Claims:We Claim,

1. A two platen injection molding machine with common casting for fixed and moving platen, comprising:

a mold clamping unit (11) to produce high quality molded articles by providing adequate clamping force, an injection unit (12) located at upstream end of said mold clamping unit (11) to provide required plastic melt materials for part to be molded, and a base unit (9) to provide rigid structure to the mold clamping unit (11) and the injection unit (12);

said the mold clamping unit (11) comprising a fixed platen machining part (1) fixed to the top of said base (9) and a moving platen machining part (2) slidably mounted on a plurality of tiebars (3) to mount a halves of the mold on each of said fixed platen (1) and said moving platen (2), said tiebars (3) extend from the rear of said moving platen (2) to compensate the tonnage/clamp force, at least one tonnage cylinder (4) located at the rear side of said fixed platen (1) to develop the tonnage/clamp force, an ejector assembly (8) located at downstream end of the mold clamping unit (11) to eject plastic article after cooling from the mold;

said the injection unit (12) comprising a barrel and screw assembly (5) to deliver said plastic melt materials where said barrel is located at rear side of said fixed platen (1) and said screw is rotatable inside the barrel and moves axially in a downstream direction by an injection part (7) to downstream end of said barrel to discharge the plastic melt materials via a nozzle (10), a thrust unit assembly to manipulate force generation, a hopper assembly (6) provided in the vicinity of the upstream end of said barrel and screw assembly (5) to convey raw plastic granules or powders, and an injection part (7) located behind said barrel and screw assembly (5) to inject said plastic melt material for part to be molded;

characterized in that said fixed platen (1) and said moving platen (2) having a casting of same geometry to generate equal deflection force on said fixed platen (1) and said moving platen (2) during tonnage to minimize or prevent flashes at parting line which leads to the increased mold life.

2. The two platen injection molding machine with common casting for fixed and moving platen as claimed in claim 1, wherein said fixed platen (1) and said moving platen (2) are manufactured by the sand casting technology.

3. The two platen injection molding machine with common casting for fixed and moving platen as claimed in claim 1, wherein the casting of said fixed platen (1) and said moving platen (2) are interchangeable.

Dated this on 11th day of December, 2018.
, Description:FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

1. TITLE OF THE INVENTION:
A Two Platen Injection Molding Machine with Common Casting for Fixed and Moving Platen

2. APPLICANT:
(a) NAME : Windsor Machines Limited
(b) NATIONALITY : Indian
(c) ADDRESS : Plot No. 6 & 7, GIDC Chhatral,
Kalol-382729,
Gujarat, India.

3. PREAMBLE TO THE DESCRIPTION
þ COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed.

Field of Invention:

The present invention relates to an injection molding machine and more particularly it relates to a two platen injection molding machine having common casting for both the platens i.e. fixed platen and moving platen.

Background of Invention:

The injection molding machines are generally used for producing plastic products by using injection molding process. The injection molding machine mainly consists two primary units i.e. injection unit and clamping unit. There are various types of injection molding machine are available in the market, for example, hydraulic, mechanical, electric, and pneumatic. The geometry of the machine can be either horizontal or vertical, but most of the machine has horizontal alignment. The vertical alignment can only be used in some application which requires taking advantage of gravity.

At present, the demand for injection molding machine with high efficiency is increases and the industry is growing at higher needs of the machine with durable machining parts and effective output. At present, most of these machines having two platens use different geometry for casting of each platen part. The casting is an individual part and serves as a raw material for machining part for both fixed platen and moving platen. The use of different geometry for casting of each platens lead to various limitations and disadvantages. However, all conventional injection molding machine having platens of two different casting elements made up from different geometry. Also, the platen design is asymmetric in nature and hence moving platen can not be used as fixed platen and fixed platen can not be used as moving platen which is one of the disadvantages of the conventional injection molding machine.

