Note: Descriptions are shown in the official language in which they were submitted.
113(~0~
This invention relates to a method of forming a composite article
of shaped metal and a moulded synthetic plastics material.
Such composite articles are used in a wide range of industries,
including the manufacture of motor vehicles, electrical goods, precision
and agricultural machines, toys, furniture and office goods. Hitherto they
have been prepared from separate parts separately shaped, or by moulding
plastics material onto metal parts, which for example may subsequently be
shaped.
One example of a moulding operation is so-called 'outsert'
moulding. According to this process composite articles are obtained by
fitting the inside of a mould with a pre-formed metal component and injecting
a synthetic plastics material into the mould whereby the resin becomes
integrated with the metal by flowing into apertures provided on the metal
component. Such a technique is used widely for manufacturing components for
tape-recorders and watches (see "Plastics", vol. 26, No. 12, pages 52-53).
The insert or outsert shaping process is a very economical one
but it is still not entirely satisfactory. For example separately carrying
out the shaping of the metal component and moulding the plastics component
thereto requires a plurality of machines and operations. Special precautions
have also to be observed which result in a high proportion of rejects.
When a metal base plate is used as a component in the outsert
method, while it is relatively easy to place and pile a number of flat base
plates one on another and then to automatically feed them successively to a
shaping machine, with metal plates having curves or bends therein a special
conveyor or like means is required to handle them, automated processing then
becoming very difficult.
The present invention is based upon using a mould assembly of
a conventional injection moulding apparatus which also acts as a shaping
device for the metal component, simultaneously effecting injection and
shaping of the synthetic resin which is added to form the composite article.
~7
1~3(~070
As a result simplicity and accuracy of the production of the components are
significantly improved and a reduction in the rejection rate is achieved.
The invention provides a method of forming a composite article
of shaped metal and moulded synthetic plastics material, comprising disposing
a metal blank in a closable injection mould adapted to receive a metal blank,
the said mould being provided with means whereby the metal blank may be
shaped, and/or cut, introducing mouldable synthetic plastics material into
the mould and simultaneously with the shaping and/or cutting of the metal
blank by the said shaping and/or cutting means the mouldable plastics material
in the mould is moulded onto the metal blank to form a shaped and moulded
composite article.
In particular the mould parts, together with any cores or pins
utilized in the shaping processl are moved during clamping and opening of
the mould or during the time when injection and solidifying of the synthetic
plastics material is being carried out.
The metal which is used for one component of the composite
article produced according to the invention may be a sheet metal blank, e.g~
cold roll steel plate or aluminium plate, and the synthetic resin plastics
material used for the other component may be a thermoplastic resin e.g.
polyacetal, or a thermosetting resin.
There is no particular criterion for the shaping process, which
may be a deformation step e.g. bending or drawing, or a cutting operation
e.g. perforation.
The metal blanks may be formed from a continuous feed stock fed
to the moulding during the method of the invention. Thus a continuous metal
feed stock may be used in the form for example of block, rod or plate.
The use of preformed blanks is acceptable however if the overall
process is not thereby rendered too complicated.
In conventional shaping of parts having a cut-out deformation of
the e.g. metal part occurs in the lateral direction due to the shaping
~ :
- ~13QI~)70
pressure of resin but deformation is avoided in the steps of the present
invention. Furthermore using metal or other components having a preformed
complicated shape there has been a limitation to the formation of cavities
therein for the synthetic resin to be made composite therewith, but with
the present invention, such limitations can be reduced since the metal
component is shaped during the filling of the mould with the mouldable plastics
material.
The use of conventional injection moulding apparatus for the
method of the invention is dependent on limitations imposed by the movement
of the mould parts, and the degree of shaping which may be achieved may be
limited using conventional machines. The type of moulding apparatus should
therefore be selected bearing in mind the degree of shaping and accuracy
desired.
In the shaping of metal blanks in the method of the invention,
since a considerable force is exerted on the metal part, it is desirable to
clamp the metal part before effecting the shaping operation.
For the purpose of illustration, but not of limitation, embodiments
of the invention are hereinafter described with reference to the accompanying
drawings, in which:
Figure 1 illustrates the formation by outsert moulding wherein
a metal blank is bent during clamping the mould. Figure l(A) is a cross-
sectional representation of the mould in the open position showing a metal
blank in position and Figure l(B) shows a perspective view of the formed
composite article;
Figure 2 illustrates the production of a moulded article by the
method of the invention which is provided by outsert moulded spigots joined
by a runner obtained by a shaping process which is a shallow-drawing. Figure
2A shows a cross-sectional view along the line I-I of Figure 2C, of an open
mould in vertical section;
Figure 3 shows another embodiment with a nail-like member;
.~ -
~13Q07()
Figure 4 illustrates the cutting out of a metal blank from a
continuous moving metal strip;
Figure 5 shows an example of processing a block of raw material
into a base and making the resulting base composite with a resin;
Figure 6 shows an example of providing a cut-out in the method
of the present invention;
Figure 7 shows an example of insert shaping;
Figure 8 shows an example wherein a part of the mold is replaced
at the time of pressing and at the time of making parts composite.
