Release-Coated Packaging Tooling

Abstract

Tooling for a tray-sealing machine is coated with an electroless metal release coating. The coating is applied over the surface of the severing knives and/or clamp of the tooling that is utilized with the tray-sealing machine that comes into contact with a lidding material film used by the machine and penetrates into the surface of the tooling to be integrally formed in the tooling. The coating prevents any of the lidding material film used in forming a cover on the tray from adhering to the knives or the clamp during operation of the machine.

Description

FIELD OF THE INVENTION

The present invention relates to packaging tooling, and more specifically to tooling utilized to sever a thermoplastic web sealed to a tray containing a product to form a cover for the tray in which the tooling includes a release coating.

BACKGROUND OF THE INVENTION

In many industries, and in particular the food processing industry, often times products are packaged in formed plastic trays for sale to consumers. Most often, when products are packaged in trays of this type, the product is covered and retained within the tray by a cover formed of a thermoplastic or other lidding material secured to and around the periphery of the tray.

The products and covers are positioned within and/or around the trays in a continuous process utilizing tray-sealing machines, which are well known in the art. In these machines, as a tray that has been filled with a product moves towards a sealing station of the machine, a thermoplastic or other lidding material film is directed downwardly towards the tray to position and align the web over the open end of the tray. The film is then sealed against the periphery of the tray over the open end by a conventional sealing member or clamp, thereby properly forming the web as a cover over the tray. After the film is sealed against the tray, a heated knife is moved downwardly around the clamp to sever the lidding film around the periphery of the tray, completing the formation of the cover on the tray.

Due to the properties of the lidding materials utilized to form the cover film, when these films are contacted by the heated knife, the heat of the knife causes the film to soften and/or melt at the point of contact with the knife, making it easier to sever the film at the desired location. However, heating the film with the knife to melt the film also causes the melted film to adhere to the knife, which is typically formed of a metal. Over time, the buildup of the melted film material on the knife causes the knife to lose its ability to sever the film cleanly around the tray, resulting in irregular or defective covers on the trays. Thus, the knives need to be cleaned at regular intervals in order to maintain the proper formation of the covers on the trays by the knives. This problem of film buildup also occurs on the clamp and other parts of the packaging machine for the same reasons, necessitating cleaning of these parts of the tooling as well. The time and effort required for this cleaning and the loss of production time for the machine are highly undesirable.

As a result, it is desirable to develop a packaging machine and tooling therefore which is capable of greatly reducing and/or eliminating the build up of lidding film material on the tooling in order to enable the machine to run continuously for an extended period of time without having to stop the machine to remove any build up of the lidding film from the tooling. It is also desirable that the packaging machine tooling be formed such that any build up of lidding film on the tooling can be more easily removed, greatly reducing the time needed to remove any film build up on the tooling, and thus reducing the downtime for the machine.

SUMMARY OF THE INVENTION

According to a primary aspect of the present invention, the severing tooling for a packaging machine is formed with an electroless metal coating deposited on the exterior surface of the tooling. These types of coatings are often used on wear parts due to their significant wear resistance properties. However, these types of coatings have also been shown to unexpectedly function as a non-stick or release layer on the severing tooling to substantially reduce the adherence of any lidding film materials to the tooling, consequently greatly reducing the formation of any film build up on the tooling. The electroless metal coating formed on the tooling does not affect the ability of the tooling to be heated, specifically the knife utilized to sever the thermoplastic film around the periphery of the tray, while providing the release properties to the knife. When using tooling that has been coated in this manner, the length of time that a packaging machine can be run continuously before any cleaning of the tooling of the machine is required is increased significantly compared to non-coated tooling. Furthermore, because the release layer enables any lidding film buildup which has occurred on the tooling to be more easily removed when necessary, the useful life of the tooling is also greatly extended, while the downtime of the machine required when cleaning the tooling is greatly reduced.

According to another aspect of the present invention, the release coating or layer can be applied to the tooling in a manner which evenly covers the tooling to maintain the proper tolerances between the different parts of the tooling. Specifically, the material utilized in and thickness required for the coating to be effective as a release layer can be applied to be sufficiently thin as to prevent different portions of the tooling from coming into contact with one another while the tooling is in use.