Various prior arts have been disclosed describing the injection molding machine parts. The prior art document US20040262813A1 describing about injection molding machine comprises movable platen to secure a mold half, fixed platen to secure another mold half. The movable platen is slidably mounted on multiple tie bars which extend from a backside of system to fixed platen. The another prior art document JP2004050477A describing about the mold thickness adjusting mechanism capable of adjusting a mold thickness with a simple structure comprising stationary platen to which a stationary mold is attached, a rear platen connected to the stationary platen via a plurality of tie bars, and a movable platen provided so as to be able to advance and retract along the tie bars by the mold clamping mechanism.

Moreover, the further prior art document CN108247953A describing about choice of gate type and position, the design of the pouring system, the selection of the parting surface and the injection molding part, the design of the clamping guide mechanism and the reset mechanism, and the demolding of the push rod. And, document US20170355119A1 describing about injection molding machine includes a mold clamping unit, a plasticizing unit, and a control section which controls operations of the units. The mold clamping unit includes a stationary platen which is fixed to the top of a base frame and to which a fixed mold is attached, a movable platen which moves in the lateral direction of the view on a slide member to which a movable mold is attached, and a plurality of tie bars which interlock the stationary platen and the movable platen with each other.

However, abovementioned conventional injection molding machines are complex in structure which having platens of different geometry and do not apparently describe about the manufacturing of platen parts, materials used for manufacturing platens parts, or symmetric nature of both the platens. Further, different geometries have dissimilar property in terms of flexibility, durability, straining, deformation etc. Hence, due to the two different geometry used for casting of both the platens, there are the cases of generation of dissimilar deflection patterns at fixed and moving halves of the mold during the injection process which results into flashes at parting line and poor dimensional consistency. Also, the dissimilar deflection pattern leads to the poor and inaccurate strength to weight ratio which affects the process outcomes.

The aforesaid conventional injection machines encounter various problems which lead into the difficulties like dissimilar deflection pattern, decreased mold life, requirement of two separate patterns for casting, huge capital investment, handling of more number of patterns in foundry, large space occupied for pattern storage, and high inventory cost due to separate casting.

Hence, it is desperately needed to introduce an injection molding machine that overcomes the shortcomings of abovementioned conventional injection molding machines by providing common casting for both the platens i.e. fixed platen and moving platen.

Object of Invention:

The main object of present invention is to provide a two platen injection molding machine having common casting for both the platens i.e. a fixed platen and a moving platen.

Another object of present invention is to provide a two platen injection molding machine which provides similar deflection pattern of fixed platen and moving platen while molding process.
Yet another object of present invention is to provide a two platen injection molding machine that minimizes or prevents the flashes at parting line to eliminate the end product defects and to provide vast impact on the overall outcomes.

Still another object of present invention is to provide a two platen injection molding machine with interchangeable fixed platen assembly and/or moving platen assembly.

The further object of present invention is to provide a two platen injection molding machine that is configured to reduce numbers of required patterns for casting and thus reduces capital investment for pattern manufacturing.

Yet, the further object of present invention is to provide a two platen injection molding machine that simplifies the supply chain management and standardizes the internal raw material logistics.

Summary of Invention:

The present invention discloses a two platen injection molding machine having common casting of fixed platen and moving platen and further comprising mold clamping unit which provides required tonnage for plastic part to be injected and molded, injection unit provides required plastic melt material for part to be injected and molded, and base unit facilitates the mounting and assembly of the whole said mold clamping unit and injection unit on the top of the base. The common casting of fixed platen and moving platen eliminates the dissimilar deflection pattern of both the platens due to similar geometry. The common casting of said fixed platen and moving platen eliminates the end product defects and provides vast impact on the overall outcomes.

The injection molding machine of present invention provides multifold benefits to industries and end users which are described in the following pages of specification.

Brief Description of Drawings:

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.

Figure 1 shows a schematic diagram of a two platen injection molding machine according to present invention.

Figure 2 shows a casting of the fixed platen and the moving platen of injection molding machine according to present invention.

