WO2003033154A1

WO2003033154A1 - Granulator

Info

Publication number: WO2003033154A1
Application number: PCT/SE2002/001834
Authority: WO
Inventors: Henrik Karlsson; Kurt SJÖBERG; Magnus Blom
Original assignee: Rapid Granulator Ab
Priority date: 2001-10-19
Filing date: 2002-10-09
Publication date: 2003-04-24
Also published as: SE0103500L; SE0103500D0; SE523929C2

Abstract

A granulator comprises an openable infeed section, a first locking device (10), a mill housing with an openable part (5) and a second locking device (12, 13, 17). The first locking device (10) locks the infeed section in a closed position and is, in such instance, blocked by the openable part (5) or a blocking member mounted thereon, or vice versa. The second locking device (12, 13, 17) locks the openable part (5) in a closed position.

Description

GRANULATOR TECHNICAL FIELD

The present invention relates to a granulator comprising: an openable infeed section, a first locking device for locking the infeed section in a closed position, a mill housing with an openable part and a second locking device for locking the openable part in a closed position.

BACKGROUND ART

There are numerous models and types of granulators for plastics and similar materials. A feature common to all of them is that they must occasionally be opened, partly for maintenance and repair and partly for cleaning, in particular when switching between different materials or materials of different colours. Thus, granulators are manufactured so that they are capable of being opened more or less simply.

Since granulators typically contain dangerous components such as fixed and moving sharp blades, there is a need in the art for safety devices so that the sharp components are not accessible while in operation.

There is a number of previously known locking functions in order to keep the granulator in the closed state during operation. A number of examples of such locking functions are clawlike gripping members which grasp around projecting portions in order to hold the granulator together during operation. Such gripping members may be combined with electric make-and- break switches so that the power is supplied to the granulator only when all gripping members are operational. Another method of keeping the granulator in the closed state during operation is that openable sections are bolted in place and that the bolts are advantageously combined with an electric make-and-break function so that the granulator cannot start until all bolts are fully screwed in place.

A feature common to all safety functions which are previously known in the art is that they are quite complex, with numerous construction details and components and often a plurality of moving parts. These aspects imply that safety functions will readily become costly and the risk of wear or failure with consequential operational stoppage and costs for spare parts is substantial. In addition to this problem, there are also difficulties which derive from the fact that the safety devices are not included as a natural part of the design and construction of the granulator but must be retrofitted once the rest of the machine is completed. This means that separate manipulations and actions must be carried out so as to lock the granulator, which are 5 perceived as time-consuming and inconvenient after normal cleaning and maintenance measures have been completed.

A further problem is that not all safety fittings have an automatic monitoring that they are actually being used and this implies that the operator, by carelessness or indolence does not 0 use all safety functions and, as a result, the risk of injury therefore increases.

PROBLEM STRUCTURE

Thus, the present invention has for its object to realise a locking and safety function which is 5 easy to use and reliable and which consists of a few constructional parts.

SOLUTION

The object forming the basis of the present invention will be attained if the granulator ,0 intimated by way of introduction is characterised in that the openable infeed section or the first locking device in the closed and locked state, ^"respectively, is blocked by the openable part or a blocking device mounted thereon.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

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The present invention will now be described in greater detail hereinbelow, with reference to the accompanying Drawings. In the accompanying Drawings:

Fig. 1 shows a granulator according to the present invention in the open state;

SO

Fig. 2 is a close-up view of the locking devices which are included in the granulator according to the present invention;

Fig. 3 is a straight side elevation of the locking devices according to Fig. 2; and Fig. 4 is a detailed view in perspective of a part of a locking member included in the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT

Fig. 1 shows an openable granulator 1 in the open position. The granulator 1 has an openable infeed section 2 with an opening 3 through which the material which is to be granulated is fed in. The infeed section 2 may be provided with further parts so as to facilitate the infeed operation, but for purposes of clarity such parts are not shown in the Figure. In Fig. 1, the openable infeed section is located in the open position, i.e. has been pivoted upwards and rearwards about a substantially horizontal pivot axis in the rear end of the infeed section 2.

The granulator 1 further displays a mill housing 4 which is openable in that it is provided with an openable part 5. In the preferred embodiment, the openable part consists of a pivotal front 5. Inside the mill housing 4, there is a rotor 7 with a number of moving blades 8. Moreover, one or more fixed blades are disposed on the inside of the mill housing 4.

