EP0846049A2

EP0846049A2 - Injection-moulding unit for a machine for the injection moulding of plastics

Info

Publication number: EP0846049A2
Application number: EP96932445A
Authority: EP
Inventors: Karl Hehl
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-08-25
Filing date: 1996-08-13
Publication date: 1998-06-10
Also published as: CA2227992A1; WO1997007959A2; WO1997007959A3; JPH11511084A

Abstract

Described is an injection-moulding unit including a plastification unit (17) and a support block (10') designed to detachably hold the plastification unit. Also included is at least one spindle drive (A) with a spindle (31') and nut (78) to bring the nozzle (D) up against the mould (M). The longer section of the spindle (31') or nut (78) is rigidly blocked in rotation in relation to the stationary mould holder (35) and is designed to guide at least the support block (10') along a guiding zone (31a'), which zone is a portion of said longer section of the spindle or nut.

Description

Injection molding unit for a plastic injection molding machine

description

Regarding related applications

The invention claims the priority of applications 195 31 328, filed on August 25, 1995 and 195 42 453, filed on November 14, 1995, the disclosure content of which is hereby expressly made the subject of the present invention.

Technical field

The invention relates to an injection molding unit for a plastic injection molding machine for processing plastifiable masses according to the preamble of claim 1.

State of the art

Such an injection molding unit is known from EP-A 576 925 in which a carrier block is axially displaceably mounted relative to a stationary mold carrier. The connection between the carrier block and the stationary mold carrier takes place via nested electromechanical spindle drives, which comprise a drive unit designed as a hollow shaft motor for applying the nozzle to the injection mold and an injection unit that generates the axial movement of the screw conveyor within the plasticizing cylinder during injection. A rotary motor for rotating the screw conveyor is also provided on an injection bridge. As the only guide, which is not symmetrical to the spray axis, guide rails are provided on the machine base, on which at least the carrier block is guided. When the spindle nut of the hollow shaft motor rests on the spindle, which is non-rotatably connected to the stationary mold carrier, there is of course no problem

REPLACEMENT BLAπ (RULE 26) exact guidance. No other guide elements are provided. The serial arrangement of the drive unit and injection unit leads to a large overall length of the injection molding unit, since the movement paths of the two units line up. If a unit is defective, at least one 'spar' must be dismantled with both units, so that unnecessary extra work and additional costs result.

From DE-C 43 17 998 it is also known to arrange a drive unit for applying the nozzle and an injection unit each symmetrically to the spray axis. Electric motors serve as drives, which drive hollow shafts of the drive unit and injection unit via belt drives, which are nested inside one another. Here, too, both units can only be replaced together and separate guide elements, apart from the guide strips which are loosely placed on the machine base, are not provided.

From DE-C 41 30 287 the extension of a conventional plasticizing cylinder by insert pieces is known. This allows the length / diameter ratio (L / D ratio) of the conveyor to be changed. This is necessary when the performance of the injection molding machine has to be increased, e.g. to supply the plasticized mass with an increased thermal output.

Summary of the invention

Proceeding from this prior art, the present invention is based on the object of developing an injection molding unit of the type mentioned at the outset in such a way that improved guidance of the injection molding unit results in a favorable manner.

This object is achieved by an injection molding unit with the features of claim 1.

The only point connected to the stationary mold carrier and thus stationary at least in the direction of the spray axis, namely the point The point of articulation of the longer part of the spindle and spindle nut is used for a guiding function in that the longer part is also designed as a guide bar in its end region. Compared to the 'mere ^* guiding of the carrier block on the spindles of the spindle drives, this has the advantage of a considerably more precise and precise positioning.

