Sealing machine for cardboard boxes with two superposed sealing units and simplified access to the lower sealing unit

Abstract: There is described a sealing machine with two superimposed sealing units for parallelepiped boxes with down-turned flaps with simplified access to the lower sealing unit. It comprises a lower supporting and containment structure (31), wherein there is housed a lower sealing unit (34) and that defines a supporting plane (1) of the boxes, means (2) of advancement of the boxes along said supporting plane (1) and an upper supporting structure (32) that can be displaced vertically on which there is fastened an upper sealing unit (35). Said lower supporting structure (34) is provided with means (13), such as pneumatic cylinders, suitable for allowing the upward movement of said lower sealing unit (34) above said supporting plane (1) of the boxes. Similar means (14) are preferably provided for the prior upward movement of the upper supporting structure (32) in a position such as to avoid its collision with the lower sealing unit (34). The supporting plane (1) preferably comprises a removable part (37) for gaining access to a feed roll of sealing material (38) of the lower sealing unit (34).

Description: The present invention relates to a sealing machine with two superimposed sealing units for parallelepiped boxes with down-turned flaps with simplified access to the lower sealing unit. Sealing machines are known to be units used to seal the top and the bottom of cardboard boxes for which the closing flaps have already been turned down. Numerous machines are known that carry out such sealing by using sections of plastic adhesive tape taken from a continuous roll. However, ecological reasons have recently oriented some users, and consequently the manufacturers, toward sealing machines that use suitably moistened gummed paper instead of adhesive tape. As described, for example, in the US patent No. 4,554,042 and in the Italian patent application No. MI92A000407 dated 25 February 1992, known sealing machines comprise a supporting base, means for the advancement of the boxes associated with said supporting base, as well as two sealing units, one upper and one lower, used for sealing the upper and lower surfaces of the boxes, respectively. Such sealing units are constructed in a different manner according to the type of sealing material (gummed paper or adhesive tape) used, but they are in any case generally designed so that it is the box itself that automatically determines the withdrawal, the cutting and the application of the correct length of adhesive tape or gummed paper. In the known sealing machines the upper sealing unit is located above a base for supporting the boxes in a vertically displaceable manner, so that the sealing machine can be adapted to boxes of different heights; the adjustment in height of the upper sealing unit can be executed automatically by the machine by means of special devices or manually at each change of size of the box. The lower sealing unit, on the other hand, is permanently housed in a space provided in the supporting base. As regards the structure of the two upper and lower sealing units reference is made in particular to the abovementioned Italian patent application and to the European patent No. 0179520 for sealing with gummed paper and with adhesive tape, respectively. In sealing machines of the conventional type there are several drawbacks linked with maintenance operations, in particular as regards the lower sealing unit, since this is located inside the supporting structure of the sealing machine and can thus be reached by the operator only with difficulty. The abovementioned drawback refers both to operations of extraordinary maintenance (possible breakdowns, jamming of the adhesive tape or of the gummed paper, etc.), and those of ordinary maintenance (replacement of the adhesive tape or of the gummed paper, cleaning the machine, etc.). The object of the present invention is to accomplish a sealing machine wherein access to the lower sealing unit for the corresponding maintenance operations is decidedly simplified. According to the present invention such object is attained by means of a sealing machine comprising a lower supporting and containment structure, wherein there is housed a lower sealing unit and that defines a supporting plane of the boxes, means of advancement of the boxes along said supporting plane and an upper supporting structure that can be displaced vertically on which there is fastened an upper sealing unit, characterized in that said lower supporting structure is provided with means that can be operated from the outside, suitable for allowing the upward movement of said lower sealing unit above said supporting plane of the boxes. It appears evident that in this way a sealing machine is obtained for which operations of maintenance on the lower sealing unit are simplified due to the effect of the greater accessibility of the abovementioned unit on the part of an operator. In this respect it should be noted that, according to a preferred embodiment, the upward movement of the lower unit is subordinated to a prior