction i.e. parallel to the axis of moving tube. Therefore, there is a need for sealing mechanism in vertical Form Fill and Seal machines, which can seal the web in vertical direction while travelling with moving tube to achieve higher speeds.

SUM MARY OF THE INVENTION

In accordance with the present invention, a vertical vertical form-fill-seal packaging machine of the type in which a film is formed into a tube as it is transferred along a transfer route comprises a verticalsealing device along the transfer route, whereby the verticalsealing device comprises a pair of sealing jaws whichcome into contact with each other to press the both edges of film sealing the film in the verticaldirection thereby forming a tube.

The verticalsealing device is also movable in the transfer direction of the film up to a distance slightly shorter than the length of the sealing jaws. A support member is mounted on the main body of the machine and is capable of supporting a moving plate on which pair of verticalsealing jaws in a direction parallel to the film transfer route is configured for sealing the moving web in vertical direction to form tube from film. The verticalsealing jaws come into contact with, and separate from, each other. According to invention, either one of the vertical sealing jaws is movable and another is fixed or alternatively both the sealing jaws are movable simultaneously moving towards and away from each other. The sealing jaws are movable by an actuating means. The actuating means may be mechanical, pneumatic, electric, hydraulic, rotary or any other actuating mechanism known in the art.

A pair of vertical guides is provided on the support member on which the moving plate makes linear sliding movement in up and down direction parallel to moving direction of the web. Similarly, a pair of horizontal guides is provided on the moving plate on which the vertical sealing jaws make a linear sliding movementin sealing and non-sealing positions. It may be contemplated that the pair of guides does not limit the invention, however, at least one guide is provided to ensure the linear movement of moving members, as described above.

A driver is mounted in the main body of the machine so as to generate a rotary motion. A power transmission mechanism converts the rotary motion generated by the driver into a reciprocating motion in a direction along the film transfer route and transmits it to the moving plate.

The rotary motion generated by the driver mounted on the main body of the packaging machine is converted into a reciprocating motion to move the moving plate in up and down direction thereby causing the vertical sealing device to move along with the sealed web downwards in closed condition and then moving upward in open conditionalong the film transfer route by the contact transmission mechanism and into a reciprocating motion along the film transfer.

Also in the above case the driver is mounted on the main body of the machine so as not to reciprocate together with the verticalsealing devices or the moving plate. The operating velocities of the devices are increased and at the same time, a powerful drive means is not required.

The vertical form-fill-machine further comprises a continuous transverse sealing mechanism, which seals the top of the preceding package in the chain and following package from the bottom. The transverse sealing mechanism employed may be one of as described in Patent application number 1189/DEL/2009 filed by the applicant. In which the sealing jaws move in D type path. BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages and features of the present invention, as well as methods of operation and economies of manufacture, will become apparent to one skilled in the art to which the present invention pertains based upon the following detailed description and the appended drawings, all of which form a part of this application. In the drawings:

FIG. 1 is a schematic side view of the entire structure of a vertical form-fill- seal packaging machine according to an embodiment of the present invention;

FIG. 2 is a detailed view of a verticalsealing device of the vertical form-fill- seal packaging machine of FIG. 1 ;

FIG. 3 is a top view of vertical sealing device of FIG. 2 and movement of sealing jaws; and

FIG. 4 is a diagram illustrating the driving mechanism of the moving plate of the sealing assembly.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 is a schematic side view of a vertical form-fill-seal packaging machine (100) according to a first embodiment of the present invention. The entire structure of a typicalvertical form-fill-seal packaging machine (100) will be described by referring to FIG. 1. The machine (100) is of the type that transfers the film from a roll continuously. Machine (100) includes a pair of right and left frames (103A, 103B) extending from the rear of the machine main body toward the upper portion and then to the front portion thereof. A roll of the film (not shown) is mounted on an unwind at the rear parts of the frames (103A, 103B). The film unwinding from the roll is guided by a plurality of rollersmounted between the frames (103A, 103B)and transferred to the front portion of the main body along the frames (103A, 103B), following a forming path.