Finished granulate falls down through a grid 9 which has a mesh size corresponding to the maximum permitted size of the granulate. Below the grid 9, there is disposed a receptacle 6 for the finished granulate.

In Fig. 1, the openable part 5 of the mill housing 4 is opened and pivoted outwards about a substantially vertical axis at its one side. The inside of the mill housing 4 is thus readily accessible for cleaning and maintenance. However, such accessibility implies a potential danger if the granulator 1 were to be started without being fully closed.

Fig. 2 shows in greater detail the locking devices which are disposed on the granulator 1. The infeed section 2 is, at its front edge facing towards the front 5 of the mill housing, provided with a first device 10. In the preferred embodiment, the locking device 10 includes a projecting, preferably obliquely inclined plate metal edge or rail along the front edge of the infeed section 2. The oblique plate 10 slopes preferably downwards and extends along the greater part of the front edge of the infeed section 2. The plate 10 projects out a short distance ahead of the infeed section 2. On the openable part or front 5 of the mill housing 4, there is disposed a bent plate 11 which is of a shape and orientation which is complementary to the plate 10. The bent plate 11 constitutes a blocking device for the obliquely inclined plate 10 on the infeed section 2. In the same manner as the latter, the bent plate 11 extends along the greater part of the upper edge of the openable front 5. The bent plate 11 is bent in such a manner that its edge is directed gently upwards and turned to face towards the infeed section 2. The blocking device is of one piece manufacture with the openable front 5, or is secured on it.

When the infeed section 2 is located in its closed position, the first locking device 10 is disposed approximately flush with the blocking device 11 on the openable part 5 of the mill housing 4. If the front 5 of the mill housing 4 is closed, the blocking device 11 will substantially abut wholly or partly against the upper side of the locking device 10 when the infeed section 2 is located in its closed position, so that, as a result, lifting of the locking device 10 is prevented. Hence, the locking device 10 is blocked by the blocking device 11 and it is therefore impossible to open or raise the infeed section 2 when the openable part 5 has been closed.

Fig. 3 shows the construction of Fig. 2 from the side. It is more clearly apparent from this Figure how the blocking device 11 overlaps the first locking device 10.

In order to retain the openable part or front 5 on the mill housing 4, a second locking device is provided. This second locking device is intended to hold the front 5 of the mill housing 4 in the closed position. The second locking device comprises a rail 12 and at least one, but ideally several bolts 17. In the preferred embodiment, the bolts 17 are two in number. The rail 12 is elongate and provided with keyway-shaped recesses 16 for receiving the bolt or bolts 17 and nuts 13 mounted thereon.

When the nuts 13 are untightened, the rail 12 is vertically movable, i.e. reciprocally as far as the size of the keyway-shaped recesses 16 permit. When the rail 12 is located in its lower position, it may be removed since the nuts 13 can pass through the greater part of the keyway- shaped recesses 16. In this instance, the nuts 13 do not need to be backed off entirely from the bolts 17, but they can pass through the recesses 16 and the granulator be opened. On the other hand, when the nuts 13 are tightened and the rail 12 is located in an upper position, the openable front 5 is totally closed. At the same time, the first locking device 10 is thus blocked on the infeed section 2 and, thereafter, cannot be raised until the openable front 5 is once again pivoted upwards.

The nuts 13 and bolts 17 are replaceable by one-piece bolts. In such an event, the head of each bolt is of the same order of magnitude as a nut 13 and can, in the same manner, pass through the greater part of the keyway-shaped recesses 16 when the bolt has been released but not completely removed. The shape of the head is designed for engagement with a tool.

It is per se conceivable that the openable front 5 be closed and locked without the infeed section 2 first having been lowered down. In order to prevent the granulator 1 from starting when the infeed section 2 is still open, there is yet a further safety function. The infeed section 2 is provided with an electric switch 14 in which a key-shaped device 15 may be inserted. The key-shaped device 15 is disposed on the upper region of the rail 12. Only when the key- shaped device 15 is inserted in the electric switch is it possible to start the granulator 1. Thus, it is ensured that both the infeed section 2 and the openable front 5 are closed while the granulator 1 is in operation. The key is then fixedly locked in the electric switch 14 when the granulator mill is in operation.

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The key-shaped device 15 is fully insertible in the electric switch 14 only when the rail 12 provided with keyways is located in the locked position, i.e. when the infeed section 2 is closed.

