Thermoshaping machine

Abstract

A shaping machine has upper and lower shaping tools movable vertically between an open position spaced apart and spacedly flanking a shapable strip passing between them in a generally horizontal travel direction and a closed position gripping the strip and also movable horizontally parallel to the strip between an upstream tool position and a downstream tool position. Upper and lower clamp plates offset horizontally from the shaping tools are also movable vertically between an open and closed positions and movable horizontally between upstream position and downstream clamp positions. Respective drives connected to the tools and plates alternately move the tools and the plates between their open and closed positions. This drive also move the tools and plates downstream in the direction substantially only when in the respective closed positions and moves the tools and plates upstream in the direction substantially only when in the respective open positions.

Description

FIELD OF THE INVENTION

The present invention relates to a thermoshaping machine. More particularly this invention concerns such a machine that is used in, for example, the pharmceutical industry to make a package strip holding pills, capsules, dragees, or the like, and to a method of operating the machine.

BACKGROUND OF THE INVENTION

A standard strip used, for example, to package pills is made by passing a flat thermoplastic strip between a pair of shaping tools, one of which is formed with bumps that fit into complementary recesses on the other. In a standard operation the strip is passed through a heating station just upstream of the shaping tools so that when the strip is engaged by the tools, which are usually cooled, it is soft and can easily be plastically deformed to have the blisters that are subsequently used to hold the product being packaged, e.g. pills. Downstream of the shaping machine the blisters formed in the by-then-cool strip are filled with the mall objects to be packaged, another film or a foil is bonded to the top face of the blister strip to encapsulate the objects, and the strip is cut into pieces each having at least one blister and the encapsulated object.

Thus the shaping machine has an upper shaping tool and a lower shaping tool between which the strip is guided and which are movable relative to one another between an open position and a closed position, and a feeder for the strip. Because of the nature of this production operation it is critical that the strip be conveyed continuously, that is at a constant speed, through the various, stations and machines. This is particularly hard to adapt to the actual blister-forming machine that must open and close on the strip.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved thermoshaping machine.

Another object is the provision of such an improved thermoshaping machine that overcomes the above-given disadvantages, in particular that optimizes the cooperation of the continuously framing strip with the cycled operation of the thermoshaping machine.

SUMMARY OF THE INVENTION

A shaping machine has according to the invention upper and lower shaping tools movable vertically between an open position spaced apart and spacedly flanking a shapable strip passing between them in a generally horizontal travel direction and a closed position gripping the strip and also movable horizontally parallel to the strip between an upstream tool position and a downstream tool position. Upper and lower clamp plates offset horizontally from the shaping tools are also movable vertically between an open position spaced apart and spacedly flanking the strip and a closed position gripping the strip and also movable horizontally parallel to the strip between an upstream clamp position and a downstream clamp position. Respective drives connected to the tools and plates alternately move the tools and the plates between their open and closed positions. This drive also move the tools and plates downstream in the direction substantially only when in the respective closed positions and moves the, tools and plates upstream in the direction substantially only when in the respective open positions.

With this thermoshaping machine for a continuously running strip, the lower shaping tool and the upper shaping tool for the shaping process move along with the strip between the upstream end position and the downstream end position in order to perform the shaping process as soon as the required synchronism is achieved between the upper shaping tool and the lower shaping tool and the strip.

Within the scope of the invention it is particularly preferred when the shaping tools and the feeder are operated alternately, that moved alternately between the closed and open positions during displacement in the direction of travel of the strip in order to produce a continuous advancement of the strip, i.e. the feeder itself need not be permanently active, since part of the time workpiece advance is effected by the shaping tools. In this manner the synchronism is forcedly maintained. In addition, this ensures that the clamping plates may be easily moved between the downstream and the upstream end positions, that is the positions where they switch travel direction, without interfering with advance of the strip or causing unacceptable fluctuations in the web tension.

In the thermoshaping machine according to the invention it is particularly advantageous when the distance between the downstream end position and the upstream end position for the shaping tools and for the clamping plates in each case is greater than the travel of the shaping tools and clamping plates, and includes a synchronization zone for synchronizing with the strip before the change to the closed position. As a result of this design it is not necessary for the clamping plates and the shaping tools to be completely up to speed when they start their displacement between the upstream end position and the downstream end position; rather, there is always an zone in which the shaping tools and the clamping plates are synchronized with the strip. Thus the tools and plates have a chance to accelerate up to the web-travel speed as they move out of the respective upstream and positions and only close when they are up to speed; similarly they disengage from the strip workpiece and have time to decelerate to a stop as they move into the downstream end positions. Such operation makes it possible to move the fairly massive shaping tools and clamping plates without using powerful drive, and greatly reduces shock and wear of the system.

When the shaping tools and/or clamping plates are in the closed positions, that is locked with the blisters formed in the strip, it is also advantageous when the distance between the reversal positions includes a deceleration zone after the interlock is released during the change to the open position. This ensures that, for example, after the strip is shaped and the blisters are formed the bumps provided for this purpose in the upper shaping tool may be completely removed from the forced blisters before the upper shaping tool, and synchronously therewith the lower shaping tool, again loses the synchronism with the advancement of the strip.