A cylindrical chute (108) extending vertically is provided in front of the frames (103A, 103B), so as to allow products to be supplied thereinto from an upper, funnel shaped hopper (108A), and a forming unit (109) of a predetermined shape, surrounding the chute (108) whereby the film transferred along the frames (103A, 103B)is wrapped around the peripheral surface of the chute (108) through the forming unit (109) to be formed into a tube with both side edges folded outwards as fins keeping the inner surface of the film in the fin facing each other. In this state, the film is further transferred downward along the chute (108).

Further, in front of the cylindrical chute (108), there is arranged a vertical sealing device (110)positioned opposite the chute (108) such that the two fins come between the vertical sealing device (110). The vertical sealing device (110) is also movable in the transfer direction of the film. A support member (111) is mounted on the main body of the machine and is capable of supporting a moving plate (112) on which a pair of vertical sealing jaws (113A, 113B) in a direction parallel to the film transfer route is configured for sealing the fins of moving formed tube of film (not shown) in vertical direction to form closed tube from film. The pair of sealing jaws (113 A , 113B) which come in contact with, and separate from, each other to perform sealing of fins. According to invention, either one of the sealing jaw (113A) is movable and another (113B) is fixed or alternatively both the sealing jaws (113 A , 113B) are movable simultaneously which move towards and away from each other. The sealing jaws are movable with an actuating means. The actuating means may be mechanical, pneumatic, hydraulic, rotary, electric or any other actuating mechanism known in the art.

On opposite sides of the cylindrical chute (108), there are provided a pair of right and left feed or traction belts (114A, 114B) which transfer the tubular film on the chute (108). The film unwind from the roll is continuously transferred along the transfer route without excessive tensile force applied thereon, by the continuous driving of the feed belts (114A, 114B). A manual or automatic splicing arrangement may be provided at the roll unwind. Below the cylindrical chute (108), there is provided a transverse sealing device (120) which transversely seals the tubular film hanging down from the chute (108). The transverse sealing device (120) incorporates therein a cutter for cutting or perforator for perforating the sealed band at the central position between the preceding and succeeding bags.

The transverse sealing device (120) is so constructed that it is provided with a pair of sealing jaws (121 , 122) for sealing the tubular film transversely by pressure and heating and moving the film downward while keeping the film clamped to provide necessary dwell time whereby the tube is transversely sealed as it is transferred continuously without stopping the tube every time when it is transversely sealed. Further, subsequent to the transverse sealing of the tube by the transverse sealing device (120), products are fed by gravityin measured quantity into the chute (108) from the hopper (108A) and continuously transferred downward into the tube so as to be sealed transversely and cut / perforated resulting in discharging packed bags in sequence.

Fig 2 and Fig 3. show the detailed view of vertical sealing device (110) according to embodiment of the present invention. The vertical sealing device (110) is movable in the transfer direction of the film. A support member (111) is mounted on the main body of the machine preferably on left frame (103B)and is capable of supporting a moving plate (112) on which pair of vertical sealing jaws (113 A , 113B) in a direction parallel to the film transfer route, is configured for sealing the fins of the moving formed tube, in vertical direction to form closed tube from film. The support member (111) is provided with a pair of guides (117A, 117B) on which the moving plate (112) makes a vertical reciprocating movement in the direction of moving tube. However, the invention is herein described with reference to a pair of guides (117A, 117B) but there can be single guide or more than two guides according to requirement, without limiting the scope of the invention. A driver (130), preferably a servo motor, is mounted on the main body of the machine so as to generate a rotary motion. A power transmission mechanismconverts the rotary motion generated by the driver into a reciprocating motion in a direction along the tube transfer route and transmits it to the movingplate (112)supported by the support member (111). However, the driver (130) may be a stepper motor, linear motor, hydraulic or pneumatic motor or similar devices which can be controlled by a program to synchronise with other moving parts of the machine.