Figure 3 shows a perspective view of generation of deflection pattern of fixed platen and moving platen during tonnage operation according to present invention.

Detailed Description of Invention:

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompany drawings. The invention is capable of other embodiment, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.

It is to be also understood that the term "comprises" and grammatical equivalents thereof are used herein to mean that other components, ingredients, steps, etc. are optionally present. For example, an article "comprising" (or "which comprises") components A, B, and C can consist of (i.e., contain only) components A, B, and C, or can contain not only components A, B, and C but also contain one or more other components.

Now, referring to Fig. 1, according to exemplary embodiment of the present invention, the injection molding machine comprising a mold clamping unit (11) to produce high quality molded articles by providing adequate clamping force, an injection unit (12) located at upstream end of said mold clamping unit (11) to provide required plastic melt materials for part to be injected and molded, and a base unit (9) to provide rigid structure and mounting of the said mold clamping unit (11) and said injection unit (12).
It is to be noted that in given exemplary embodiment, a two platen injection molding machine comprising various elements, where the location of said elements are segregated as per abovementioned three major section of the injection molding machine as shown in Fig. 1 i.e. said mold clamping unit (11), said injection unit (12) and said base unit (9). The alignment of injection molding machine of present invention is horizontal. This is the normal alignment of said machine in all industries. However, it is also aligned vertically in applications like insert molding which requires gravity to accomplish molding operation.

Referring continuous with Fig. 1, the mold clamping unit (11) comprising of sub-assemblies like a fixed platen machining part (1) to mount a half of the mold and fixed to the top of the base (9), a moving platen machining part (2) to mount another half of the mold which is slidably mounted on a plurality of tiebars (3) which extend from the rear of said moving platen (2) which interlocks the fixed platen (1) and moving platen (2) with each other to compensate a tonnage/clamp force, at least one tonnage cylinder (4) located at the rear side of said fixed platen (1) to develop the said tonnage/clamp force, an ejector assembly (8) located at downstream end of said mold clamping unit (11) to eject plastic article after cooling from the said mold.

The injection unit (12) comprising of sub-assemblies like a barrel and screw assembly (5) to deliver said plastic melt materials where said barrel is located at rear side of said fixed platen (1) and said screw is rotatable inside the barrel and moves axially in a downstream direction by an injection part (7) to downstream end of said barrel to discharge the plastic melt materials via a nozzle (10), a thrust unit assembly (not shown) to manipulate force generation, a hopper assembly (6) provided in the vicinity of the upstream end of said barrel and screw assembly (5) to convey raw plastic granules or powders, and said injection part (7) located behind said barrel and screw assembly (5) to inject said plastic melt materials for part to be molded. The whole mold clamping unit (11) and the injection unit (12) are mounted on the base unit (9). Said base (9) provides rigid structure to the mold clamping unit (11) and the injection unit (12) of the injection molding machine of the present invention.

The injection molding machine as shown in Fig. 1 according to one embodiment of the present invention is particularly adapted to have the fixed platen (1) and the moving platen (2), which are used to mount a halves of the mold of a part to be produced on each of said fixed platen (1) and said moving platen (2). According to Fig. 1, said the mold is made into two halves, wherein one half is mounted on the said fixed platen (1) and another half is mounted on the said moving platen (2). The fixed paten (1) remains stationary during clamping operation of the cycle. Whereby, the moving platen (2) travels in an axial direction through the tiebars (3) to close the two halves of the mold and also provide different mold height adjustment. The four tiebars (3) compensating the tonnage/clamp force developed by the tonnage cylinders (4) by stretching in a direction to its length. The required plastic melt material is delivered by the barrel and screw assembly (5). Said the screw has spiral flights on its diameter that facilitates conveying of the raw plastic granules or powders coming from the hopper assembly (6), which stores raw plastic material to the mold through the nozzle (10) at its end.