Brief description of the figures

1 is a partially sectioned side view of an injection molding unit resting on the stationary mold carrier,

2 shows a view of the injection molding machine according to FIG. 1 from the right,

3 shows a section along line 3-3 of FIG. 1,

4 shows a side view of the injection molding unit according to FIG. 1 in a further embodiment, the guide area being supported by a support element,

5 shows a view of the injection molding unit according to FIG. 4 from the right,

6 shows a view of the injection molding unit according to FIG. 4 with a rotary motor that is identical in construction to the injection motors,

Fig. 7 shows a section through a hollow shaft motor.

Detailed description of preferred embodiments

The invention will now be explained in more detail by way of example with reference to the accompanying drawings. However, the exemplary embodiments are only examples that are not intended to limit the inventive concept to a specific physical arrangement.

The injection molding unit is used for dosing and injecting plasticized material such as plastics, in powder form Masses and ceramic masses in a mold cavity 80 of a mold M, which can be attached in part to a stationary mold carrier 35 of a mold clamping unit. With a nozzle D, the injection molding unit lies against the mold M during injection. Figures 1 to 3 show the basic structure of the Spritzgieß¬ unit of a plastic injection molding machine, as it is also the basis of the other embodiments.

The injection molding unit has a carrier block 10 ', by means of which the injection molding unit is essentially supported on a machine frame 81. The support takes place with the interposition of two strips 62 'which carry guide rails 19 on their upper side. On the guide rails, the carrier block 10 'on guide shoes 79 can be moved towards and away from the stationary mold carrier 35 by at least one spindle drive A. Nevertheless, the entire injection molding unit and its support are detached from the machine base, e.g. can be moved or pivoted as a structural unit for injection into the parting plane. A spindle 31 'as a longer part and a spindle nut 78 as a shorter part of the spindle drives A can be moved relative to one another, the spindle nut being rotatably connected to the axially displaceable carrier block 10' and the spindle 31 'to the stationary mold carrier 35. At least one hollow shaft motor 73 drives the spindle nut 78 of the spindle drive A to place the nozzle D on the mold M, if necessary via an integrated planetary gear.

Both spindle drives can be controlled separately from hollow shaft motors. The cost of a motor per drive is offset by the advantage that the entire drives can be subjected to a functional test in the manufacturer's operation and can then be supplied to the injection molding unit as a structural unit.

In addition to these spindle drives, at least one, preferably two further spindle drives E are provided, which have spindles 18 ′ and nuts 11 as parts that can move relative to one another. A part of these two parts is arranged on the injection bridge 25 'and the other on the support block 10'. When actuating these spindle drives E by means of the injection motors 51 ', the injection bridge moves relative to the carrier block in such a way that the conveying means 72 is moved axially in a plasticizing unit 17.

The plasticizing unit comprises a plasticizing cylinder 36, which is arranged on the front of the carrier block 10 '. If a conveyor screw is provided as the conveyor 72, a rotary motor 52 ', 52' 'is also arranged such that it drives the conveyor screw in the spray axis s-s. If only one delivery piston is provided, this delivery means also penetrates the carrier block 10 'and is mounted on the injection bridge 25', but a rotary motor is not required in this case.

The rotary motor 52 'is arranged to rotate the conveyor 72 designed as a screw conveyor transversely to the spray axis s-s, preferably projecting upwards, so that the injection molding unit is shortened. This moves the center of gravity of the injection molding unit further towards the center. A favorable speed / torque characteristic for the conveyor 72 can be achieved via a gear 26 ', preferably a bevel gear.

In the exemplary embodiments, the longer part of the spindle and spindle nut of the spindle drive A for the application of the nozzle D as a stable guide element is extended through the injection molding unit. There it has a guide area 31a '. This guide area serves for the precise and positionally accurate guidance of the carrier block 10 'by means of slide bearings 33a and also the injection bridge 25' by means of slide bearings 33b. At the same time, the double function of the spindle 31 'of the hollow shaft motor 73 reduces the mass to be moved when the nozzle is applied.

The double function of the spindle is achieved by dissolving the combination of injection unit and drive unit existing in the prior art. This makes it possible to use the injection motor and the rotary motor as the standard motor at the same time and largely identical in design, which as a side effect of the improved guidance also leads to a cost reduction in the construction of the entire injection molding unit.