It is also within the scope of the invention that the displacement path of the shaping tools between the upstream end position and the downstream end position is smaller than the extension of the shaping tools in the direction of travel of the strip. The thermoshaping machine according to the invention may have a particularly compact design, since it is not necessary for either the shaping tools or the clamping plates to be moved between the upstream and the downstream end positions by a full length of the strip processed in a working cycle. This is because even during the return between the downstream end position and the upstream end position the advance contributes to the change of the strip section located between the shaping tools.

To improve the quality of the blisters formed in the strip, it is within the scope of the invention that at least one of the shaping tools is temperature-controlled, in particular thermally connected to a cooling device, in order to quickly cool the blisters formed by the shaping tools to below the shaping temperature of the strip, thus stabilizing the formed blisters. It is advantageous when in addition at least one of the clamping plates is similarly temperature-controlled, in particular thermally connected to a cooling device. In this manner the strip may continue to be cooled, even when as the result of its continuous motion the strip itself is no longer gripped by the shaping tools.

To allow the greatest possible flexibility in use of the thermoshaping machine even during a format change, a controlled drive is provided in each case for displacing the shaping tools and the clamping plates in the feed direction. For this reason a hydraulically actuated, preferably pneumatic drive is provided for the clamping plates, likewise for the change between the open position and the closed position.

It is also advantageous when the plane of the strip in the thermoshaping machine and the shaping tools and clamping plates aligned parallel thereto define an angle of inclination with respect to the vertical.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 schematically shows a thermoshaping machine according to the invention in a side view, with the shaping tools at the upstream end position and in the open position and the clamping plates in the closed position;

FIG. 2 shows the shaping tools during the acceleration synchronization zone;

FIG. 3 shows the shaping tools in the closed position after the end of the acceleration synchronization zone and the clamping plates likewise still in the closed position;

FIG. 4 shows the shaping tools in the closed position and the clamping plates in the open position;

FIG. 5 shows the shaping tools in the closed position and the clamping plates in the open position during the return from the downstream end position to the upstream end position;

PIG. 6 shows the shaping tools in the closed position and the clamping plates in the open position at the upstream end position;

FIG. 7 shows the shaping tools and the clamping plates in the closed position;

FIG. 8 shows an illustration corresponding to FIG. 1, with the shaping tools in the open position in the deceleration zone and the clamping plates in the closed position; and

FIG. 9 shows the shaping tools in the open position at the downstream end position and the clamping plates in the closed position after completion of their acceleration up to travel speed.

SPECIFIC DESCRIPTION

As seen in FIG. 1 a thermoshaping machine 1 for a strip W is conveyed from a supply roll through a heating station 17 in order to heat the strip W to a shaping temperature and to shape the strip W in the thermoshaping machine 1 located downstream from the heating station in the direction of travel 11 of the strip W. For this shaping the thermoshaping machine 1 has an upper shaping tool 2 and a lower shaping tool 3 between which the strip W is guided. The lower shaping tool 3 and the upper shaping tool 2 are movable relative to one another by at pneumatic actuator 12 between an open position (FIGS. 1, 2, and 9) and a closed position (FIGS. 2 and 3, 4, 5, 6, and 7). In the closed position blisters B are molded in the strip W, generally by bumps provided in the upper shaping tool 2 which penetrate the strip W, supported by the lower shaping tool 3 that has cavities for accommodating the bumps.

In the thermoshaping machine 1 it is necessary to move the strip W conveyed from the heating station 17 to the subsequent station in the thermoforming machine. For this purpose a feeder 4 which is also associated with the thermoshaping machine has an upper clamping plate 5 and a lower clamping plate 6 which are movable relative to one another between an open position (FIGS. 4, 5, and 6) and a closed position (FIGS. 12 and 3, 4, 7, 8, and 9) by another pneumatic actuator 13. In this respect the clamping plates 5 and 6 may be displaced in the sane manner as the shaping tools 2 and 3.

The thermoshaping machine 1 according to the invention provides for special coordination between the shaping tools 2 and 3 and the clamping plates 5 and 6 that can be moved in a precisely coordinated manner between respective upstream end positions 7 and 8 and downstream end positions 9 and 10 parallel to the direction of travel 11 of the strip W, thereby continuously advancing the strip W at a constant speed with an alternating operation in the closed position during displacement in the direction of travel 11 of the strip W. The tools 2 and 3 and the plates 5 and 6 have a length L₁ in the direction 11 that is substantially longer than a length L₂ in the direction 11 through which they travel between their upstream and positions 7 and 8 and downstream end positions 9 and 10 to ensure proper gripping, shaping and cooling of all of the strip.