According to still another aspect of the present invention, the coating material utilized can be applied to the to the tooling in a manner that integrates the coating material within the material forming the tooling, such that the coating does not constitute a separate layer on the exterior surface of the tooling, but essentially changes the attributes of the material to provide a release attribute to the surface of the tooling material.

Numerous other features, advantages and aspects of the present invention will be made apparent from the following detailed description taken together with the drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode currently contemplated of practicing the present invention.

In the drawings:

FIG. 1 is a side plan view of a tray sealing machine utilizing severing tooling including the release coating of the present invention;

FIG. 2 is a perspective view of the tooling of FIG. 1;

FIG. 3 is a side perspective view of a clamp used in the tooling of FIG. 1;

FIG. 4 is a top perspective view a knife ring used in the tooling of FIG. 1;

FIG. 5 is a perspective view of a knife set used in the tooling of FIG. 1; and

FIG. 6 is an isometric view of a strip heater used in the tooling of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference now to the drawing figures in which like reference numerals designate like parts throughout the disclosure, a tray sealing machine is illustrated generally at 10 in FIG. 1. The machine 10 includes a conveyor 12 on which a number of trays 14 filled with a product (not shown) move towards a sealing station 26. The sealing station 26 includes a roll 16 of a suitable lidding material 18 that is directed from the roll 16 over the trays 14 by rollers 20. The film 18 from the roll 16 is sealed to the trays 14 and separated from the remainder of the roll 16 by tooling 30 movably attached to the station 26, such as by a vertically moving piston 22 operate in conjunction with the conveyor 12 by a motor 24, for example. The machine 10 on which the tooling 30 is utilized can be any type of sealing machine that may also provide other functions, such as forming the tray 14, or filling the tray 14 with a product. Suitable machines that have these capabilities and with which the tooling 30 of the present invention can be utilized include machines sold by Ross Industries, of Midland, Va., G. Mondini S.P.A. of Cologne, Italy, Koch Equipment LLC, of Kansas City, Mo., and Ulma Packaging of Onati, Spain, among others.

Referring now to FIGS. 2-6, the tooling 30 includes a knife ring 40, a knife set 50, a strip heater 60, and a clamp 90. The knife set 50, as best shown in FIGS. 2 and 5, is formed of a pair of knives 70. Each knife 70 has a generally rectangular shape corresponding to the shape of the tray 14 to which the film or barrier lidding material 18 is to be secured by the machine 10, but can have any shape desired depending upon the particular configuration for the tray 14. Each knife 70 is formed with a peripheral wall 72 having an upper end 74 and a lower end 76. The upper end 74 includes a member of spaced apertures 75 used to secure the knives to the knife ring 40. The lower end 76 is formed with a number of teeth or serrations 78 along the entire length of the lower end 76 in order to enable the knife 70 to more easily sever the lidding material 17 upon contact of the lower end 76 of the knife 70 with the lidding material 17.

Each knife 70 is preferably formed of a rigid material, such as a metal, and more preferably stainless steel, which is strong and durable enough to withstand the normal use and wear generated by use of the knives 70 on a tray sealing machine 10, and that can also be heated in a closely controllable fashion. The knife 70 also includes a release coating 80 applied over the entire interior and exterior surface of the knife 70. The coating 80 is an electroless metal coating, such as an electroless nickel, copper, gold, palladium, cobalt, silver or tin coating that can be deposited on the surfaces of the knife 70 in any suitable or conventional manner for applying coating of this type, such as the manner disclosed in Henry et al. U.S. Pat. No. 4,830,889, which is incorporated herein by reference. The coating 80 provides a number of well-known advantageous properties to the knives 70, including uniformity over the coated item to a ±0.0001″/side thickness; excellent corrosion resistance; wear and abrasion resistance; non-magnetic and magnetic properties; solderability; high hardness; amphorous (microcrystalline) deposit; excellent adhesion; low coefficient of friction; high reflectivity; EM/RFI shielding; preplate for precious metal plating; heavy deposits; and deposits onto wide range of metallics and non-metallics.

