JPH0615727A - Production of thermoformed plastic product - Google Patents

Abstract

PURPOSE: To reduce cost and to enhance efficiency by forming a plastic preform and molding the same in a perfect plastic receptacle produced from a predetermined amt. of a material without generating scrap. CONSTITUTION: The plastic sheet supplied to an extruder 3 is cut into a precut plastic form 1 or a preform by an on-line press 2. In this case, formed scrap is again introduced into the extruder 3 from a grinding machine 5 by a pneumatic conveyor 5'. Thereafter, the scrap can be transported to remote positions 12, 12 by a truck 10. The precut form 1 is heated therein by a heater 6 and a product 14 is produced by a mold 7 and a counter mold 8. Therefore, it is unnecessary to place a thermoforming machine at the same position 11 as the extruder and an eccentric press and the transport cost of a precut disc becomes extremely low. The product is thermoformed at a position near to a market and the distribution thereof is accelerated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing thermoformed plastic products. More particularly, the present invention relates to manufacturing methods that streamline the manufacture of thermoformed plastic receptacle products.

[0002]

2. Description of the Prior Art In known methods, ground or powdered plastic resin is fed to an extruder where a plastic sheet is produced. The extruded plastic sheet is used as a raw material for a product forming machine. After exiting the extruder, the plastic sheet is typically returned to a cooling calendar and winder. One feature common to the known methods is that the plastic sheet is produced by an extruder for the thermoforming process.

Known thermoforming methods involve heating a sheet of thermoplastic material to a thermoforming temperature and causing deformation of the sheet and applying air pressure or vacuum which takes the shape of a mold. The mold is then air or water cooled. After cooling below the thermoforming temperature, the molded article retains its newly formed shape and can be removed from the mold.

For products such as glasses or margarine shakers, counter molding may be used. This counter-molding helps achieve a more uniform part thickness. Finally, each known method requires a thermoforming machine to be equipped with a cutting device for removing scrap material from the product formed at the end of the manufacturing process.

In addition to the known methods mentioned above, there is the so-called "English machine", which is a combination of an injector and a thermoforming machine. With regard to the "English machine", heating of the comminuted resin, injection of the preform and molding of the product all occur on one machine.
However, this machine is very expensive for purchase and gives a relatively low production rate,
There was no success in the market.

With regard to revolutionize the production of a product summary consumer invention, after studies and innumerable, the present inventors have found the invention of a new process for the preparation of thermoformed plastic products.
This method requires the use of preforms such as precut plastic discs or other shapes as raw materials for the production of glass and pots, and likewise.
The use of other pre-cut plastic shapes for trays and other products is required. These preforms are
It is manufactured by a press, for example an eccentric press, and placed on a line with an extruder and a calender. 1 of the present invention
One purpose is to provide a manufacturing method that can reduce the cost of thermoforming machines. Another object of the present invention is to provide a manufacturing method that streamlines the manufacture of thermoformed plastic receptacle products to minimize manufacturing costs.

Specific Description of the Invention As shown, the process of the present invention is a raw or powdered plastic resin for the production of glasses, pots, trays and other receptacle products. Provide a way. This plastic resin is fed to the extruder 3 which produces a continuous plastic sheet. This plastic sheet is cooled by being passed through a calendar before being fed to an on-line press 2, for example an eccentric press, in which a continuous plastic sheet has a pre-cut plastic shape with a predetermined size and shape. 1 or cut into preforms. Since these precut shapes 1 are raw materials for the production of glasses, pots, trays and other receptacle products, they can take discs or other precut shapes depending on the shape of the product to be formed. . If the press 2 cuts the pre-cut plastic form 1 from a plastic sheet, the excess material or "scrap" produced by the press 2 is easily transported to the grinding machine 5 and is designated by 5 '. Is reintroduced into the extruder 3.

After a large number of precut shapes 1 have been produced, they can be transported by truck 10 to one or more remote locations, for example "12,12 '", for operation by a thermoforming machine. As would be the case, scrap is not produced on thermoforming machines, so these thermoforming machines do not have to put them in the same position 11 as the extruder and eccentric press. The cost of transporting the pre-cut discs is very cheap compared to the cost of doing so, which can provide additional savings. It can be thermoformed very close to the ground, thus facilitating product distribution and reducing associated shipping costs.

The thermoforming operation of the present invention involves heating the precut mold 1 with a heater 6. After exiting the heater, the individual precut shapes 1 are introduced into the mold 7. The mold 7 can be air or water cooled. Counter mold 8
Can be used in connection with the mold 7 to provide an even thickness of the formed product.

Preform 1 as produced by press 2 is a complete and well-formed product 14 from molds 7 and 8 without any excess material or scrap.
It is to be understood that the volume, size and shape as required to supply the appropriate amount of material for manufacturing the is predetermined. Therefore, the glass, pot, tray or other plastic receptacle product 14 that is formed is taken directly from the mold 7 and dispensed by the truck 16 without additional manufacturing steps such as trimming scrap from the product. obtain.

