CA2155097A1

CA2155097A1 - Injection moulding machine

Info

Publication number: CA2155097A1
Application number: CA002155097A
Authority: CA
Inventors: Bruno Svoboda
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-02-01
Filing date: 1994-02-01
Publication date: 1994-08-18
Also published as: EP0681520A1; KR960700141A; AU5875794A; DE59401209D1; CZ196795A3; ES2097636T3; BR9406555A; ATE145852T1; WO1994017977A1; EP0681520B1

Abstract

Injection moulding machine with a machine frame (2, 3, 13) and a fixed and hydraulically or electromechanically movable die platen (5). In order to compensate to a large extent for the bending moment arising during closure of the mould, which distorts the machine frame (2, 3, 13), the machine has, in addition to an actuatable force member (9) that operates the die platen, preferably a hydraulic jack, a further drivable power member (10) whose force is applied symmetrically to that of the first, and which is simultaneously actuated by a force that corresponds to or is proportional to the closing force produced by the first power element (9).

Description

~ I 5 5 0 9 7 FILE, ~ tN ri i. ~ J5-_ Injection Moulding Machine The present invention relates to an injection-moulding machine with a double C-shaped machine frame and a fixed as well as a hydraulically or electro- mechanically movable die platten, at least one additional force element being provided in an arrangement that is symmetrical with respect to force in order to balance out the bending moment that deforms the machine frame and is generated when the mould is closed, this preferably being a hydraulic ram that is acted upon by a force that corresponds to or is proportional to the closing force that is exerted exerted by the first force element.

Such injection moulding machines are generally known. The die plattens of these known machines are connected to each other by beams so as to absorb the axial forces that occur during the injection process, the movable mould carrier optionally being supported so as to the movable on these beams.

DE-AS-llO9 356 describes an injection moulding machine with a multi-part frame that incorporates two solid cast transverse members that are connected to each other by a plurality of longitudinal beams that extend in the mould-closing direction;
these beams serve to absorb the mould-closing forces. The longitudinal beams are arranged in a middle area of the transverse members, whereas beyond this middle area, on one side there is a fixed die platten as well as a die platten that can be moved by a first force element; on the other side there is an additional hydraulically powered force element that is arranged so as to be symmetrical with respect to force; this is used to balance out the bending moments that are exerted on the longitudinal beams by the first force element.

In addition, DE-Al-25 28 153 describes a single-column press with an upper and a lower frame that are in the form of arms that are secured to a vertical column-type frame, and between which there are a fixed die platten and also a die platten that can be moved by a first force element. In order to ~155097 compensate for the bending moments that deform the multi-part frames, an additional element is provided in an arrangement that is symmetrical with respect to power and which can be acted upon simultaneously with the first force element.

DE-Ul-92 12 480 describes an injection moulding machine with a single-part frame that supports a fixed die platten and a die platten that can be moved by a force element, this being supported--so as to be able to rotate--transversely to the axial direction of the force that is applied. The tipping ability of the die plattens that is achieved thereby ensures that these are always parallel, even in the face of great closing force.

JP 57209799 (Patents Abstracts of Japan, Volume 7, No. 68) describes a shaping machine in which the two transverse arms are connected through screw connections to the ends of a longitudinal arm, there being a mould-closing device and a compensating ram between the transverse arms, these being arranged so as to be symmetrical with respect to force in reference to the longitudinal arm, so that the turning moments exerted by the two rams balance each other out.

It is the task of the present invention to create an injection moulding machine of the type described in the introduction hereto, in which the parallelity of the die plattens is ensured during the mould-closing procedure.

A further task of the present invention is to prevent any bending of the double C-longitudinal arm in double C-shaped machine frames.

The present invention solves this problem in that the longitudinal arm of the double C-shaped machine frame is formed in one piece with the transverse arms thereof.

21~0~

As a result of this configuration, it is possible to eliminate the beams that usually absorb the axial forces; because of the arrangement of additional force elements, in particular on the hydraulic rams that act on the frame, the sum of the forces and bending moments acting on the frames can be reduced to zero and the frame can be kept free of distortion. In a particular, this is so because the bending moments generated by the closing force, in particular in the longitudinal direction of the frame, can be balanced out, at least by the force that counter-balances the closing force.

According to a development of the present invention, all the hydraulic rams are arranged on the machine frame and have axes that preferably run parallel to each other, which means that despite a readily accessible form closing unit, a distortion-free machine frame is guaranteed.

According to a further development of the present invention, the hydraulic rams are arranged on the inside of the arm in particular the longitudinal arm of the double C-shaped frame, and they operate in the same direction.

