EP0813944A2 - Mill for pulverizing solids - Google Patents

Abstract

A mill for the reduction of plastic items has a hopper (10) opening into the pulveriser housing (8) where the cutter (6) is located. There is a feeder (14) to compress the items, partly in the hopper, with an Archimedean screw made from a helical spring. The axis of the cutter is horizontal and that of the feeder is vertical. The feeder direction is offset from the opening to the hopper. The hopper has an inclined wall (28) so that it tapers downwards from the opening, and the feeder axis is beside the opposite wall. The motor (18) for the feeder and cutter can be exchanged, being bolted to a flange outside the bearing plate (34).

Description

The invention relates to a solids mill for comminuting solids according to the preamble of claim 1.

Such a solid or plastic mill has a grinding housing in which a rotor equipped with cutting knives or other cutting devices is rotatably mounted, which, in cooperation with fixed cutting knives (stator), comminutes the plastic parts fed through an insertion shaft, for example sprues from an injection molding process. The regrind is discharged via a regrind container or suction shaft located below the rotor in the direction of gravity and, for example, returned to the injection molding machine and mixed there with the starting material. Accordingly, plastic mills of this type are used, for example, for recycling production residues in injection molding. The generic solid mills are set up as so-called side mills next to the injection molding machine, so that the molded parts to be ground - for example the sprues - can be removed from the (injection molding) tool by hand or using a handling device and thrown into the chute.

Particularly in the case of tools with multiple uses, in which the plastic melt is guided to the individual cavities via a sprue distributor, the bulky shapes of the sprues (sprue spider) can cause them to build up in the tapering area of the insertion shaft, so that access to the Grinder housing is blocked.

To prevent this blocking of the chute, side mills are used in which the chute is laterally offset next to the grinding housing and the plastic parts supplied to the chute are fed to the cutting unit via a conveyor and / or compacting screw. This means that the plastic parts are conveyed out of the insertion shaft by the screw conveyor, compacted and fed to the actual cutting device. Such side mills with a horizontal screw conveyor have a high chute when operated as an side mill to ensure safety of engagement, in which the sprues can open before they reach the feed area of the screw.

In contrast, the invention has for its object to provide a solids mill with which the plastic parts can be prevented from accumulating in the insertion chute with a minimal device-related structure.

This object is solved by the features of claim 1.

As a result of the measure of integrating the intake device in the insertion shaft, the plastic parts to be ground can already be drawn into the insertion device in the insertion shaft, so that the plastic parts can practically not be jammed up.

Another advantage of the solids mill according to the invention compared to the conventional solutions with a feed device with a horizontal direction of action can be seen in the fact that by the substantially vertical direction of action or conveying direction of the feed device, the solids mill can be constructed much more compact, so that it is much closer to the Injection molding machine can be made than was the case with conventional solutions.

The design of the solid-state mill according to the invention thus saves considerable installation space, so that the traffic routes in the injection molding operation are only insignificantly reduced by the auxiliary mills.

Since the feed device is accommodated in the insertion shaft, no separate housing has to be provided for the feed device, so that the outlay on device technology is also considerably reduced compared to conventional solutions.

It is particularly advantageous if the feed devices are designed as screw conveyors. However, other feed devices can also be used, through which the plastic parts can be transported from the shaft to the regrind. For example, the screw conveyor can be replaced by a coil spring element.

A particularly compact solids mill is obtained if the axis of rotation of the cutting device runs in the horizontal direction and the conveying axis of the feed device is arranged in a vertical plane to the cutting device axis. However, it is also possible that the angle between the conveying axis of the feed device and the axis of rotation of the cutting device is less than 90 °.

For safety reasons, it is preferred if the feed device is arranged at a predetermined distance from an insertion opening of the insertion shaft, so that an operator cannot accidentally reach into the feed device.

In a preferred exemplary embodiment, the insertion shaft is designed with a rectangular cross-sectional shape, one side wall being inclined, so that the cross section of the insertion shaft is directed downward towards the grinding housing reduced. The side wall opposite this inclined wall is arranged parallel to the axis of the feed device, the space between the feed device and this side wall being reduced to a minimum, so that the operator cannot accidentally intervene in this area.

