Processing

Please wait...

Settings

Settings

Goto Application

1. WO1996003269 - MACHINE WITH FAST CHANGE TOOL SYSTEM

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

MACHINE WITH FAST CHANGE TOOL SYSTEM

This invention relates to a machine with a fast change tool system- The invention is particularly
applicable to injection moulding machines, but is not limited to this application since the fast change tool system provided may be applicable in other moulding and similar process machines.
The industrial production of moulded articles by injection moulding is well known. In this technique, a "tool" having an appropriate mould cavity is loaded into an injection moulding machine, and the injection moulding machine operated to produce the required mouldings. The "tool" comprises at least two parts which are mounted respectively on a fixed and a movable platen of the
injection moulding machine. Often, the tool will comprise several relatively movable parts. Such tools must be manufactured to great accuracy and must be very robust in order to withstand the mechanical stresses to which they are subject in use. As a result, injection moulding tools are both expensive and very heavy. The change of mould tool which is necessary each time the article to be moulded by a particularly injection moulding machine is to be changed is a considerable inconvenience to the moulding manufacturer. In order to change a tool several individual fixings
securing each part of the tool to the injection moulding machine must be released and a hoist or the like must be connected to the tool to remove the tool from the working area of the injection moulding machine. A new tool must then be manoeuvred into position into the working area of the machine, correctly aligned, and the respective tool parts clamped to the fixed or moving platens. Additionally, in many cases a movable ejector plate within the tool must be connected to the ejector piston of the injection moulding machine. The process of tool changing is accordingly both difficult and time consuming and as a result each time a tool change is required the injection moulding machine must be taken out of production for a significant period. Since injection moulding machines are large and expensive pieces of equipment such down-time represents a significant
overhead in the operating of the machine .
With a view to avoiding the difficulties outlined above injection moulding machines have been proposed which include automatic or semi-automatic tool changing apparatus. Such machines are, however, extremely expensive and complex. Also, the automatic tool changing systems cannot easily be applied to existing machines and cannot, in general, operate with existing mould tools. Thus, the need exists for a fast change tool system which can be fitted relatively
inexpensively to a new or existing injection moulding machine and which is able to accommodate existing mould tools .
According to the present invention there is provided a machine with a fast change tool system
comprising: at least one platen to which a tool is to be secured; fixed guide means on the platen; a backplate on the tool adapted to mate with the guide means to position the backplate at a predetermined location on the platen; and releasable clamping means for clamping the backplate in the said predetermined position.

Typically, the machine will comprise two platens which face each other and to which respective parts of the tool are secured. In this case, both platens will be provided with appropriate guide means and both tool parts will be fitted with appropriate backplates.
In use of an embodiment of the invention the spacing between the platens is adjusted to be equal to the overall size of the proposed tool plus a small working clearance. The tool is then slid into position so that the backplates mate with the guide means to position each backplate at a predetermined and precisely defined position on each platen. The clamping means are then installed to clamp the backplates in the said predetermined positions. By this means, a tool may be rapidly and precisely located within a relatively short period of time. Removal and changing of the tool is accomplished by releasing the clamping means, sliding the tool out of the tooling area of the machine to disengage the backplates from the guide means, re-adjusting the space in between the platens if necessary, and inserting a new tool as described above.
In a simple embodiment of the invention the guide means consist of fixed guides provided either directly on the platen or on a suitable adaptor plate secured to the platen. Typically, a pair of guides are provided to locate each backplate laterally, and a stop is provided to locate the backplate vertically. Once the necessary guide means have been secured to the platens is merely necessary to provide each tool with appropriate backplates with the tool parts secured to the backplates at the correct position. Since the tools may be changed without disturbing the connections between the tools proper and the backplates, each time the tool is loaded the tool will be at exactly the correct position relative to the platens of the machine.