The method of the present invention achieves the objective of reducing the overall cost of a thermoforming machine, wherein said method heats a cutting device to remove scrap material from the glass, pot, etc. being produced. No need for molding machines. This advantage is of utmost importance when the product produced is composed of polypropylene whose cutting operation is critical.

When cylindrical products, such as pots and plastic glass, are manufactured using conventional methods, the plastic sheets supplied as raw materials for thermoforming machines
40% will be scrap. Therefore, with the conventional method, it is necessary to heat all of the plastic sheets fed to the thermoforming machine to their forming temperature. This involves heating 40% of the material that will eventually be scrapped. With the method of the present invention, the pre-cut form is simply heated and the heating energy associated with heating scrap is saved. This savings is important when the scrap rate is as high as 40%.

Using conventional methods, scrap should be produced on a thermoforming machine and manually removed from the machine, placed in a grinder and reintroduced into the extruder. This needs to be compared with the manufacturing process of the invention, where the scrap is guided in an extruder / press combination and fed directly to the grinder, and the milled scrap is fed to the extruder. This transportation can be done by an automatic pneumatic conveyor.

In addition, extruder production rates are typically
Significantly faster than the production rate of thermoforming machines, one extrusion line can supply several thermoforming machines. For example, in a conventional extrusion manufacturing facility, about 40 kg of plastic scrap for each 100 kg of disposable coffee glass having a diameter of 50 mm produced would be produced in a thermoforming mold. Since this scrap should be crushed and returned to the extruder, the individual thermoforming machines should be located close to the extruder. If the thermoforming machine and extruder are located at different locations, the costs associated with shipping the scrap would be high.

Furthermore, since the final glass is generally distributed in several markets, it is worthwhile to locate the thermoforming molding machine close to those individual markets. As illustrated, the weight of 1 m ³ of coffee is 165
Consider that it is about kg. Transportation costs, since tracks 22m ³ can transport their glass only 3630Kg, made Hijoni higher. In contrast, using the method of the present invention, 1 m ³ of coffee glass of a 50 mm disc weighs 785 kg. A 22 m ³ truck can carry 17270 kg of these discs, or 4.75 times the number of glasses. Therefore,
Using the method of the present invention, the manufacturing system can have a centrally located extrusion center for manufacturing the discs, and thermoforming can be done at locations close to some markets. Therefore, the freight for transporting the product can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram of the manufacturing method of the present invention.

[Explanation of symbols]

 1 ... Pre-cut plastic type 2 ... Press 3 ... Extruder 4 ... Calendar 5 ... Grinder 6 ... Heater 7 ... Mold 8 ... Counter mold

Claims (8)

[Claims] 1. A method of manufacturing a plastic product, comprising:
Forming at least one plastic preform manufactured from a predetermined amount of material; and shaping the preform into a scrap-free preform into a complete plastic receptacle manufactured from only the predetermined amount of material A method comprising the steps of: 2. A method of making a thermoformed plastic product comprising: extruding a plastic strip; cutting the plastic strip into a number of precut shapes having a predetermined shape; heating each precut shape to a thermoforming temperature. And forming the individual heated precut shapes into the desired product. 3. The plastic strip cutting produces scrap material, and the method processes the scrap material and conveys the processed scrap material to an extruder for additional extrusion of the plastic strip. The method of claim 2 including the following. 4. The pre-cut to a constant volume wherein the desired product comprises a predetermined amount of plastic material and the cutting has the predetermined amount of material to cause the molding without scrap. The method of claim 2, wherein the shape is cut. 5. A method of making a thermoformed plastic product, comprising: extruding a plastic strip; cutting the plastic strip into a number of precut shapes having a predetermined shape; A method comprising: transporting to a molding location; heating the individual transported precut shapes to a thermoforming temperature; and shaping the individual heated precut shapes to a desired product shape. 6. A method of making a thermoformed plastic article, comprising: extruding a plastic sheet at a first location; for shaping the plastic sheet at the first location to make a plastic receptacle article scrap-free. Cutting into at least one pre-cut shape having a predetermined size and shape; transporting said at least one pre-cut shape to a second location remote from said first location; said at least one transported Heating the precut form to a thermoforming temperature; and shaping the at least one heated precut into a desired product. 7. The method of claim 6 wherein said cutting produces a number of said precut shapes and said transporting a number of said precut shapes to each of a number of second remote locations. 8. The extrusion is performed by an extruder, the cutting of the plastic strip produces scrap material, and the method grinds the scrap material,
And including conveying the crushed scrap material to the extruder for additional extrusion of the plastic sheet, and cutting the plastic sheet, each forming the desired product to be complete and scrap-free. 8. A method as claimed in claim 7, wherein the individual precut shapes are cut into the same amount of plastics material if required to do so.