upward movement of the upper unit, whose subsequent downward movement is, on the other hand, subordinated to the subsequent downward movement of the lower unit; it follows that it is impossible for the upper sealing unit and the lower sealing unit to be damaged as a consequence of an impact between them. In addition, in the machine according to the invention it is preferably provided for that the supporting plane for the boxes include a part that may be extracted suitable for making it easier to gain access to the roll of sealing material (adhesive tape or gummed paper), simplifying in this way operations also related with the replacement of the roll itself. These and other features of the present invention shall be made more evident by the following detailed description of one of its embodiments, illustrated as non-limiting examples in the enclosed drawings, wherein: Fig. 1 represents a sealing machine according to the invention in a longitudinal sectional view, in conditions of rest; Fig. 2 represents the same machine, sectioned along the line II-II of Fig. 1; Fig. 3 represents the same machine in a longitudinal sectional view as in Fig. 1, with the upper sealing unit displaced vertically upward; Fig. 4 represents the same machine, again in a longitudinal sectional view, with the lower sealing unit extracted from its position; Fig. 5 represents the pneumatic operating and control diagramme of the movement of the two sealing units. With reference to Fig. 1, the sealing machine according to the invention comprises essentially a lower structure 31 for the support and containment of a lower sealing unit 34. Over such structure 31 there is superimposed a roller frame 1 that defines a supporting plane for the boxes to be sealed, at the two sides of which there are two belt units 2 for advancing the boxes. There is also an upper structure 32, for the support of an upper sealing unit 35. Said upper structure 32 can be displaced vertically to arrange itself at a variable distance from said roller frame 1, so as to allow the insertion of a box to be sealed between the upper structure 32 and the roller frame 1. The lower sealing unit 32 and the upper one 35 have the task of applying a strip of adhesive tape, or equivalently of moistened gummed paper, along the slits that separate the closed lower and upper lateral flaps of the bottom and of the top of the boxes. The structure of said lower 34 and upper 35 sealing units, known in itself, for example from the European patent No. 0179520 and from Italian patent application No. MI92A000407 dated 25 February 1992, shall not be described here in detail; it is in any case worth while noting that they generally comprise a roll 38 of gummed paper or adhesive tape and a main casing 39, comprising various mechanisms for feeding and applying the sealing material. The roller frame 1, superimposed over the lower containment structure 31 at the latter's upper surface, can be summarily split into two main portions, 36 and 37, of which the first is fixed and the second can be extracted. Both the portions 36 and 37 are constituted by a succession of idle rollers 40 that make it easy to cause the advancement of the boxes, determined by the pair of lateral belts 2, superimposed over the frame 1 and that can be brought closer to one another by operating a crank 44 (Fig. 2) to engage with opposite sides of the boxes. In the case of the removable portion 37, placed in a position superimposed over the feeding roll 38 of the lower sealing unit 34, said rollers 40 are mounted on a small supporting frame 41, that can be extracted to allow an operator to gain easy access to the roll 38. In the case of the fixed portion 36, at the position of the upper sealing unit 35, there is a window 30 (Fig. 2), that defines a space to receive the lower sealing unit 34. The upper supporting structure 32 can be displaced vertically along two lateral uprights 21 under the effect of its own weight, that tends to keep it at the position of minimum height, and by a pair of threaded vertical bars 11 (Fig. 2) that, if suitably operated through a crank (not shown) on the top of the same, are capable of raising it to the desired height to allow the passage of the boxes. The sealing machine according to the present invention is further provided with a pair of pneumatic lifting cylinders 13, provided with stem 42, suitable for executing the upward movement of the lower sealing unit 34 from the position of Fig. 1 and for this purpose arranged vertically inside the lower supporting structure 31 at the intervals between the rollers 34 of the part 36 of the roller frame 1 and fastened to such structure through pivots 20. Parallel to such cylinders 13, but externally to the structure 31, there is also a second pair of pneumatic Lifting cylinders 14, each provided with stem 43 connected to the upper supporting structure 32. The two pneumatic cylinders 13 and 14 can be connected to a source of compressed air or to discharge, according to the operating conditions, thanks to a pneumatic operating and control circuit 12 that is represented in detail in Fig. 5. Such pneumatic circuit 12 can be split summarily