Fig. 2 shows the casting of said fixed platen (1) and said moving platen (2) which is symmetrical and identical in nature. The shape and geometry of the said casting is also apparent from the Fig. 2. Said the shape and geometry remains similar with the different tonnages of the machine which enables easy modeling of the new machine development, pattern making for the casting and reduces new product development cycle. The material used for construction is preferably, but not limited to Spheroidal Graphite Cast Iron (SG450/10).

Fig. 3 depicts the deflection behavior of the said fixed platen (1) and the moving platen (2) while tonnage operation. From the Fig. 3, it can be seen that by having common casting, the deflection in both negative and positive directions is controlled with effective strength to weight ratio which was not achieved in conventional injection molding having different castings for fixed and moving platen.

The fixed platen (1) and moving platen (2) having a common casting as shown in Fig. 2 produced using the same geometry by the said sand casting technology. The sub-assemblies of said fixed platen (1) and said moving platen (2) having various structural geometries like faces, vertices, edges and tapings. These structural geometries of both the platens i.e. fixed platen (1) and moving platen (2) are similar in nature and hence casting can be interchanged for said fixed platen (1) assembly and/or said moving platen (2) assembly in case of requirement for shop floor assembly department or for order of platens for service department against customer demand.

Now, referring to Fig. 3 in combination with Fig.1 and Fig.2, during molding operation, when said moving platen (2) travels in an axial direction of the said machine to close the two halves of the mold, the tonnage/clamp force is developed by said tonnage cylinders (4) by stretching in a direction to its length. Due to the generation of aforesaid clamping force, the deflection is occurs in both the platens and also in both the mold halves when comes in contact with each other while closing two halves of the said mold. The deflection pattern generated during abovementioned process is similar and identical for said fixed platen (1) and said moving platen (2) as shown in Fig. 2. The similar and identical nature of deflection pattern is only become possible due to aforesaid common casting of fixed platen (1) and moving platen (2). Also, in case of common geometry, due to common casting the deflection pattern on both mold halves are equal which helps to minimize or prevent flash at parting line which leads to the increased mold life. The deflection behavior of both the platens i.e. fixed platen (1) and moving platen (2) is in different direction during tonnage operation as shown in Fig. 3, to control the deflection in positive direction and negative direction with good strength to weight ratio.

The size of the casting of said fixed platen (1) and said moving platen (2) depends on the design of the injection molding machine. Basically, the size of the said casting is derived from the distance between said tiebars (3) in horizontal and vertical directions. The distance between said tiebars (3) is decided with respect to the mold sizes of part to be produced that defines the clamping tonnage requirement of the machine. So the size of the casting platens varies according to tonnage of the machine.

The injection molding machine of the present invention is apparently advantageous over existing machine. Said the machine with simplified design provides reduced numbers of required patterns for casting and thus reduces capital investment for pattern manufacturing, inventory reduction, simplified supply chain management, easy and standardized internal raw material logistics, reduced pattern storage space requirements, improved casting quality and soundness, elimination of demand of various molding setup, flexible manufacturing due to repetitive orders of common casting, standardization of mold boxes, and automation in casting manufacturing process.

The invention has been explained in relation to specific embodiment. It is inferred that the foregoing description is only illustrative of the present invention and it is not intended that the invention be limited or restrictive thereto. Many other specific embodiments of the present invention will be apparent to one skilled in the art from the foregoing disclosure. All substitution, alterations and modification of the present invention which come within the scope of the following claims are to which the present invention is readily susceptible without departing from the spirit of the invention. The scope of the invention should therefore be determined not with reference to the above description but should be determined with reference to appended claims along with full scope of equivalents to which such claims are entitled.

List of Reference Numerals

1. Fixed Platen
2. Moving Platen
3. Tiebars
4. Tonnage Cylinders
5. Barrel and Screw Assembly
6. Hopper Assembly
7. Injection Part
8. Ejector Assembly
9. Base Unit
10. Nozzle
11. Mold Clamping Unit
12. Injection Unit