Printing Apparatus for Use on Plastic Containers

1. Field of the Invention

This invention relates to printing machines for labeling plastic containers, and, more particularly, to head construction for supporting the dies or markers. It can be used to decorate or mark plastic surfaces other than containers.

2. Description of the Prior Art

Prior printing machines usually include a reciprocable ram having a head located at its lower end for supporting a marker or die. An anvil is mounted in a suitable block beneath the head for retaining a workpiece in an operable position. A film having a layer of coating material, such as an alkali metal or marking pigment, is inserted between the marker and the workpiece. The marker or die is heated and functions to release the coating material depositing it on the surface of the workpiece. Although such devices are used extensively, they suffer various shortcomings severely limiting their utilization for container labeling. A major constraint of these machines is that they are relatively large and bulky, and usually operable on limited types of workpieces such as flat objects or plastic wire. Many plastic bottles and containers are unsuitable on such machines for assembly line production. The reason for the problem lies in the head construction of the apparatus. In prior devices the heads are rigidly mounted on the machine and are unable to function resiliently and automatically with the work piece, so as to conform to the configuration of the printing surface. As a result, upon contacting the workpiece, the dies do not adjust to the contour of the work piece nor compensate for any misalignment. Many bottles won't fit or go through the machine. Furthermore, prior devices did not have the capability of individually controlling the temperature of each of the dies which is undesirable because of the different heating characteristics of the various dies and color plates.

The invention described herein cures the above-mentioned inadequacies of prior devices by providing a printing apparatus that is self-adjusting and adaptable to many printing surfaces. The back plate or conformity is measured and made for the size and pattern container for mass labeling. The apparatus includes a back plate integrally connected to a ram. Each die may be mounted on a block containing a cartridge heater which can be individually, thermostatically controlled. The die is integrally connected to each heater enabling heat to be conducted thereto. The distance between the heating block and die surface (as well as a bit of insulation) protects the printing surface and prevents color waves between letters. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description and accompanying drawing.

FIG. 1 is a front perspective view of the printing apparatus incorporating the present invention;

FIG. 2 is a side perspective view of the printing apparatus shown in FIG. 1, showing a container in printing position;

FIG. 3 shows a curved back conformity designed to meet a curved printing surface, and the insert heater position;

FIG. 4 shows a window framing die holder attachment; and

FIG. 5 shows a permanent magnet and holder attachment.

FIG. 1 shows a printing apparatus in the direction of arrow 10 for labeling a curved surface. A backing member in the form of a triangular aluminum back plate 13 yields stability. The curved aluminum front of the back plate 13 presenting a frontal surface has been measured and made the correct size for assembly line printing of a curved work piece in the form of the containers 11 having curved surfaces as illustrated. Die members such as dies 14, 15, 16, and 17 extend at radii from the back plate surface, each the same measured length to contact the printing surface correctly as herein after defined. A resilient member, e.g., a resilient padding 20 which is also flexible in its nature, for each die compensates for the minute differences in bottles made from the molds of a given size, the plastic surface itself and variation in alignment. An attachment above the line of printing is illustrated by 18. A decoration 19 can be placed away from the printing line. Cartridge heaters, or other forms of heater assemblies, 23 are shown inserted in each of the blocks 22. The leads, such as lead pair 24, of the heaters are connected to a temperature controller 25. Should the same temperature be desired for all die and decoration a variator only can be used. The flat surface dies are integrally attached to the heater blocks with silver solder and hence are in heat transfer relationship therewith.

FIG. 2 shows the same printing apparatus against a workpiece such as container 11. A sheet of printing material which may adopt the form of a web of cellophane 26 is coated with a heat sensitive material, that is a formula that prints on the plastic in the pattern and shape of the heated die surface and where the heat sensitive material is disposed toward the container. Foam rubber is used for the resilient padding 20 and there is an insulation member, such as a layer 21 of insulation between the heater block and the padding. Insulation is also used on top the heater blocks and contingent to the sides of the hot die. The workpiece featured here is a cylindrical plastic bottle the size of a typical cleanser bottle. A rod 12 operably connected to a motor, air cylinders, or other motive means (not shown) enables the printing device to reciprocate, and which rod 12 and air cylinder constitute a motive means. When the motive means moves the die member into registry with the work piece, it compresses a portion of the sheet of printing material into the work piece. Thus, the heated die member causes the area of heat sensitive material overlying the die member to be released from the sheet of printing material and disposed on the work piece. If it is desired to print both sides of the plastic surface at the same then two such apparatuses would be used simultaneously both operated automatically with the same motor timing.

An important advantage of the coupling is that its resiliency limits the amount of pressure exerted on the workpiece enabling the dies to orient to the contour of the bottle and to compensate for misalignment.

Individual thermostat control is important when different colors are used on the same workpiece simultaneously, because different color and design may require or optimally operate with different amounts of heat.

Another advantage is the adaptability of printing or decorating on different areas of a container at the same time by vertical or slanted pieces attached to the same back piece. A snowflake, star or other decoration, for examples, can be placed above the printing line and yet operate simultaneously with the letter die.

FIG. 4 shows a die holder attachment window framing each cartridge heater. The window frame die holder allows the die enough movement to adjust to the bottle but not enough movement in any direction to lose the alignment. The frame surrounding each heater block is denoted by No. 27.

FIG. 5 shows a permanent magnet No. 28 and holder attachment No. 29. Four of these are used, one on each side of the die member arrangement. The measured pull, permanent magnets have a screw adjustment at the back No. 30 and as the magnets are moved back or forward within the cases this serves to increase or decrease die pressure on a given side of the bottle. The holder attachment mounts as illustrated by No. 31.

It should be noted that various modifications, such as using other universal coupling means, or a different type of die holder or a support rod can be used while remaining within the purview of the following claims. Moreover, the dies can be attached in different positions to enable the apparatus to print or decorate on different spots on one surface simultaneously. The features of the present invention which are believed to be novel are set forth with particularity in the appended claims.