into two main constituent parts 15 and 16. Of these the first 15 is directly accessible by the operator through a manual selector 3 that can be operated from the outside and that receives its own power from a conduit 318; the second 16, on the other hand, is powered and controlled by the abovementioned first part, with which it communicates through a conduit 51, and is powered through a branch 19 of the conduit 18. The part 15 of the pneumatic circuit 12 comprises, in addition to the abovementioned selector 3, a first two-way valve 4, provided with a feeler 45 for checking the position of the lower sealing unit 34, a second two-way valve 6 provided with a feeler 46 for checking the position of the upper supporting structure 32, and two flow regulators 7 and 29 provided with check valves. The selector 3 is connected to the first two-way valve 4 through a first conduit 50, and to the second 6 through a conduit 53. The first valve 4 is also further connected to the part 16 of the circuit through the conduit 51; the second valve 6 is, on the other hand, further connected through a conduit 54 to the two cylinders 13, upstream and downstream from which there are the two flow regulators 7 and 29, respectively. The second part 16 of the pneumatic circuit 12 comprises, on the other hand, a two-way valve 5, powered by the branch 19 of the conduit 18, and a flow regulator 28, connected together and to the cylidners 14 (positioned downstream from said flow regulator 28) through a conduit 52. The operation of the sealing machine illustrated in the drawings is not described here, being of a widely-known type, for example as described in the European patent and in the Italian patent application mentioned earlier. As regards access to the lower sealing unit for operations of maintenance and reloading the same, the sealing machine according to the present invention is, on the other hand, different from known machines in that it works as follows. The upward movement of the two sealing units can be operated, as already mentioned, through the pneumatic circuit 12 illustrated in Fig. 5 The pneumatic circuit 12 can be activated and powered by the operator through the manual selector 3, that can have three positions, indicated in the figure with 8, 9 and 10, respectively, and corresponding to keeping the two units at rest (Fig. 1), to the upward movement of the upper sealing unit (Fig. 3) and the upward movement of the lower sealing unit (Fig. 4). With reference to Fig. 5, when the selector is in position 8, compressed air introduced through the conduit 18, through the conduit 50, can reach the two-way valve 4 that, through the feeler 45, checks the position of the lower sealing unit 34. Since this is in the at rest position, that is, it is inside the receiving space 30, the abovementioned valve 4 is consequently in position 26 and allows the passage of compressed air that, through the conduit 51, reaches the valve 5. The latter can assume the two positions 22 and 23, corresponding to the condition of rest (Fig. 1) and to the upward movement of the upper sealing unit 35, respectively, (Fig.s 3 and 4), and remains in position 22 until compressed air is present in conduit 51. In such a condition conduit 52 is connected to discharge and cylinders 14 are not activated. The same, on the other hand, can be said as regards conduits 53 and 54, that are both connected to discharge, the first because selector 3 is in position 8 and the second because valve 6, detecting the lowered condition of the upper supporting structure 32 with the feeler 46, is in position 24 as shown in Fig. 5. Thus cylinders 13 are also not activated. When selector 3 is in the position indicated with 9 in Fig. 5, conduit 50 and, thus, 51 are connected to discharge, while power conduit 18 is closed. This causes the displacement of valve 5 to position 23. It follows that conduit 52 can now receive compressed air from the power source 19 and move it to the cylinders 14 thus causing the upward movement of the upper supporting structure 32 of the sealing machine through the upward movement of stems 43 (Fig. 3). Already in this position, by taking away the removable part 37 of the roller frame, it is possible to gain access to the roll 38 of the lower sealing unit 34 for it to be replaced if finished. Following the upward movement of such structure 32, the feeler 46 of the valve 6 is no longer in contact with the structure itself and as a consequence it causes the displacement of the operational position of the two-way valve 6, that goes from the initial position indicated with 24 to that indicated with 25 in Fig. 5, that connects the conduits 53 and 54 together. In this way, when the operator further moves selector 3 by taking it to position 10, compressed air from conduit 18 and moved through conduit 53 can reach conduit 54 and, from here, cylinders 13 which thus cause the upward movement of the lower sealing unit 34 (Fig. 4). The upward speed of the lower sealing unit 34 is regulated through the flow regulator 29. The prior upward movement of the upper supporting structure 32 allows the lower sealing unit 34 to leave freely its receiving space 