In the exemplary embodiment in FIGS. 1 to 6, the guide area is part of a spindle, which in this respect represents the longer part of the spindle drive. In principle, however, the function of the spindle and spindle nut can be interchanged. In this respect, FIG. 7 shows a hollow shaft motor in which the longer part is a tube 110 with an inner profile, into which a rod 111 with a spindle head is purple. In this respect, the purple spindle head is a 'nut' with an external profile, which in FIG. 7 cooperates with the internal profile of the tube 110 via rolling or rolling elements 112. However, direct transmission without rolling elements would also be possible. The tube 110 here represents the rotor 21 of the hollow shaft motor 22, the interior R being able to be vented via the vent 23. The hollow shaft motor illustrated in this way could also perform the guiding function when the tube 110 is extended with this tube as a longer part of the spindle drive, as shown in FIGS. 1 to 6.

2 and 3, the guide areas 31a 'are arranged symmetrically to the plasticizing unit 17 in a horizontal plane. The further spindle drives E and thus also the drive motors 51 'are located in wing regions 25c'. These are also symmetrical to the plasticizing unit, but arranged in a plane that is at an angle to the horizontal. The injection motors 51 'are arranged in a rotationally fixed manner on the injection bridge 25' and rotate the spindles 18 'which cooperate with non-rotatably arranged nuts 11 which are arranged in wing regions 10b' of the carrier block 10 '. At the end of the spindles 18 'there are stops 63'. A planetary gear 51a 'is assigned to each injection motor 51'. While it is only possible in the exemplary embodiments of FIGS. 1 to 5 to design the injection motors 51 'and the rotary motor 52' of identical construction, since the forces occurring are roughly approximated in the Ratio 2: 1, with an arrangement of the rotary motor 52 'according to FIG. 6, a planetary gear 26''can be used as the gear, which is structurally identical to the planetary gear 51a'.

The integrated planetary gears 26 '', 51a 'allow the use of larger spindles, which is equivalent to a longer service life of the drive. At the same time, a larger pitch can be achieved on the spindles, so that there is an optimization in that the torque can be set relatively high and the speed can be reduced at the same time. This also contributes to increasing the service life.

The carrier block 10 'is movable on the spindle 31' up to a stop 32 '. In its front area, the spindle 31 'is held in a holding plate 27. This holding plate is connected to the strips 62 'on which the support block 10' is guided at the level of the machine frame 81. In order to further improve the stability of the entire injection molding unit, a three-dimensional frame is formed in the last two exemplary embodiments of FIGS. 4 to 6 with bar 62 'and holding plate 27 by providing a support plate 82 which then guides the guide region 31a' of the spindle 31 'of the spindle drives A is also supported in the rear area. This ensures stable storage, prevents the injection molding unit from tipping over in the rear area and effectively counteracts vibrations that counteract the service life of the entire unit. This stability is necessary when moving or pivoting the injection molding unit e.g. For injection into the parting line or when moving the injection molding unit for maintenance in a depot is an advantage.

Interchangeable intermediate pieces 13 are arranged between one part of the spindle drive A and the carrier block 10 'or between this part and the stationary mold carrier 35. They lie in the axis aa of the spindle 31 '. The intermediate pieces 13 form at least parts of spars into which the spindles 31 'of the spindle drives A are immersed or which they penetrate. The intermediate pieces 13 can also serve as a guide for the plasticizing unit 17. The intermediate pieces are usually delivered in the shortest and therefore the cheapest form of transportation for delivery to the customer. If it is necessary for the customer, for example, to improve the mixing results or the quality of the material to be plasticized, a longer L / D ratio of the conveying means 72 can be achieved by exchanging the intermediate pieces 13 for longer ones or by lining up intermediate pieces 13. The intermediate pieces can, for example, already be supplied by the manufacturer in a length which corresponds to an L / D ratio of 5, so that the usual L / D ratio can be increased from 20 to 25 by stringing two intermediate pieces together. It is possible to mount the intermediate pieces or the spindles 31 'on a carrier in the area of the stationary mold carrier 35, which can be moved laterally or upwards on the stationary mold carrier 35, in order to thereby make the injection molding unit accessible to a linear sprue, as is the case, for example, with reference to FIG DE-C 42 27 336 is known. The connection with the stationary mold carrier 35 in the direction of the spray axis ss is not broken.