Maintenance of the solid matter mill according to the invention is particularly simplified if the feed device can be exchanged in one piece with its drive. In this case, a storage bracket is advantageously attached to the housing of the insertion shaft, via which the feed device and its drive are mounted.

To minimize the risk of injury, a slip clutch can be provided between the drive motor and the conveying element.

Due to the articulated mounting of the screw conveyor, it can swing out of the way when bulky regrind is being pulled in, so that jamming of the regrind and thus blocking of the feed chute can be prevented.

Depending on the requirements, the drive motor can be arranged inside or outside the chute.

Further advantageous embodiments of the invention are the subject of the other subclaims.

A preferred embodiment of the invention is explained in more detail below with the aid of schematic drawings.

Fig. 1

eine Seitenansicht einer erfindungsgemäßen Feststoffmühle im Teilschnitt;

Fig. 2

eine Draufsicht in Richtung A auf die Feststoffmühle aus Figur 1 und

Fig. 3

eine Vorderansicht der Feststoffmühle aus Figur 1 im Halbschnitt.

Show it:

Fig. 1

a side view of a solid mill according to the invention in partial section;

Fig. 2

a plan view in direction A of the solid mill from Figure 1 and

Fig. 3

a front view of the solid mill from Figure 1 in half section.

1, the solid matter mill according to the invention has a mobile frame 2 on which a drive unit 4 is mounted, which drives a cutting device 6, which is surrounded by a grinding housing 8 of the solid matter mill. On the upper part of the grinding housing 8 in FIG. 1, an insertion shaft 10 is supported, through which the plastic parts to be ground - in the present case sprues - can be inserted into the grinding chamber 12 of the grinding housing 8. In the solids mill according to the invention, a feed device 14 is mounted on the chute 10, which essentially consists of a screw conveyor 16 and a drive motor 18. A regrind container 20, in which the regrind is collected, is fastened to the end of the grinding housing 8 on the foot side in FIG. 1. It is usually provided that the collected regrind is sucked out of the regrind container 20 and fed back to the injection molding machine as regrind.

As already mentioned at the beginning, solid mills of this type are used as auxiliary mills in injection molding technology, these being assigned to one or more injection molding machines. The sprues resulting from the injection molding process are thrown into the chute 10 via a conveying device, by hand or via a handling device, and are conveyed out of the chute's chute area to the grinding chamber 12 by the screw conveyor 16, the sprues being compacted. The sprues fed to the grinding chamber 12 are then ground by the cutting device 6 and the ground plastic is taken up in the ground material container 20 and, if necessary, returned to the injection molding machine.

2 has a rectangular cross-sectional shape with three side walls 22 to 26 running vertically to the plane of the drawing in FIG.

At the upper end of the chute 10 in FIG. 1, a chute 30 is formed through which the sprue can be inserted into the chute 10. The rear side wall 24 opposite the inclined wall 28, hereinafter referred to as rear wall 24, is reset step-wise in the illustration according to FIG. 1, so that the clear width of the insertion shaft 10 is reduced in this area by a horizontal step 32. This horizontal step 32 serves as a support surface for a bearing bracket 34 which is fastened to the horizontal step 32 with a support flange 36. The support flange 36 carries a hub-shaped bearing bush 38 which passes through the horizontal step 32 and projects downwards (view according to FIG. 1) into the interior of the insertion shaft 10. The bearing bush 38 is supported on the support flange 36 via support struts 40 distributed over the circumference.

The drive motor 18 is fastened on the large surface of the support flange 36 which is distant from the horizontal step 32, an output shaft 42 of the drive motor 19 passing through the support flange 36 and the horizontal step 32 and projecting into the interior of the bearing bush 38.

This output shaft 32 is non-rotatably connected to the screw conveyor 16 so that it can be rotated when the drive motor 18 is actuated. To support the screw conveyor 16, two bearings 44, preferably ball bearings, are provided in the bearing bush 38, which are arranged at an axial distance from one another, so that a play-free mounting of the screw conveyor 16 is ensured. Furthermore, the relative large axial distance between the two bearings 44 prevents lateral deflection of the freely projecting screw conveyor 16.