30, avoiding any danger of collision. The upward movement of the lower sealing unit 34, detected by feeler 45 of valve 4, causes the displacement of valve 4 from position 26 to position 27. In this position valve 4 closes conduit 50 and connects conduit 51 directly to discharge; it follows that, if by mistake the operator takes selector 3 back to position 8 before the cylinders 13 are lowered, valve 5 cannot under any circumstance move to position 22, so that the cylinders 14 and, thus, the upper supporting structure 32, remain raised above supporting plane 1 with no risk of collisions between the upper sealing unit 35 and the lower sealing unit 34. In this condition (Fig. 4) it is possible to gain access freely and with ease to the two sealing units 34 and 35 for maintenance operations of any kind. When the removable part 37 of the roller frame 1 is taken away it is possible, on the other hand, to gain easy access to the roll 38 of the lower sealing unit 34 for its replacement if finished. To return the machine to the normal operating condition it is necessary to go through the steps described up to now in the opposite direction, that is moving selector 3 first to position 9, then to position 8. Displacement to position 9 connects cylinders 13 to discharge, that return to the at rest position, and consequently cause the lower sealing unit 34 (Fig. 3) to move downward, at a speed regulated by the flow regulator 7. The feeler 45, once again in contact with the lower sealing unit 34, again takes two-way valve 4 to the initial position 26. If selector 3 is further moved to position 8, compressed air is once again introduced in conduit 50 and taken through conduit 51 to valve 5, that is once again placed in position 22, thus connecting cylinders 14 to discharge. These slowly lower the upper supporting structure 32, discharging through flow regulator 28 (Fig. 1). The displacement of the supporting structure 32, detected by feeler 46, is followed by the return of the two-way valve 6 to the initial position 24.

Claims: Sealing machine with two superimposed sealing units for parallelepiped boxes with down-turned flaps, comprising a lower supporting and containment structure (31), wherein there is housed a lower sealing unit (34) and that defines a supporting plane (1) of the boxes, means (2) of advancement of the boxes along said supporting plane (1) and an upper supporting structure that can be displaced vertically (32) on which there is fastened an upper sealing unit (35), characterized in that said lower supporting structure (34) is provided with means (13) that can be operated from the outside, suitable for allowing the upward movement of said lower sealing unit (34) above said supporting plane (1) of the boxes. Sealing machine according to claim 1, characterized in that it comprises further means (14) that can be operated from the outside for the upward movement of said upper supporting structure (32) in a position such as to avoid its collision with the lower sealing unit (34) on the occasion of the latter's upward movement above said supporting plane (1). Sealing machine according to claim 2, characterized in that it comprises means (4, 6) suitable for subordinating the upward movement of said lower sealing unit (34) to the upward movement of said upper supporting structure (32) and to subordinate the subsequent downward movement of said upper supporting structure (32) to the subsequent downward movement of said lower supporting structure (34). Sealing machine according to claim 3, characterized in that said means (13, 14) for the upward movement of said lower sealing unit (34) and of the upper supporting structure (32) are constituted by pairs of pneumatic cylinders (13, 14) supported by said lower supporting structure (31) and functionally controlled through a pneumatic circuit (12) comprising said subordinating means (6) and a manual control selector (3). Machine according to claim 4, characterized in that said pneumatic circuit (12) comprises two sub-structures (15, 16), powered through corresponding conduits (18, 19), of which the first (15) suitable for the operation of said cylinders (13) for the upward movement of the lower sealing unit (34), the second (16) suitable for the operation of said cylinders (14) for the upward movement of said upper supporting structure (32), such sub-structure (15) being provided with two-way valves (4, 6) with feelers (45, 46), suitable for subordinating the upward movement of said lower sealing unit (34) to that of said upper supporting structure (32) and for subordinating the downward movement of said upper supporting structure (32) to that of said lower sealing unit (34). Machine according to claim 1, characterized in that said supporting frame (1) is constituted by two portions (36, 37), of which the first is fixed and the second can be removed, located so as to allow access to a feed roll (38) of gummed paper or adhesive tape of the lower sealing unit (34) for its replacement.

Inventors: MARCHETTI AUGUSTO, MARCHETTI, AUGUSTO
Applicants: MARCHETTI AUGUSTO, MARCHETTI, AUGUSTO
Application year: 1993
Main classification: B65B51
IPC codes: B65B51