Device for injection molding articles while simultaneously forming patterns thereon

A strip-like pattern sheet has a plurality of patterns and register marks spaced apart from each other by a predetermined distance in its longitudinal direction. The pattern sheet is transported from a supply roll to a take-up roll in such a way that it covers the opening of a female mold. At the upper stream of the female mold, the register marks are detected so that a pattern-sheet-holding-and-transferring means holds the pattern sheet at a predetermined position and heats it. The pattern sheet is displaced by one pitch so as to cover the opening of the female mold. The softened pattern sheet is pressed by a compressed air against the cavity surface of the female mold with the cavity being evacuated. Thereafter the holding-and-transferring means is returned to its initial position and the female and male molds are mated so that molten resin is injected into the molding cavity defined between the female and male molds so that a pattern is imprinted on the surface of a molded article or finished product. The pattern may be imprinted or transferred in an efficient manner and the precise registration between the pattern and the surface of the molded article or finished product can be attained.

BACKGROUND OF THE INVENTION 
The present invention relates to a method and device for molding articles 
by injection molding while simultaneously imprinting on or transferring 
onto the molded articles patterns on a continuous sheet. 
A method and device for molding articles by injection molding while 
simultaneously imprinting or transferring patterns on a continuous sheet 
on or to the molded articles mean that a sheet bearing patterns is pressed 
against the cavity surface of a female mold by applying the pressure or by 
evacuating the cavity of the female mold and a molten plastic compound is 
injected through a male mold into the cavity defined by the male and 
female molds which are mated together, whereby the patterns are imprinted 
or transferred on the surface of molded articles or finished products. 
According to the prior art, as described in detail in Japanese Patent 
Publication No. 19132/1975, an injection molding machine with a male mold 
and a female mold is used. An operator inserts a sheet bearing patterns 
between the male and female molds and the air under pressure is blown out 
through the male mold so that the sheet may be firmly pressed against the 
cavity surface of the female mold. Thereafter, molten plastic material is 
injected through the male mold into the cavity defined by the male and 
female molds which are mated together so that the sheet bearing patterns 
may be imprinted on the surface of the molded articles and then the 
finished products are ejected. 
It is apparently inefficient that an operator inserts a pattern bearing 
sheet (to be referred to as "a pattern sheet" in this specification) 
between the male and female molds every time when the articles are molded. 
Moreover, the pattern sheet must be inserted correctly between the male 
and female molds so that the pattern sheet may be correctly registered 
with the surfaces of molded articles. Furthermore, such operation is 
cumbersome. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a method and device for 
molding articles by injection molding while simultaneously imprinting or 
transferring patterns on a sheet on the molded articles so that molded 
articles with patterns may be continuously molded and the correct 
registration between patterns and the respective surfaces of molded 
articles may be attained. 
According to the present invention, there is provided a method for molding 
an article by injection molding while simultaneously imprinting on or 
transferring onto the molded article a pattern on a continuous pattern 
sheet, wherein prior to the injection of molten plastic material, a 
softened pattern sheet is pre-molded by pressing said pattern sheet under 
the air pressure against the cavity surface of a female mold, and wherein 
the molten plastic material is injected from a male mold into the cavity 
defined between said male and female molds mated together with each other 
to integrate the molded article with the pattern on said pattern sheet, 
said method comprising: (a) disposing said pattern sheet which has a 
plurality of patterns and register marks spaced apart from each other by a 
predetermined distance in its longitudinal direction in such a way that 
said pattern sheet is transported so as to cover the opening of said 
female mold; (b) detecting the register marks on said pattern sheet at the 
upstream of said female mold so that 
pattern-sheet-holding-and-transferring means holds said pattern sheet at a 
predetermined position with respect to each pattern thereon; (c) 
transporting by one pitch said pattern sheet so as to cover said opening 
of said female mold while heating said pattern sheet; (d) pressing the 
softened pattern sheet against the cavity surface of said female mold, 
thereby pre-molding said pattern sheet; (e) returning said 
pattern-sheet-holding-and-transferring means to its initial position; and 
(f) injecting the molten plastic material through the male mold into the 
cavity defined by said male and female molds which are mated together, 
whereby the molded article is integrated with said pattern sheet. 
According to the present invention, there is further provided a device for 
molding an article by injection molding while simultaneously imprinting on 
or transferring onto the molded article each pattern which is printed on a 
continuous sheet in a predetermined pitch, wherein the pattern sheet is 
pressed under the air pressure against the cavity surface of a female mold 
prior to the injection molding, and molten plastic material is injected 
from a male mold into the cavity defined by said male and female molds 
which are mated together, whereby said pattern sheet and the molded 
article are integrated with each other, said device comprising: (a) a 
sheet supporting means comprising a pattern-sheet supply roll and a 
pattern-sheet take-up roll which are so arranged that said pattern sheet 
is transported so as to cover the opening of a female mold; (b) a 
pattern-sheet-holding-and-transferring means for holding a predetermined 
part of the pattern sheet on which the pattern to be imprinted on or 
transferred onto the article is formed and transferring the part thereof 
to the opening of the female mold, said means comprising: (i) a cover 
means having a plurality of air passages in opposed relationship with the 
pattern sheet and a heating means for softening the pattern sheet, (ii) a 
frame means which coacts with said cover means so as to clamp said pattern 
sheet therebetween and which is movable in unison with said cover means, 
(iii) a transfer means which reciprocates said 
pattern-sheet-holding-and-transferring means by one pitch between the 
adjacent patterns on said pattern sheet, (iv) detection means mounted on 
said cover means or said frame means for detecting the register marks 
which are marked apart from each other by a predetermined distance on said 
pattern sheet, and (v) a shift means responsive to the outputs from said 
detection means for shifting the cover means and frame means in unison 
with each other to the predetermined position with respect to the pattern 
on the pattern sheet; and (c) an air operating means connected to the air 
passages of the cover means to suck the pattern sheet against the heating 
means of the cover means and to press the pattern sheet against the cavity 
surface of the female mold. 