In another embodiment, the hydraulic rams that move the die plattens and the additional hydraulic rams work in different directions.

In another development of the present invention all the hydraulic rams can be connected to a common feed system, or else be supplied from different feed systems.

According to the present invention it is also possible to develop the injection moulding machine such that the fixed die platten is connected to a an additional platten that is arranged on the opposite arm; and such that the two plattens are articulated in each instance onto the particular corresponding arm.

215~097 According to another development of the present invention, provision can also be made such that the hinges lie in the axial direction of the hydraulic ram that operates the movable platten; and such that the two plattens that are hinged to each other are connected by way of an additional beam, this then serving as a guide for the movable die platten.

In a preferred embodiment, the injection moulding machine is characterized especially in that the two plattens that are hinged together, the additional beam, the movable die platten, and the hydraulic ram that operates this form a connected and coherent closing frame.

The present invention will be described below on the basis of the drawings appended hereto. Figures 1 to 8 show different embodiments of the injection moulding machine according to the present invention, identical parts bearing the same reference numbers in each case.
Figure 1 shows an embodiment with a double C-shaped frame, two arms 2, 3 being arranged on a pedestal 1, the arm 2 accommodating the fixed die platten 4 and the other arm 3 accommodating the mobile die platten 5. The pedestal 1 also supports an injection unit that delivers the moulding material. The die plattens 4, 5 support the mould halves 8, 8a.

The movable die platten 5 is connected to a hydraulic ram 9 that functions as a closing mechanism and this moves the die platten and generates the required press force; this is arranged on one side of the beam 13, i.e., the double C-longitudinal arm, and is parallel to this. In addition, another hydraulic ram 10 is fitted between the two arms 2, 3, and this is arranged on the other side of the beam 13, and is similarly parallel to this. The hydraulic rams 9, 10 are supplied from a common hydraulic line 6, and act in opposite directions.

215~097 -Thus, the arrangement of the additional hydraulic ram 10 is symmetrical with respect to force, so that the moment that is generated when the hydraulic ram 9 is working is balanced out,and these sum of all the moments is zero.

In order to fulfill the equation to the effect that the sum of all the forces and moments acting in the machine frame is equal to zero, according to the present invention, in this system, if the axial Z 1, Z 2 are unequally spaced away from the mid-line axis m, the piston surface of the rams 9, 10 must be made unequally large or an element that reduces the pressure must be incorporated in one ram line, or one of the two rams must be supplied from a dedicated and independent pressure supply system. In any case, what is achieved is that pure tensile forces are effective in the beam 13, and this is not loaded with moments; this is achieved by matching the force that is exerted by,the ram 10 to the closing force that is generated by the ram 9.

The arm 2 is secured rigidly to the pedestal 1, in contrast to which the arm 3 is connected to the pedestal by way of a groove-pin combination 12 so as to be axially movable, if necessary in order to prevent rotation of the beam 13. It is preferred that the groove be in the form of an elongated hole.

Figure 2 shows a modification of the embodiment shown in figure 1; in this, the arms 2, 3 are articulated onto the beam 13. The two hydraulic rams 9, 10 are arranged on both sides of the beam 13, on the inner side of the arm 3, the beam passing through the die platten 5, said beam serving as a guide element for the movable die platten 5.

A further embodiment is shown in Figure 3; in this, the frame 2 is configured as a one-piece C-shaped frame. The two hydraulic rams lie parallel to each other and parallel to the C-long arm, although they are supplied from different pressure pumps, not shown herein.

21 ~509 7 As is shown in Figure 4, it is also possible to arrange the hydraulic rams 9, 10 so that they oppose each other, when the additional hydraulic ram 10 that is used to equal out the bending moment is arranged on the outer side of the arm 2, and the bale 14 passes through both arms 2, 3 or else encloses them; this then clamps the parts together.

Figure 5 shows an embodiment in which the two arms 2, 3 are connected to a beam 13 that is articulated onto them, as is shown in Figure 2. However, each of the two arms is separated from the pedestal 1 by an additional hydraulic ram 10', 10", the direction of their axes being perpendicular to that of the hydraulic ram 9 that activates the movable die platten 5.
This configuration, too, guarantees that only tensile forces act on the beam 13, and also ensures that the die plattens 4 and 5 are parallel, since the sum of all the moments and forces can be held to zero by simply counterbalancing the forces of the hydraulic rams 10', 10".

Figure 6 shows an arrangement of the injection moulding machine that corresponds to the one shown in Figure 1, this being a vertical arrangement.