In an embodiment of the invention capable of accepting a range of backplates the guide means have a plurality of predetermined fixed positions relative to their respective platens. In order to insert a particular tool the guide means would firstly be located at the
predetermined position corresponding to the backplate of that tool, and the tool would then be loaded as described above. If the machine is then to operate with a tool having a different size of backplate the guide means will be repositioned after removal of the first tool.
Preferably, the fast change tool system is
arranged such that the tool may be inserted between the platens and into its final working position by a single linear movement, for example a vertically downward movement or a horizontal movement. To this end, in the preferred embodiment of the invention the ejector plate of the tool is provided with a coupling which automatically mates with a coupling provided on the ejector piston of the machine as the tool slides into position.
The invention will be better understood from the following description of a preferred embodiment thereof, given by way of example only, reference being had to the accompanying drawings wherein:
Figure 1 is an exploded trimetric diagram
illustrated schematically the tool changing system of the present invention with a mould tool located raised above the tooling area of the machine;
Figure 2 illustrates the tool system of Figure 1 with the tools located on the platens and the platens in the closed position;
Figure 3 is an elevational view, partly broken away, of the tool system of Figures 1 and 2;
Figure 4 is an exploded trimetric view showing in greater detail a portion of the embodiment of Figure 1;
Figures 5A and 5B are detailed views illustrating portions of the tool system of Figures 1-4; and
Figures 6A and 6B are cross-sectional view
illustrating further details of the system of Figures 1-4.
Referring firstly to Figures 1 and 2 there is illustrated part of an injection moulding machine 1. The machine includes a fixed platen 2 and a movable platen 3 interconnected by tie-bars 4. As will be appreciated by those skilled in the art the platens 2,3 are interconnected by four tie-bars, one of which has been omitted from Figures 1 and 2 in the interests of clarity. The remaining
constructional details of the injection moulding machine will be known to those skilled in the art and are not relevant to the present invention.
Each platen has secured thereto guide means which, in use, cooperate with backplates 5,6 secured to the
respective parts 7A, 7B of a tool 7 to be used in the machine. As more particularly shown in Figure 4, in the illustrated embodiment of the invention the guide means 8 comprise pads 9,10 and a stop 11 (Figure 1) secured directly to the platen 2 by means of appropriate threaded fasteners which engage the conventional threaded fixing holes 12 provided on the platen 2. Although in the illustrated embodiment of the invention the guide means are fixed directly to the platen it will be appreciated that, as an alternative, the guide means may be mounted on an adaptor plate which is itself fixed to the platen by an suitable means.
The pads 9,10 each provide a guide surface 13,14. The spacing of the guide surfaces corresponds to the overall width of the backplates 5,6 so that when a respective backplate is located between the guide surfaces 13,14 the backplate and thus the tool part connected to it are
correctly located, in the horizontal direction, relative to the corresponding platen 2,3. With the lower edge of the backplate resting on the stop 11 the backplate, and thus the tool part attached to it, are correctly located in the vertical direction relative to the corresponding platen 2,3. Thus, with the backplate 5,6 located between the pads 9,10 and resting on the stop 11 the tool part connected to the back plate will be precisely correctly located relative the platen.
Preferably, the guide surfaces 13,14 are located only slightly inwardly of the vertical planes defined by the inner edges of the front and rear pairs of tie-bars 4 respectively. Thus, the width of backplate corresponding to the spacing of the guide surfaces 13,14 will be very
slightly less than the horizontal spacing of the tie-bars 4. This arrangement will allow the tool to be introduced into the working area between the platens in a vertically
downward direction between the upper pair of tie-bars, whilst maximising the size of backplate 5,6 with which the particular machine may be used.
Whilst in the preferred embodiment of the
invention the tool is introduced vertically downwardly into the working area between the platens it should "be
appreciated that the arrangement of the guide means can be located 90° displaced from that illustrated in the drawings allowing the tool to be introduced horizontally into the working area between the platens from either the front or the rear of the machine, according to the location of the stops 11.
Suitable clamp members 15 are provided for
clamping the backplates 5,6 against the platens 2,3 after the backplates have been correctly positioned by the guide means .
The particular clamp means illustrated will be described in greater detail hereinafter, but for the moment it should be noted that the function of the clamp means is to hold the backplates 5,6 firmly against the platens 2,3 in the correct location as defined by the interengagement of the backplates and the guide means. In the broadest aspect of the invention any clamp means suitable for this purpose may be utilised.
In use, starting from a configuration in which no tool is present within the working area of the injection moulding machine, a tool is loaded by first moving the movable platen 3 to a spacing from the fixed platen 2 corresponding to the overall length of the tool 7 (including the backplates 5,6) plus a small working clearance. The complete tool 7, including the backplates 5,6, is then lowered vertically between the tie-bars 4 by suitable means (for example an over-head hoist) so that the backplates 5,6 slide into the required location between the guide surfaces 13,14. To facilitate positioning of the tool suitable lead-in surfaces may be provided. For example, each pad 9,10 may have a sloping lead-in surface 16 at the upper end thereof. The tool is lowered until the lower edges of the backplates 5,6 engage the corresponding stops 11. If desired, the stops 11 may incorporate a centering profile which
cooperates with an appropriate profile on the backplates to assist in centering the tool on the platen. Once the tool is in position resting on the stops 11 the clamp members are fastened to secure the backplates in position and any necessary auxiliary services (e.g. cooling water supplies, temperature sensors, etc.) are connected to the tool 7.
If, as will usually be the case, the tool part 7B connected to the movable platen 3 incorporates an ejector mechanism, means are preferably provided for automatically coupling the ejector mechanism of the tool to the ejector piston of the injection moulding machine as the tool is lowered into position. To this end, the ejector piston 17 of the injection moulding machine preferably extends