Further, in addition to these beneficial properties provided by coatings of this type that are observed when the coatings are deposited on wear parts as discussed in the Henry et al. '889 patent, unexpectedly, the coating 80, when utilized on the knives 70, also functions as a highly effective release layer for the knives 70. This result is unexpected in that the knives 70 are heated to enable each knife 70 to more easily and quickly sever the lidding material 18 during operation of the sealing machine. The lidding material 18 is normally a plastic material, such as a polyethylene, that melts when contacted by the heated knives 70. Thus, the melted portions of the lidding material 18 in contact with the knives 70 previously became adhered to the knives 70, necessitating the cleaning of the knives 70 to remove this buildup of the material 18 on a very frequent basis. However, after applying the coating 80 to the knives 70, the coated knives 70 are heated and moved into contact with the lidding material film 18 to sever the film 18 around the tray 14, and the coating 80 prevents the lidding material 18 that has been melted or softened by contact with the knives 70 from adhering to the knives 70. Thus, because the material 18 does not adhere well to the knives 70, this prevents the cover formed by the material 18 from being malformed by the attachment of the material 18 forming the cover to the moving knives 70. Also, any lidding material 18 that does remain on the knives 70 is also easily removable from the knives 70 due to the release properties of the coating 80.

Alternatively, the coating 80 can be applied to the knives 70 in a manner that allows the coating 80 to become part of the knives 80 as opposed to a separate layer disposed on the exterior surfaces of the knives 70. In particular, the coating 80 can be formed on the knives 70 using a process that integrates the composition forming the coating 80 directly into the material forming the knives 70. Examples of coatings 80 of this type include Endura 100R-V and Endura 203X3-CR coatings, sold by Endura Coatings of Sterling Heights, Mich.

In the application of coatings 80 of this type, especially to knives 70 formed from aluminum, initially the surface of the knives 70 are converted from aluminum to aluminum oxide using an electrochemical process. In this process, the crystals of aluminum increase in size, thereby creating a porous matrix of ceramic. This matrix is then sealed over a predetermined period of time with an infusion of <1 micron-sized fluoropolymers that provide the surface of the aluminum material with a low friction property. The fluoropolymer particles are also stable at high temperatures, meaning the coating 80 formed utilizing the particles is able to be utilized on components that are employed in high temperature processes. Upon curing, the fluoropolymers cause the low friction property to remain on the surface of the knife 70, such that the knife 70 resists build up of any lidding material 18 thereon, and also enables any material 18 sticking to the knife 70 to be easily removed.

For knives 70 formed of materials other than aluminum, to apply the coating 80 the knife 70 initially has a metal, and preferably a nickel alloy plated onto the exterior surface of the knife 70 to form a porous layer on the exterior of the knife 70. The nickel alloy layer is subsequently sealed with the infusion of <1 micron-sized fluoropolymers that provide the surface of the knife 70 with a low friction property.

The particular fluoropolymers and/or duration are selected based on the material forming the knives 70 and the desired performance factors for the coating 80.

In addition to the knives 70, the coating 80 also can be utilized in a similarly beneficial manner on the other components of the tooling 30. For example, the knives 70 of the knife set 50 are disposed on the knife ring 40, best shown in FIGS. 2 and 4. The knife ring 40 is also formed of a metal, and preferably aluminum, and can have any shape that defines an open interior 41 conforming to the configuration of the tray 14 formed by or used in the particular tray-sealing machine. Preferably, the knife ring 40 is rectangular in shape with a peripheral rim 42 at one end and a ridge 44 spaced from the rim 42 to define a channel 46 therebetween. Each knife 70 of the knife set 50 is positioned against the rim 42 and held outwardly from the ring 40 by the ridge 44 to position the lower end 76 and serrations 78 of each knife 70 below the knife ring 40 such that the lower end 76 of each knife 70 properly contacts the lidding material film 18. Because the ridge 44 of the knife ring 40 is positioned adjacent the lower end 76 of each knife 70, the application of the coating 80 to the knife ring 40 also prevents any lidding material 18 softened or melted by the knives 70 from adhering to the knife ring 40. Also, the particular coating 80 applied to the knife ring 40 can be the same electroless metal coating used on the knives 70, or can be an electroless coating formed with a different metal applied in a similar or different process, or a coating 80 formed as a part of the material that comprises the knife ring 40.

In order to properly heat the knives 70 in order to soften and sever the film 18, the tooling 30 also includes a strip heater 60 best shown in FIGS. 1 and 6. The heater 60 includes a pair of leads 62 which extend outwardly from the heater 60 and through an aligned opening 64 in the knife ring 40 for connection to a power source (not shown) on the machine 10 to operate the heater 60. The heater 60 is positioned within the channel 46 on the knife ring 40 between the knife ring 40 and the knives 70 of the knife set 50 such that the heat generated by the heater 60 also heats the knife set 50 and knife ring 40.