Figure 7 shows an injection moulding machine in which the movable die platten 5 is not activated directly by the hydraulic ram 9, but is arranged on the movable arm 3. The hydraulic ram 9 is located on the outer side of the arm 3 and the piston rod is secured to the inside of the arm 2. It moves the arm 3 against the additional hydraulic ram 10. The movable die platten 5 is thus moved indirectly by way of the arm 3, which slides on the pedestal 1. In this arrangement, the hydraulic rams 9, 10 are supplied separately. This version requires no additional beam 13.
In the embodiment that is shown in Figure 8, the beam 13 passes through the arm 3 and is secured rigidly to the inner side of the arm 2. A locking device 14 is arranged on the 2iS5097 outer side of the arm 3. The mould is closed by the ram 10 and then the beam 13 is locked automatically by the locking device 14. Then the two rams 9 , 10, which are arranged in parallel, build up the closing pressure.

Naturally, the embodiments described above can be used not only for injection moulding machines, but, essentially, for presses that are used to shape different materials.

A further embodiment is shown in Figure 9. In this version, in addition to the fixed die platten 4, there is an additional platten 17, each of these plattens being connected to the corresponding arm 2, 3 through hinged 16 that are on the axis of the hydraulic ram 9 and thus on the effective axis of the closing force F1. The fixed plattens 4, 17 are both connected by way of an additional beam 15. The die platten 5 that is moved by the hydraulic ram 9 slides along the additional beam 15 and uses this as a guide.

This configuration decouples the closing frame formed by the plattens 4, 5, 17, the additional beam 14, and the hydraulic ram 9, from the frame, and this ensures a further improvement in ensuring that the die plattens are parallel, particularly when the mould is being closed, even if the arms do spread apart slightly.

Even though the present invention has been described above on the basis of embodiments in which a hydraulic cylinder-piston assembly 10 was used to apply the counter-force, the present invention is not restricted thereto. What is important is the fact that this involves a powered force element that can be activated simultaneously with the closing ram 9, with a force that is equal to or proportional to the closing pressure.
Thus, the force element can be configured, for example, as an electrically powered ballscrew or threaded spindle.

Claims

NEW PATENT CLAIMS

1. An injection-moulding machine with a double C-shaped machine frame (2, 3, 13) and a fixed as well as a hydraulically or electro- mechanically movable die platten (5), at least one additional force element (10) being provided in an arrangement that is symmetrical with respect to force in order to balance out the bending moment that deforms the machine frame (2, 3, 13) and is generated when the mould is closed, this preferably being a hydraulic ram that is acted upon by a force that corresponds to or is proportional to the closing force that is exerted exerted by the first force element (9), characterized in that the longitudinal arm (13) of the double C-shaped machine frame (2, 3, 13) is formed in one piece with the transverse members thereof.

2. An injection moulding machine as defined in claim 1, characterized in that at least one additional powered force element (10) is an hydraulic ram that acts on the frame.

3. An injection moulding machine as defined in claims 1 and 2, characterized in that the hydraulic rams (9, 10, 10', 10") are arranged on the machine frame.

4. An injection moulding machine as defined in claim 1, characterized in that all of the hydraulic rams (9, 10) have axes that are parallel.

5. An injection moulding machine as defined in claims 1 and 2, characterized in that the hydraulic rams are arranged on the inner side of an arm (3) of the double C-shaped frame and operate in the same direction.

6. An injection moulding machine as defined in claim 3, characterized in that the hydraulic ram that actuates the movable die platten and the additional hydraulic ram work in different directions.

7. An injection moulding machine as defined in one of the preceding claims, characterized in that all of the hydraulic rams are supplied from a common feed system.

8. An injection moulding machine as defined in one of the preceding claims, characterized in that the hydraulic rams are supplied from different feed systems.

9. An injection moulding machine as defined in one of the preceding claims, characterized in that fixed die platten is connected to an additional platten (17) that is arranged on an opposite arm; and in that the two plattens are articulated onto the corresponding arm (2 ,3) (Figure 9).

10. An injection moulding machine as defined in claim 9, characterized in that the hinges (16) lie in the axial direction of the hydraulic ram that actuates the movable platten.

11. An injection moulding machine as defined in claims 9 and 10, characterized in that the two plattens that are connected to the arms through hinges are connected to each other through an additional beam (15); and in that the additional beam serves as a guide for the movable die platten.

12. An injection moulding machine as defined in claims 9 to 11, characterized in that the two plattens (4, 17) that are connected to the arms through hinges, the additional beam (15), the movable die platten (5) and the hydraulic ram (9) that actuates them form a connected closing frame.