'5 Fig. 4 shows in detail the key-shaped de ice 15 on the upper region of the rail 12. The electric switch 14 is, in the preferred embodiment, provided with a further safety function, such as time relay, so as to ensure that the key device 15 cannot withdrawn from the switch 14, i.e. that the machine cannot be opened before the rotor 7 with its moving blades 8 has fully stopped and parked. With the aid of the time relay and the locking of the key device 15, it is

SO thus impossible to open the granulator 1 before a certain, predetermined time has elapsed from when the power to the granulator 1 was cut off. The time delay is selected so that the rotor 7 has reliably stopped and parked. Other devices for checking that the rotor is stationary may also be utilised in this context. The different, above-described safety functions thus co-operate to form a holistic unit. The overlapping blocking device 11 prevents the infeed section 2 from being moved upwards. The openable part 5 with the blocking device 11 is locked in the closed position with the aid of the rail 12 provided with keyways, with associated bolts 17 and nuts 13. In its turn, the rail 12 is 5 provided with the key-shaped device 15 for contact with the electric switch 14 on the infeed section 2 when this is located in the closed position. Thus, all safety functions are mutually dependent on one another in a chain sequence, and it is impossible to start or continue to run the granulator 1 without all links in this chain remaining intact.

0 The different safety devices and locking devices are integrated into the design and construction of the granulator. A normal closure procedure entails that the safety devices are all made operational simultaneously. The safety functions are perceived as neither inconvenient nor particularly time-consuming, which eliminates the risk that they are intentionally disengaged. Furthermore, the construction displays a minimum number of

5 moving parts for a minimum need for maintenance and repair. Seen as a whole, the costs for the safety devices represent but a fraction of the total costs for the granulator 1.

DESCRIPTION OF ALTERNATIVE EMBODIMENTS

O In the foregoing, it was described how the different parts of the granulator 1 are intended to be closed in a given sequence. It is, naturally, also possible to construct the granulator 1 and its associated locking devices in such a manner that the machine is intended normally to be closed in a different sequence. For example, a construction is conceivable in which the openable front 5 is first closed and that the infeed section 2 alone or together with other

'5 locking devices blocks the openable front 5. In a corresponding manner, the construction is modified so that a safety chain corresponding to the above-described is obtained. With the guidance of the foregoing description, such modifications are likely to be obvious to a person skilled in the art.

SO Correspondingly, the second locking device 12, 13, 15, 17 may be varied and possibly replaced by some other locking device known to a person skilled in the art which fulfils a corresponding function. The present invention may further be modified without departing from the scope of the appended Claims.

Claims

WHAT IS CLAIMED IS:

1. A granulator comprising: an openable infeed section (2), a first locking device (10) for locking the infeed section (2) in a closed position, a mill housing (4) with an openable part (5) 5 and a second locking device (12, 13) for locking the openable part (5) in a closed position, characterised in that the openable infeed section (2) or the first locking device (10) in the closed and locked state, respectively, is blocked by the openable part (5) or a blocking device (11) mounted thereon.

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2. A granulator comprising: an openable infeed section (2), a first locking device (10) for locking the infeed section (2) in a closed position, a mill housing (4) with an openable part (5) and a second locking device (12, 13) for locking the openable part (5) in a closed position, characterised in that the openable part (5) or a blocking device (11) disposed thereon in the closed and locked position, respectively, is blocked by the openable infeed section (2) or the

L5 first locking device (10).

3. The granulator as claimed in Claim 1 or 2, characterised in that the second locking device (12, 13, 14, 15) including a blocking member (14, 15) which, in a closed position, is disposed to prevent opening of the openable part (5) or its locking device (12, 13) and which,

10 in an open position, is disposed to permit such opening; and that a blocking device is disposed to permit transfer of the blocking member to its open position only when the rotor (7) of the granulator (1) is reliably at rest.

4. The granulator as claimed in any of Claims 1 to 3, characterised in that the second 15 locking device (12, 13, 14, 15) in the closed position is also in electric or mechanical contact with the infeed section (2) so as to ensure that this is also closed while the granulator is in operation.

5. The granulator as claimed in any of Claims 1 to 4, characterised in that the first SO locking device (10) is integrated with or secured on the infeed section (2) so that they are movable simultaneously.

6. The granulator as claimed in any of Claims 1 to 5, characterised in that the blocking member (11) on the openable part (5) of the mill housing (4) is simultaneously movable therewith.