It goes without saying that this description can be subjected to various modifications, changes and adaptations which range from equivalents to the appended claims.

Claims

Patent claims

1. Injection molding unit for a plastic injection molding machine for processing plasticizable materials with

- a plasticizing unit (17) which feeds the plasticized mass via a nozzle (D) in a spray axis (s-s) to a mold (M),

- a conveying means (72) which can be received in the plasticizing unit (17) for conveying the plasticized mass into the mold (M),

- a carrier block (10 ') detachably receiving the plasticizing unit (17),

- a stationary mold carrier (35) for receiving at least a part of the mold (M),

- at least one spindle drive (A), which has a longer part and a shorter part as mutually movable parts, of which the shorter part can be connected in a rotationally fixed manner to the support block (10 ') and the other longer part can be connected to the stationary mold support (35),

- At least one hollow shaft motor (73) which drives a part of the spindle drive (A) for applying the nozzle (D) to the mold (M), characterized in that at least the carrier block (10 ') on a guide area (31a ¹ ) of the longer part is performed.

2. Injection molding unit according to claim 1, characterized in that the longer part is a tube (110) with inner profile (110a) and the shorter part is a head (Ila) with an outer profile.

3. Injection molding unit according to claim 1, characterized in that the longer part is a spindle (31 ') and the shorter part is a spindle nut (78).

4. Injection molding unit according to claim 1, characterized in that two spindle drives (A) arranged symmetrically to the injection axis each have a hollow shaft motor (73) with an integrated planetary gear.

5. Injection molding unit according to claim 1, characterized in that the guide block (10 ') penetrating the guide area (31a ¹ ) serves at the same time an injection bridge (25') for guiding, on which the conveying means (72) is mounted and by means of at least one further The spindle drive (E) can be moved towards the carrier block (10 ') and away from the carrier block for the relative movement of the conveying means (72) with respect to the plasticizing unit (17).

6. Injection molding unit according to claim 5, characterized in that the injection bridge (25 ') carries a rotary motor (52', 52 '') for rotating the conveyor (72) designed as a screw conveyor, which has at least one injection motor (51 ') for the other spindle drives (E) is identical.

7. Injection molding unit according to claim 1, characterized in that the carrier block (10 ') on bars (62') is axially displaceably supported, with which a holding plate (27) is connected, which supports the spindle drives (A).

8. Injection molding unit according to claim 7, characterized in that the bar (62 '), the holding plate (27) and a support plate (82) with the support on the support plate (82) supported guide areas (31a') of the spindles (31 ' ) form a frame.

9. Injection molding unit according to one of the preceding claims, characterized in that interchangeable intermediate pieces (13) between part of the spindle drive (A) and the support block (10 ') in the axis (a-a) of the spindle (31') can be inserted.

10. Injection molding unit according to claim 9, characterized in that the intermediate pieces (13) form at least parts of spars in which the spindles (31 ') of the spindle drives (A) are immersed.

11. Injection molding unit according to one of the preceding claims, characterized in that interchangeable intermediate pieces (13) between part of the spindle drive (A) and the stationary mold carrier (35) in the axis (a-a) of the spindle (31 ') can be inserted.

12. Injection molding unit according to claim 11, characterized in that the intermediate pieces (13) form at least parts of spars in which the spindles (31 ') of the spindle drives (A) are immersed.