slightly beyond the movable platen 3 into the working zone between the platens and is provided with a profile which automatically couples with a mating profile on the ejector mechanism of the tool as the tool is lowered into position. The exact form of the coupling is not critical to the present invention, but, in the illustrated embodiment, comprises a head on the rod 17 defined by a groove machined in the rod, the head being adapted to be received within an appropriate socket provided on the ejector mechanism of the tool. A slot 18 is provided in the backplate 6 to allow passage of the head of the ejector piston 17 as the tool is lowered into position.
Changing of a tool is accomplished by
disconnecting any service connections to the tool, releasing the clamping members, and lifting the tool vertically outwardly of the machine. A new tool having backplates 5,6 adopted to mate with the guide means may then be lowered into position. The backplates of the new tool may be identical to those of the tool which has been removed, but fundamentally the only requirement for the new backplates is that the surfaces which they present to the guide means are at the correct position relative to the tool to ensure that the tool will be correctly located when the new backplate is in engagement with the guide means. If the new backplate is of different thickness from that removed the clamping means will be adjusted as necessary, as described in more detail hereinafter.
With the above described arrangement the tools are quickly and precisely located relative to the platens and can quickly be removed. This considerably simplifies and speeds up the tool changing process and accordingly reduces the down time of the injection moulding machine associated with the tool changing.
Whilst, in a simple embodiment of the invention, the clamp members need consist of no more than simple clamps which fix the backplates to the platens after location of the backplates by the guide means, in the illustrated embodiment of the invention the clamp members are of a somewhat more complex construction, but offer significant additional advantages.
Referring first to Figure 4, each clamp member 15 is mounted on a carrier 19 which is itself a sliding fit in a pocket 20 provided in the pad 9. In the illustrated embodiment four such pairs of clamp members and carriers are provided, each having a corresponding pocket 20 in one of the pads 9,10. Each clamp member 15 includes a
projection 21 which mates with a pocket 22 provided in the corresponding carrier to locate the clamp member on the carrier. The carrier and clamp member may be locked in the desired correct position by means of a bolt 23 which extends through the clamp member and the carrier into screw threaded engagement with one of the holes 12 provided on the platen 2 or adaptor plate (if an adaptor plate is used). A spring 24 is located between each clamp member 15 and the
corresponding carrier 19 to bias the clamp member 15 away from the carrier and its associated platen.
In use, each carrier 19 may be located in one of two alternative positions in its corresponding recess 20. In the first of these positions, as illustrated in Figure 5B, the carrier is located substantially entirely within the pocket 20 and accordingly the end face 25 of the carrier does not project beyond the corresponding guide surface 13,14 of the pad in which the carrier is mounted. With the carrier in this position the clamp member 15 may be located in any of a number of indexible positions relative to the carrier. The number of positions in which the clamp member may be located will be determined by the form of the
projection 21 and pocket 22, but in general it is envisaged that the clamp member will be locatable in any one of four positions spaced 90° apart in the rotational direction.
In each of these positions one of the edges of the clamp member will be presented to the backplate. Typically, in one of the indexible positions of the clamp member 15 the surface of the clamp member presented to the backplate will not extend beyond the guide surface 13,14 of the pads 9,10. In this position, therefore, the clamp member will not interfere with movement of the backplate in the longitudinal direction of the injection moulding machine. This position of the clamp members may be particular helpful when loading certain tools into the working area of the machine. In each of the other possible indexible positions of each clamp member 15 the clamp member will present a different clamp surface to the backplate located between the pads 9,10. Two such positions are illustrated in Figures 6A and 6B. In Figure 6A the clamp member 15 presents a clamp surface 25 corresponding to a first thickness 26 of backplate 5. When in the position illustrated in Figure 6B the clamp member 15 presents a clamp surface 27 corresponding to backplate thickness 28.
In addition to the position of the carrier
described above, the carrier 19 may be removed from its corresponding pocket, rotated through 180° and reinserted until the end face 25 bottoms against shoulders 29 provided in the recess 20. In this position the opposite end face 30 of the carrier 19 will be presented to the backing plate. This end face 30 will be located proud of the guide surface 13,14 of its associated pad, as illustrated in Figure 5A. In this position of the carrier members, the end surfaces 30 of the carrier members define alternative guide surfaces corresponding to a relatively smaller size of backplate 5. Thus, by positioning the carrier members in the alternative position in which the end faces 30 are presented, the injection moulding machine may be used with tools having an alternative, smaller backplate size. This may be
particularly suitable for relatively small tools. It will, of course, be appreciated that any particular installation may be supplied with a number of alternative clamping members and carriers to facilitate the use of a wide range of backplate sizes. However, it is in general envisaged that a machine capable of operating with two alternative widths of backplate will be sufficient for all practical purposes .
In the alternative position of the carriers 19 the clamp members may be utilised in any one of their available indexible positions as described above. It will be noted that the two alternative positions of the carriers 19 will present the through bore in the carriers for the bolts 23 to two different threaded holes 12, thereby enabling the bolt 23 to be tightened directly onto the platen in either of the alternative positions of the carriers.
It should be noted that, in certain aspects of the invention, the clamp means may themselves define guide surfaces by the tool backplates. In this case, with the clamp means in their released position guide surfaces on the clamp means will locate the backplate, and the clamp means are then tightened to clamp the backplate back to the platen. If the clamp means are indexible as described above a multiplicity of guide surfaces each corresponding to a different width of backplate may be provided by appropriate indexing of the clamp means.
It will be appreciated that in the case of a machine having two platens, as described above, the guide means and clamping means provided on the two platens will, in general, be identical, thereby enabling identical backplates to be used on the two tool parts. However, in its broadest aspect the present invention covers an
arrangement in which there is only one platen in a machine, and accordingly only one set of guide means, backplate and clamping means are provided.