In an alternative embodiment, the screw conveyor 16 is pivotally mounted on the drive motor 18, so that the end of the screw conveyor 16 which is distant therefrom can deviate by a few centimeters in the case of bulky regrind in order to avoid blocking. For this purpose, for example, a joint can be arranged between the drive motor 18 and the screw conveyor 16, which enables a predetermined deflection. In this exemplary embodiment, the side wall 24 is arranged somewhat further from the axis of rotation of the screw conveyor 16 than is the case with the exemplary embodiment shown in FIG. 1.

The axis 46 of the screw conveyor 16 is arranged at a parallel distance (view according to FIG. 1) to the rear wall 24, this distance being chosen such that the peripheral edges of the screw conveyor 16 end at a short distance from the rear wall 24, so that an operator can use the Fingers cannot reach into the space between rear wall 24 and screw conveyor 16.

In the embodiment according to the invention, the conveyor spiral of the screw conveyor 16 begins at a predetermined vertical distance from the insertion opening 30, so that an operator cannot generally reach the screw conveyor 16 with his hands. These measures further increase the operational safety of the solid matter mill according to the invention.

An additional safety measure is to connect the screw conveyor 16 to the output shaft 42 via a slip clutch, so that in the event that an operator gets his fingers between the screw conveyor and the side walls 22, 24 and 26 surrounding it despite the aforementioned measures , not seriously injured can be, since the slip clutch prevents the screw conveyor 16 from rotating further.

In the exemplary embodiment shown, the drive motor 18 is provided outside the insertion chute 10. Of course, the drive motor 18 can, however, also be stored within the insertion shaft 10, the bearing bracket 34 then being fastened to the inner walls of the shaft. The variant shown in Fig. 1 has the advantage that the drive motor 18 and the screw conveyor 16 can be removed as a unit from the chute 10 by loosening the bearing bracket 34, so that the maintenance of the solid mill is extremely simple.

The freely projecting end of the screw conveyor 16 opens within the upper end section of the grinding housing 12 in FIG. at a predetermined distance of about 30 mm above the cutting knife of the cutting device 6, so that the sprues are forcibly conveyed into the area of the cutting knife.

The structure of the cutting device 6 and the grinding housing is essentially already known from the prior art, for example from G 93 15 733 and the other utility model G 295 09 271 of the applicant, so that only the essential components are to be described below. With regard to further constructive details, reference is made to the aforementioned utility model of the applicant, the content of which is to be included in the disclosure of the present application.

As can be seen in particular from FIGS. 1 and 3, the frame 2 is preferably provided with wheels 48 which allow the solid mill to be easily moved. The wheels 16 are provided in a known manner with a braking system in order to prevent the solid mill from being moved unintentionally.

A frame-shaped support bracket 50 is supported on the frame, to which the drive unit is attached with an electric motor 52, a control unit 54 and a transmission gear. A rotor shaft 56 (FIG. 3) passes through a base plate 58 which forms the rear wall of the grinding housing 8.

A plurality of partial rotors 60 arranged one behind the other in the axial direction are fastened to the end section of the rotor shaft 56 protruding into the grinding chamber 12, each partial rotor 30 carrying three cutting knives 62. 3, the sub-rotors are arranged offset in the circumferential direction from one another on the rotor shaft 56, so that the cutting blades 62 of the individual sub-rotors are also offset in the circumferential direction from one another in the grinding chamber 12. This offset arrangement of the cutting blades 62 prevents the sprues from jamming. In the exemplary embodiment shown, four partial rotors 30 are arranged axially one behind the other on the rotor shaft 56, so that the cutting knives cover the entire axial length of the rotor shaft projecting into the grinding chamber 12. Of course, other rotor designs can also be used.

Provided in the base plate 58 are two support beams 64 and 66 which project into the grinding chamber 12 and on which fixed stator knives 68 are fastened which, in interaction with the cutting knives 62, form the cutting device.

