The present invention relates to an adjustable mould consisting of matched mould members. The invention also relates to an object which is manufactured by using the said adjustable mould.

In order to manufacture an object by means of casting, injuction-moulding or other such method, there is needed a cavity, i.e. a mould, corresponding in both shape and measure to the desired object. The prior art moulds are produced by mechanizing and by casting. Such moulds are unique and costly.

The purpose of the present inventi-on is to eliminate the aforementioned drawbacks and to provide a method for an adjustable mould, which can be employed repeatedly and in the production of various different objects. This is realized by means of the characteristic novel features of the invention which are apparent from the appended patent claims.

The most remarkable among the advantages of the present invention is the fact that the mould expenses are decreased. The same mould or parts thereof can be used in the manufacture of several different castings or other such pieces. The adjusting of the mould is a simple procedure, and it can be automated. Thus the mould is suited to be employed with considerably smaller production series while making castings or other such pieces than the currently used moulds.

The adjustable mould according to the invention is particularly well suited to be used in plastic industry, specially in the series production of packages or

protective shells made of polystyrene or other such light cellular plastic. The manufacturing of a complex mould becomes unnecessary, and consequently the delivery times of such packages are remarkably shortened. The surface of the package if formed of protruding, step-like surface elements, which offer several pneumatic points of support for the product to be packed. Thus the produced package is extremely well suited for its respective purpose.

The invention is below described with reference to the appended drawing, where Figure 1 is an illustration of an adjustable mould according to the invention, seen from the top, a, and seen in cross-section along the line A-A, b; Figure 2 is an illustration of a mould element, seen in lengthwise cross-section, a, and seen from the top, b.

The adjustable mould consists of two mould members: the first, i.e. the female mould member 1, and the second, i.e. the male mould member 2, which are matched with each other. In between the two, the proper casting or other such piece is manufactured. The male mould member 2 comprises the frame 3 and a number of mould elements 4. The mould elements 4 fill up the inner part of the frame 3. The frame 3 is also provided with the flange 3a, where the respective flange la of the female mould member 1 is fastened for instace by means of screws.

The female mould member 1 also comprises a frame lb, which has a shape corresponding to the frame 3 of the male mould member 2. The frame 3 of the male mould 2 can be fitted within the frame lb of the female mould 1, advantageously against the shoulders lc thereof. The female mould 1 is provided with the front plate 21, which comprises the aperture 22 for a filling pistol or equivalent device.

At the back of the male mould 2, on the opposite side with respect to the female mould 1, there is embedded and fastened the locking plate 11. The locking plate 11 covers the whole of the back part of the frame 3. On top of it, there also is adjusted the back plate proper 20.

The mould elements 4 are elongate or rod-like members which are slidably interfitted at the sides 5. They have a regular shape in cross-section - in this case they are quadratic as is seen in figure 2b, and their dimensions are 10 x 10 mm. Their length may vary for example between 10 - 30 cm. The mould elements 4 are positioned within the box-like frame 3 lengthwise against each other in an overlapping fashion, at right angles with respect to the whole frame 3. They can also be moved in a direction transversal to the frame, their position can be adjusted and they can be locked into place for instance by means of the frame 3.

The mould element 4 is additionally provided with the recess 6, as is seen in figure 2a. It is connected, by means of the channels 7 and 8, to both ends 9 and 10 of the element 4 respecti ely. This recess 6 is part of the cavity or boring 14, which is made in the direction of the lengthwise axis B-B of the element 6, at the other end 10 thereof. The mouth opening 10' of the boring 14 is provided with a threading 15, whereinto there is fitted an adjusting screw 12 or other similar adjusting device. The adjusting screw 12 passes through the opening 13 located in the locking plate 11 so that the head 16 or other such holding member of the adjusting screw 12 remains on the opposite side of the locking plate 11 with respect to the mould element. The opening 13 corresponds to the cross-sectional area of the adjusting screw, or is somewhat larger than that. The diameter of the head 16 of the adjusting screw 12

is larger than the diameter of the aperture 13 at least in one direction, and the said head 16 is embedded in the locking plate 11.

The mould elements 4 are locked into place by suitably pressing them together. For this, the frame 3 of the male mould 2 is provided with a special tightening ledge 17. This ledge is a tightening hoop or equivalent member which is fitted into one or several grooves 18 of the frame and follows and conforms to its inner edge, and it can be lengthened or shortened for example by means of an adjustable screw.