; lO In the arrangement of the mould of Figure lA, l and 2 are the
mould parts having mould cavities 3 and 4 respectively. A metal blank 5
having an aperture 6 is disposed between the mould parts. The mould part
1 has side members 7 and 7' for exerting a bending action on the metal blank
during mould closure.
When the mouldable synthetic resin introduced into the mould is
moulded onto the metal plate, the metal blank is bent by the closing action
of the mould, and a spigot 9 is moulded to the unbent surface 8 to provide
a moulded article as shown in Figure lB.
,
In Figure 2A the mould parts 1 and 2 are provided with mould
cavities 3, 3', -4, 4' respectively, the said cavities 3, 3' being joined
by a surface 25 of level below the general level of the die part 1, and the
said cavities being joined by a surface 28 standing proud of the die part 2.
The interposed metal blank 26 has two perforations 27, 27' corresponding to
~ the aforesaid cavities in the mould parts wherein spigots 10, lO' are outsert
;~ moulded thereon, joined by a shallow-drawn runner 11 (Figure 2C).
In another embodiment illustrated in Figures 2B and 2D, a core
28 is provided in one mould part 2 which corresponds to the position of a
~: cavity in mould part 1. On closure and after moulding a composite product
is obtained as shown in side section in Figure 2D, wherein an indentation
12 is provided underneath the moulded part ll. The said moulded part 11 may
-- 4 --
~,.~: .
~3(~070
be a runner. If desired the core 28 may be movable (e.g. by the action of
a screw thread as shown) and moved to provide the indentation 12 after the
mould has been clamped. The deformation of the metal blank due to the
shrinkage of the runner is reduced by such drawing.
Figure 3 shows an example of providing a sharp nail-like member
33 in one of the mould parts 2 which is movable longitudinally so that a
perforation is made in the metal blank 4 during closure of the mould parts
1 and 2 (Figure 3A) to produce after moulding a composite part shown in
perspective in Figure 3B and in section in Figure 3C.
Figure 4 illustrates the cutting out of a metal blank from a
continuous moving metal strip 45 by the cutting action of moving side walls
33, 33' of mould part 1 during closure of the mould parts 1 and 2 (Figure
4A). During the passage of the strip past the mould a blank is separated
therefrom leaving an aperture in the strip as shown in Figure 4D. During
moulding the blank is perforated by mould core portion 4 to produce a
composite product shown in perspective in Figure 4B and in vertical section
in Figure 4C.
If desired the said core portion may be movable as referred to
in the description of Figure 2.
Figure 5 shows an example of processing a block o~ raw material
into a base by means of press and making the resulting base composite with
a resin. In the arrangement of the mould of Figure 5~A), numerals 1 and 2
show a retained plate; numeral 53, a press mould which is at the same time
a cavity; numeral 54, a raw material; and numeral 55, a cavity for pressing
the base, Figure 5(B) shows the cross-section of the product. In addition,
numeral 53i shows the location of the press mould 53 at which the mould has
been projected at the time of pressing. Namely, a raw material 54 is pressed
into a shape as shown by numeral 54' of Figure 5(B), and thereafter the
press mould is withdrawn to the location shown, whereby a body of synthetic
resin 55 is formed inside a cavity.
il3C~070
Figure 6 shows an example of providing a cut-out in the method
of the present invention. In the arrangement of mould parts 1, 2 of Figure
6A the corresponding mould configurations 2, 63 provide a cutting action to
the blank during mould closure providing an aperture 66 in the final product
65 (Figure 6B). At the same time a spigot 67 is outsert moulded through a
preformed aperture in the blank.
Figure 7 shows an example of insert shaping. In the arrangement
of mould parts 1 and 2 of Figure 7A, cavities 74 and 75 are provided. During
closure of the mould parts, the lip portion 76 of mould part 1 exerts a
bending action or the edge 73 of the metal blank, and at the same time an
edge portion is insert moulded to produce a composite article as shown in
Figure 7B.
Figure 8 shows an example wherein a part of mould is replaced
at the time of pressing and at the time of making parts composite. Figure
8(A) shows an arrangement of the mould at the time of pressing, showing a
press mould 1 and 2, and a retained plate 83. Futher, Figure 8~B) shows an
arrangement of the mould at the time of shaping, wherein numeral 84 shows
a shaping mould. At first a nail 86 is provided on the base 83 by means of
the core 85. Next, the press mould 1 is replaced by the shaping mould 84
20~ and a body of synthetic resin is shaped inside a cavity 87, whereby a
product having an appearance as shown in Figure 8(C) is obtained. Such a
replacement is carried out by sliding or rotation.
In the drawings, two sheet moulds are mainly shown as the mould,
but, as in the case of conventional injection moulding, more complicated
moulds may be optionally employed in carrying out the present invention.
Further, as for the material quality for the mould, hardness is required
at the time of processing a hard material, while corrosion resistance is
required for the cavity.
: : . : :