The rotary motion by the driver (130) mounted in the main body of the packaging machine is converted into a reciprocating motion of the moving plate in up and down direction thereby causing the vertical sealing device (110) to move downwards in closed condition along with the fins being sealed and then moving upward in open condition by the contact transmission mechanism and into a reciprocating motion along the film transfer. A flywheel (132) is connected to the driver (130)and the eccentric shaft on the face of the flywheel (132) is connected with the tie rod (134)at its proximal end and the distal end of the tie rod (134) is connected to the moving plate (112).

Also in the above case, the driver is mounted on the main body of the machine so as not to reciprocate together with the vertical sealing device (110) or the moving plate (112). The operating speeds of the devices are increased and at the same time, a powerful drive means is not required. Thevertical sealing device (110) further comprises a pair of sealing jaws (113A, 113B) which come into contact with and separate from each other. According to invention, either one of the sealing jaws (113A) is movable and another (113B) is fixed or alternatively both the sealing jaws (113A, 113B) are movable simultaneously which move towards and away from each other. The sealing jaws (113 A , 113B) are movable with an actuating means (136). The actuating means may be mechanical, pneumatic, hydraulic, rotary, electric or any other actuating mechanism known in the art. The moving plate (112) is also provided with a pair of horizontal guides (119A, 119B) on which the moving jaw (113A) moves in a linear fashion. Fig. 4 shows the mechanism for driving the vertical sealing device (110). The rotary motion of the driver (130) is converted into linear movement. As described with reference to Fig 2 and Fig. 3 above, the flywheel (132) is connected to the driver (130)and the eccentric shaft on the face of the flywheel (132) is connected with the tie rod (134) at its proximal end and the distal end of the tie rod (134) is connected to the moving plate (112). When the flywheel (132) rotates on its axis, the distal end of the tie rod (132) moves up and downwhile proximal end moves over the eccentric shaft.The moving plate (112) is guided over the guides (117A, 117B) can only make linear movement in up and down direction when connected with distal end of the tie rod (134). This causes the vertical sealing device (110) to make an up and down reciprocating movement, in direction parallel to axis of moving web. As described earlier the sealing jaw (113A) is moved horizontally by actuating means (136)towards the fixed jaw (113B) in closed condition for sealing the fins of tube. The jaw (113A) makes a linear motionon a pair of horizontal guides (119 A , 119B). The actuating meansmay be mechanical, pneumatic, hydraulic, rotary, electric or any other actuating mechanism known in the art.

The verticalsealing jaws (113 A , 113B)close and press the fins for sealing and the up and down movement of the moving plate (112) is synchronized such that it moves downwards along with the tube to a distance less than the length of the sealing jaws (113A, 113B)and then open and move upwards by the contact transmission mechanism into a reciprocating motion along the film transfer. The travelling jaws provided longer sealing time and by travelling shorter distance than the length of the jaws the sealing band on the fins get multiple overlapping seals.

The vertical form-fill-machines according to present invention furthercomprise a transverse sealing device which is not described in details. The sealedtubular film hanging down from the cylindrical chute (108)passes downward. As the tube passesthe tube filledwith product is transversely sealed to make packages and cut / perforated by the sealing jaws. The transverse sealing jaws begin to lower as they come into contact with each other pressing the tube and begin to move up after they move away from each other. Then, after continuously moving away from each other as they move up, they only come close to each other at the upper dead point.As a result of these movements, the sealing jaws move downward while they are held in contact with each other and during this period, it is possible to clamp the downwardly moving tubular film for transverse sealing and cutting / perforating by the jaws, without temporarily stopping the transfer of the tubular film.

As described above the transverse sealing mechanism may be as one described in Indian Patent Application Number 1189/D EL/2009.

The linear speeds of traction belts (114A, 114B) which transfer the tubular film on the chute (108), vertical sealing device (110) and the linear speed of transverse sealing device are synchronised with respect to each other to ensure jerk less movement of the web without any stoppage in a continuous motion.

While the present invention has been described in connection with what are currently considered to be the most practical and preferred embodiments, it is to be understood that various arrangements and alternative embodiments are intended to be included within the scope of the appended claims.