This dimensioning also makes possible an acceleration synchronization zone for synchronizing with the tools 2 and 3 and the plates 5 and 6 with strip W before the change to the closed position. There is also a deceleration zone in the change to the open position and complete stopping of the tools 2 and 3 and plates 5 and 6. The tools 2 and 3 are shifted in the direction 11 by a variable-speed servomotor drive 14 and the plates 5 and 6 by another drive 15.

Lastly, it is noted that at least one of the shaping tools 2 and 3 and at least one of the clamping plates 5 and 6 is temperature controlled, in particular thermally connected to a cooling device 16, in order to quickly cool the strip W heated in the heating station to below the shaping temperature after the shaping and to stabilize the blisters formed in the thermoshaping machine 1 between the shaping tools.

A complete cycle in the thermoshaping machine 1 during the continuous feed of the strip W is briefly described below, with reference to FIGS. 1 through 9. FIG. 1 shows the shaping tools 2 and 3 in the open position at the upstream end position 8 at the beginning of a cycle, while the clamping plates 5 and 6 are in the closed position and advancing the strip W as a result of the lowered upper clamping plate 5. Starting from this FIG. 1 position, during the acceleration synchronization zone shown in FIG. 2 the shaping tools 2 and 3 are accelerated to the speed of the strip W, while the clamping plates 5 and 6 in the feeder 4 continue the advancement unchanged at this speed.

FIG. 3 shows the position in which the shaping tools 2 and 3 at the end of the synchronization zone have reached the speed of the strip W on displacement in the direction 11 toward the downstream end position 9, so that the shaping tools 2 and 3 are shifted from the open position to the closed position and thus become active. The clamping plates 5 and 6 are likewise still active in order to achieve a switchover from using the plates 5 and 6 to drive the strip W to using the dies 2 and 3 to drive it without any fluctuation in the web tension.

In FIG. 4 the changeover is completed, and the shaping tools 2 and 3 continue to form the blisters and take over the advancement, whereas the clapping plates 5 and 6 are open and decelerating. In FIG. 5 the clamping plates 5 and 6 have reached and stopped in their downstream end position 10 after passing through the deceleration zone, while the shaping tools 2 and 3 continue mold and cool the strip W and also displace it in the direction 11.

FIG. 6 shows the position in which the clamping plates 5 and 6 have returned to their upstream end position 7 and are still open, whereas the shaping tools 2 and 3 continue to feed and cool the strip W. FIG. 7 shows the position in which advance once again starts to change, with the shaping tools 2 and 3 as well as the clamping plates 5 and 6 in the closed position.

FIG. 8 shows the displacement of the shaping tools 2 and 3 to the downstream end position and open position after they have stopped at the downstream end of the deceleration zone. The clamping plates 5 and 6 have once again sole responsibility for advance of the workpiece W after having themselves finished travel through the acceleration synchronization zone. Last, FIG. 9 shows the shaping tools 2 and 3 at the downstream end position 9 at the end of the deceleration zone, before the shaping tools 2 and 3 return to the upstream end position 8 and start a new working cycle in the thermoshaping machine 1 for the continuously running strip W and the plates 5 and 6 are moving downstream at the workpiece travel speed.

Claims

1. A shaping machine comprising: upper and lower shaping tools movable vertically between an open position spaced apart and spacedly flanking a shapable strip passing between them in a generally horizontal travel direction and a closed position gripping the strip and also movable horizontally parallel to the strip between an upstream tool position and a downstream tool position; upper and lower clamp plates offset horizontally from the shaping tools and movable vertically between an open position spaced apart and spacedly flanking the strip and a closed position gripping the strip and also movable horizontally parallel to the strip between an upstream clamp position and a downstream clamp position; and drive means connected to the tools and plates for alternately moving the tools and the clamp plates between their open and closed positions and for moving the tools and plates downstream in the direction substantially only when in the respective closed positions and for moving the tools and plates upstream in the direction substantially only when in the respective open positions.

2. The machine defined in claim 1 wherein the drive means alternately closes and opens the shaping tools and clamp plates so as to advance the strip continuously in the direction.

3. The machine defined in claim 1 wherein the drive means shifts the shaping tools and clamping plates into the respective closed positions after some advance downstream from the respective upstream end position and out of the respective closed positions somewhat upstream of the respective downstream end positions, whereby the tools and plates have time to accelerate to a travel speed when starting movement downstream from the respective upstream end positions and have time to decelerate to a stop when moving into the respective downstream end positions.

4. The machine defined in claim 1 wherein the shaping tools have a length parallel to the direction and engageable with the strip that is greater than a maximum travel of the tools in the direction between the respective upstream and downstream positions.

5. The machine defined in claim 1, further comprising cooling means connected to the tools.

6. The machine defined in claim 1, further comprising cooling means connected to the plates.

7. The machine defined in claim 1 wherein the drive mesas includes variable drives effective in the direction for displacing the plates and tools in the direction.

8. The machine defined in claim 1 wherein the drive means includes fluid-powered actuators effective vertically for displacing the plates and tools between the respective open and closed positions.

9. The machine defined in claim 1 wherein the transport direction extends at a small acute angle to the horizontal.