A screen 82 is clamped between the two support beams 64 and 66, which has an outer diameter adapted to the outer circumference of the partial rotors 60 and extends from the support beams 64, 66 in a semicircle. To further support the screen 82, two projecting stud bolts 84 are provided on the base plate 58, on which the screen rests. This construction has the advantage that the sieve 82 can be removed in a simple manner when the grinding housing 8 is removed is. For further details, please refer to utility model G 93 15 773. In the case of rotors with small-toothed knives, a screen can be dispensed with entirely.

Above the stator blades 68 are formed on the inside walls of the grinding housing 8 obliquely downward deflectors 86 which are intended to ensure that the ground material is guided towards the gap between the stator blades 68 and the cutting blades 62. The deflectors 86 are arranged at a short distance from the fastening means of the stator knives 68, so that no regrind can accumulate between the deflector 86 and stator knives 68.

On the base plate 58 of the support bracket 50, the other peripheral walls of the grinder housing 8, the insertion shaft 10 and the grist container 20 are supported.

The cuboid-shaped grinding housing 8, which is open at the bottom towards the regrind container 20, is connected to the support bracket 50 via a joint device 62. This articulation device 62 can be arranged either on one side wall of the grinding housing or else on both side walls of the grinding housing and allows the grinding housing 8 and thus the insertion shaft 10 and the grinding material container 20 to move away from the base plate 58 in the horizontal direction. the hinge device 62 is fastened to the side wall of the grinding housing 8 or to the support bracket 50 via two fastening tabs 72. Two hinge plates 70 are provided between the two fastening tabs and are connected to one another via hinge bolts. In the contact positions of the grinding housing 8 shown in FIGS. 1 and 3, the two hinge plates 70 are pivoted relative to one another so that they protrude outward in a V-shape.

The mounting bracket 72 of the joint device 62 on the grinding housing side and the two hinge plates 70 can be supported on a guide bar 74 which is fastened to the support bracket 50.

During the pulling of the grinding housing 8 from the base plate 58, the fastening tab 72 and the two hinge plates 70 can slide on the facing side edge of the guide bar 74, so that the joint device 72 does not have to absorb the entire weight of the grinding housing 8 and the insertion shaft 10, but rather the forces be introduced into the support bracket 50 via the joint device 62 and the guide bar 74.

The grinding housing 8 is held in its sealing closed position by quick-release devices 76 arranged on both sides. By means of suitable lever constructions it can be provided that the grinding housing is moved away from the base plate 58 by opening the quick-action clamping devices 76. A corresponding construction has already been described in the utility model G 93 15 773 of the applicant.

In order to simplify the engagement and disengagement of the grinding housing 8, 8 handles 78 are provided on the side walls of the grinding housing.

According to FIG. 3, guides 80 are fastened to the lower end sections of the grinding housing side walls, in the guide grooves of which a peripheral edge of the grinding material container 20 can engage, so that this can be removed from the grinding housing 8 along the guides 80.

The regrind container 20 has a V-shaped bottom, a suction nozzle is provided in the apex area in the side wall, into which the suction pipe of a conveyor can be inserted.

The sprues to be ground are thrown into the chute 10 through the chute 30, which, according to the plan view according to FIG. 2, has a maximum cross-sectional area in the area of the chute 30. Due to the effect of gravity, the sprue slides down along the inclined wall 28 until it reaches the feed area of the screw conveyor 16 and is thereby forcibly conveyed towards the regrind. The speed of the screw conveyor 16 is relatively low and is approximately eight revolutions per minute. Of course, other speeds can also be selected. Due to the stable mounting of the screw conveyor, it is not laterally deflected when the bulky sprues are being conveyed, so that reliable conveying is ensured. The sprues are compressed by the screw conveyor 16 and forcibly conveyed into the grinding chamber 12, where they are then crushed by the cutting device 6 and the resulting granulate with a predetermined grain size falls into the ground material container 20. The granulate is then sucked out of this and fed to the injection molding machine as regrind.