The adjustable mould of the invention is manufactured in the following fashion. According to models, the box-like and often polygonal frames lb, 3 of the moulds 1, 2 are constructed. In the grooves 18 located in the frame 3 of the male mould 2, there is placed a tightening ledge 17 of a suitable length. The locking plate 11 is provided with- perforations, where the distances between the openings 13 or holes are regular and depend on the cross-sectional area of the mould elements 4, i.e. of the distances between the central points of the mould elements. A piece which can be matched into the opening 13 in the frame 3 is cut off the locking plate 11 of the above description, and the said piece is fitted in the frame 3. Into the openings 13 of the locking plate 11, which openings are located inside the frame 3, there are installed the adjusting screws 12, whereafter the mould elements 4 are fastened to the adjusting screws.

The male mould 2 is provided with a back plate 20 of a suitable size.

The adjustable mould is made ready for operation so that

the back plate 20 is taken off the mould and the tightening ledge 17 is loosened. Now the mould elements 4 can move freely within the limits set by the lengths of the adjusting screws 12. The template is placed in the filling space 23. The mould elements 4 are pressed against the template, whereafter the screws 12 are lightly fastened to the locking plate 11, and the back plate 20 is fixed into place. The tightening ledge 17 is tightened, so that the mould elements are pressed tightly and firmly against each other. Now the mould is ready for operation.

The adjustable mould according to the invention can be employed particularly in the manufacture of polystyrene packages and protective shells. In that case it is advantageous to arrange underpressure in the mould filling space 23 during the filling stage in order to make sure that the polystyrene grains, which are fed in through the opening 22 by means of a filling pistol or equivalent, absolutely fill the whole space 23. Underpressure is arranged in the empty space 24 of the male mould 2 corresponding to the filling space 23 for instance by sucking air from the mould through another opening made in the locking plate 11 and the back plate 20, in which case underpresssure is simultaneously created also in the filling space 23 through the recesses 6 and channels 8, 9 of the mould elments 4. On the other hand, the gases and vapours created in the mould filling stage are discharged from the filling space 23 through the said channels 8, 9 and recesses 6. Moreover, through the said paths 6, 8, 9, cooling water can be conducted up to the surface of the object formed in the filling space.

When the polystyrene package is ready, the front plate 21 is dismantled. Into the space 24 there is conducted pressurized air, which flows through the paths 6, 8 and 9

of the mould elements 4 and effects the object located in the filling space by pushing it out of the mould. The mould is cleaned, whereafter it is immediately ready for a successive filling.

An object manufactured by employing the adjustable mould of the invention has a special surface structure. The arched surfaces of the said object are provided with steplike bulges or protruding surface elements. Their area

corresponds to the cross-sectional area of the mould element 4, and in the embodiment according to the figures of the drawing, they are quadratic and of the dimensions 10 x 10 mm. This kind of surface structure in the polystyrene packages manufactured by employing the mould of the invention clearly has an advantage whe'n compared to other corresponding packages. The product placed within the package rests supported by numerous pneumatic bulges or » supporting points, so that the protective nature of the package is particularly enforced.

The invention has above been explain'ed mainly with reference to one preferred embodiment thereof. Naturally it is by no means desired that the invention should be restricted to the said embodiment olnly, but the invention can be modified in many ways without departing from the scope of the invention defined in the indepedent claim. The mould elements can have shapes other than the above described, and they can be provided with grooves and/or bulges at the sides in order to make their fitting together easier. Instead of a recess, each mould element can be provided with a uniform groove or boring which is for instance round in cross-section. In the said boring, straight bars can be installed instead of the adjusting screws, and these bars penetrate the locking plate, where they can be locked after adjusting the position, for

example by pressing them into place by means of another locking plate. Furthermore it is pointed out that both mould members, both the female and the male mould member, may contain other adjustable mould elements. The frames of the mould elements are manufactured of a relatively thin aluminium profile or equivalent, which frames can then suitably be joined for instance on top of each other in order to make sure that the mould becomes sufficiently deep. If the adjustable mould is used for manufacturing for instance polystyrene packages, the frame itself may be simply quadratic, and its appearance does not necessarily have to be in any ways connected to the appearance of the product to be packed.