Looking now at FIGS. 2 and 3, the clamp 90 is illustrated which is utilized in conjunction with the knives 70 to hold and seal the lidding material film 18 over the tray 14 while the knives 70 soften and sever the lidding material 18 around the periphery of the tray 14 to form the cover. The clamp 90 conforms to the shape defined by the interior of the knife ring 40 and is preferably rectangular in shape with dimensions slightly less than the interior dimensions of the knife ring 40 such that the clamp 90 can be positioned within the knife ring 40 without interfering with operation of the knives 70. The clamp 90 also preferably includes a member of bores 92 spaced from one another and extending through the clamp 90 between an upper end 94 and lower end 96. The clamp 90 can be formed of any suitable, rigid material, including aluminum, as such the clamp 90 can also be heated by the strip heater 60 or another heating member during operation of the tray-sealing machine to melt and seal the lidding material 18 to the tray 14 to form the cover. Because the primary function for the clamp 90 causes the clamp 90 to contact the film 18, and due to the proximity of the clamp 90 to the knife ring 40 during the process of severing and sealing the film 18 to the tray 14, preferably the clamp 90 also includes the exterior coating 80. The coating 80 on the clamp 90 can be formed of the same material as is applied to the knife ring 40 and knives 70 or can be a different electroless metal coating, or a coating 80 that is integrally formed with the material constituting the clamp 90. In either case, the coating 80 is deposited on the clamp 90 in a similar or identical process and functions identically to the coating 80 on the knife ring 40 and knives 70, thereby preventing the lidding material 18 forming the cover on the tray 14 from securely adhering to the clamp 90 such that the lidding material 18 falls away from the clamp 90 when the clamp 90 is moved away from the tray 14 by the machine, or so that any lidding material 18 that does remain attached to the clamp 90 is easily removed.

Further, while the above description has covered the preferred embodiments of the present invention, other alternatives are also possible. For example, the coating 80 can be selectively applied to only those portions of the tooling 30 that directly contacts the lidding material film 18, thereby reducing the amount on each tooling, as well as reducing the associated time and costs for applying the coating 80. Also, the coating 80 can be applied to tooling 30 that is not heated prior to severing the film 18 to prevent the film 18 from adhering to the tooling 30 under various non-heated conditions.

Various alternatives and other embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.

Claims

1. Tooling for use in severing lidding material to a tray, the tooling comprising; a) a heated sealing member adapted to seal the lidding material to the tray;b) a heated cutting member adapted to cut the lidding material around the tray; andc) a release coating deposited at least partially within both the sealing member and the cutting member to prevent the lidding material from adhering to the sealing member and the cutting member.

2. The tooling of claim 1 wherein the release coating is formed at least partially of at least one fluoropolymer.

3. The tooling of claim 2 wherein the at least one fluoropolymer comprises particles having a size of less than 1 micron.

4. The tooling of claim 3 wherein the at least one fluoropolymer consists of particles having a size of less than 1 micron.

5. The tooling of claim 1 wherein the cutting member comprises: a) a knife ring; andb) a knife set connected to the knife ring, wherein the release coating is deposited at least partially on the knife ring and the knife set.

6. The tooling of claim 5 wherein the knife set includes a pair of knives, each knife having a lower cutting edge.

7. The tooling of claim 5 further comprising a heating element disposed on the knife ring and capable of heating both the knife ring and knife set.

8. The tooling of claim 1 wherein the sealing member is mounted within the cutting member.

9. The tooling of claim 1 wherein the release coating is deposited at least partially within the sealing member.

10. The tooling of claim 8 wherein the sealing member is generally rectangular in shape.

11. The tooling of claim 9 wherein the cutting member is generally rectangular in shape.

12. The tooling of claim 1 wherein the release coating is formed at least partially of a nickel layer.

14. A cutting member for severing a thermoplastic web around an item, the cutting member comprising: a) a body having an upper end and a lower end, the lower end including a cutting surface; andb) a release coating integrally formed within the cutting surface.

15. The cutting member of claim 14 wherein the release coating is formed with submicron particles of at least one fluoropolymer.

16. The cutting member of claim 15 wherein the release coating is formed with a nickel alloy component.