To clean the solids mill - for example when changing materials - the two quick-release fasteners 76 are opened and the grinding housing 8 is moved away from the base plate 58, so that the articulation device 62 - or more precisely its hinge plates 70 - from the kink position shown in FIG. 3 to its extended position to be brought. During this moving-down movement of the grinding housing 8 and the associated stretching movement of the joint device 62, the grinding housing 8 is supported on the support bracket 50 via the joint device 62 and the guide bar 74, so that tilting or tilting of the grinding housing 8 and the insertion shaft 10 is prevented. When the grinding housing 8 is removed, the cutting device 6 and the sieve 82 are freely accessible, so that they can be cleaned or replaced in a simple manner. After cleaning the mill, the grinding housing 8 is pushed back towards the base plate, the grinding housing 8 is supported via the joint device 62 and the guide bar 74, so that an exact guidance is ensured. After reaching the contact position on the base plate 58, the two quick-action clamping devices 76 are hooked onto the grinding housing 8 and this is pressed into its sealing position against the base plate, so that the mill is functional again.

In the event that maintenance of the screw conveyor 16 is required, the drive motor 18 and the screw conveyor 16 can be removed as a unit by loosening the bearing bracket 34 from the insertion shaft 10. In this way, the vertical screw according to the invention can be exchanged in a simple manner, so that the solid matter mill can also be delivered as a retrofit mill in which the vertical screw can be supplied as an option.

The insertion shaft 10 can - as proposed in G 295 092 71 - be pivotally mounted on the grinding housing 8, which can also be designed as a separable housing.

Disclosed is a solids mill for comminuting solids, preferably plastic parts, with an insertion shaft which opens into a grinding housing in which a cutting device for the solids is received and with a feed device for compressing and conveying the solids. The feed device is arranged approximately in the vertical direction in the insertion shaft, so that space can be saved compared to conventional solutions with a horizontal feed device arranged outside the insertion shaft.

Claims (13)

Solid mill for comminuting solids, preferably plastic parts, with an insertion shaft (10) which opens into a grinding housing (8) in which a cutting device (6) for the solid is received, and with a feed device (14) for compressing and conveying of solid matter, characterized in that the feed device (14) is arranged at least in sections in the insertion shaft (10) in such a way that the plastic parts can be conveyed in the feed shaft (10) by means of the feed device (14). Solid material mill according to claim 1, characterized in that the feed device (14) has a screw conveyor (16). Solid material mill according to claim 1, characterized in that the feed device (14) has a helical spring-shaped conveying element. Solid mill according to one of the preceding claims, characterized in that the axis of the cutting device (6) is arranged in the horizontal direction (in relation to the standing surface) and the axis of the drawing-in device (14) in the vertical plane to the cutting device axis. Solid material mill according to one of the preceding claims, characterized in that the feed device is arranged at a distance from an insertion opening (30) in the insertion shaft (10). Solid material mill according to claim 4, characterized in that the insertion shaft (10) has an inclined wall (28) so that a rectangular cross-sectional shape of the insertion shaft (10) widens towards the insertion opening (30), and that the axis of the feed device (14) is arranged at a predetermined distance from the rear wall (24) opposite the inclined wall (28). Solid mill according to one of the preceding claims, characterized in that a drive motor (18) of the feed device (14) and its conveying element (16) can be exchanged as a unit. Solid matter mill according to claim 7, characterized in that the conveying element (16) is mounted on a bearing bracket (34) of the insertion shaft (10) and that a drive motor (18) is flanged to the bearing bracket (34) outside the insertion shaft (10). Solid mill according to one of claims 1 to 7, characterized in that the conveying element (16) and the drive motor (18) are mounted within the insertion shaft (10). Solid material mill according to one of claims 7 to 9, characterized in that a slip clutch is provided between the drive motor (18) and the screw conveyor (16). Solids mill according to one of the claims 2 to 10, characterized in that the screw conveyor (16) is articulated on one side. Solid mill according to one of the preceding claims, characterized in that the total height of the solid mill is approximately 1300 mm. Solid material mill according to one of the preceding claims, characterized in that the feed device (14) ends at a distance of 10 mm to 50 mm, preferably approximately 30 mm, above the cutting device (6).

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