The above and other objects, effects, features and advantages of the 
present invention will become more apparent from the following description 
of a preferred embodiment thereof taken in conjunction with the 
accompanying drawing.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 is shown an article or finished product molded in accordance with 
the present invention. A pattern sheet 2 is attached onto the surface of 
the article 1. A flower pattern 10 is imprinted on the raised portion of 
the article and characters or letters 12 are imprinted at the lower 
portion of the pattern sheet 2. 
In FIG. 2 is shown in vertical cross section an injection molding machine M 
in accordance with the present invention. It comprises a male mold 16 
securely attached to a stationary plate 20 and a female mold 18 securely 
mounted on a movable plate 24 which is movable toward or away from the 
male mold 16 by means of a ram 22. An ejector 26 is disposed adjacent to 
the movable plate 24 for ejecting a molded article out of the mold by pins 
(not shown). 
An injection device 28 is extended through the stationary plate 20 and the 
male mold 16 and is communicated with a nozzle 30 so that a molten plastic 
material is forced through the injection device 28 and the nozzle 30 into 
the cavity of the female mold 18. 
A pattern sheet 32 is vertically transported between the male and female 
molds 16 and 18; that is, the pattern sheet 32 is unrolled from a supply 
roll 34 and is taken by a take-up roll 36. The travel of the pattern sheet 
32 from the supply roll 34 to the take-up roll 36 is controlled by an 
upper and a lower guide roll 38. The supply roll 36 is biased in the 
clockwise direction under the force of a spring (not shown) while the 
take-up roll 36 is biased in the counterclockwise direction under the 
force of a spring (not shown) in FIG. 2 so that tension is exerted on the 
pattern sheet 32. 
The pattern sheet 32 has desired patterns which are spaced apart from each 
other by a suitable distance in the longitudinal direction. The pattern 
sheet 32 is set according to the type of forming patterns on the article. 
That is, when the sheet 32 is so set that the patterns thereon face the 
male mold 16, the patterns are formed on the backside of the sheet 
covering the molded article. On the contrary, when the sheet 32 is so set 
that the patterns thereon face the female mold 18, the patterns are formed 
on the front surface of the sheet covering the molded article. When only 
ink for forming the patterns on the pattern sheet 32 is transferred onto 
the surface of the molded article, the pattern sheet 32 must be so set 
that the patterns thereon face the male mold 16. 
The pattern sheet 32 is provided with register marks T which are spaced 
apart by a predetermined distance in the longitudinal direction. Each 
register mark T comprises a horizontal line segment a for determining the 
vertical position (the x-direction) of the sheet 32 and a vertical line 
segment b for determining the horizontal position (the y-direction) 
thereof. That is, the register mark T is in the form of +, but it is to be 
understood that the horizontal line segment a and the vertical line 
segment b may be marked separately. 
Over the two molds are provided a pattern-sheet-holding-and-transferring 
device 100 which transfers a pattern on the sheet 32 by the predetermined 
distance onto the female mold 18 while holding and heating the sheet 32. 
The device 100 has a supporting plate 101 on which a moving plate 102 
slidable vertically is mounted via a known shift mechanism including a 
drive screw and a servomotor (not shown). On the moving plate 102 is 
mounted a cover member 44 which can slide in the lateral direction (the 
direction perpendicular to the direction in which the moving plate 102 can 
slide on the supporting plate 101) via the same shift mechanism as above. 
The cover member 44 faces a frame member 46 which is movable integrally 
with the member 44 on a base plate 103 but cannot separate away from the 
surface of the base plate 103. The base plate 103 is provided between two 
vertical rails 42 which extend vertically on the opposite sides of the 
female mold 18. Furthermore, the female mold 18 is adapted to project 
through an opening formed in the base plate 103. 
From the sides of the frame and cover members 44 and 46 are projected four 
arms 104 and 105, respectively, between which two air-cylinders 106 are 
provided as shown in FIG. 4. The air-cylinders 106 function to pull the 
cover member 44 toward the frame member 46 to hold the pattern sheet 32. 
Instead of the air cylinders 106, oil cylinders or electric motor may be 
used. The supporting plate 101 has a plurality of legs 101a at its four 
corners, which engage with the rails 42. 
The frame member 46 is disposed in opposed relationship with a cover member 
44 which has a heating unit 44a embedded therein. The frame member 46 is 
in the shape of a letter U. The cover member 44 is provided with a 
plurality of air passages 50 which in turn are communicated with a common 
air passage 51 which in turn is communicated with an air operating means 
including a vacuum pump, a compressed air source and a change-over valve 
(all not shown). The heating unit 44a may comprise a heat plate, a 
sintered metal plate or a high-frequency heating plate. 
The sheet-holding-and-transferring device 100 is vertically moved by means 
of an air cylinder 52, the upper end of which is pivoted at 52 to a 
stationary frame (not shown) and the lower end of which is pivoted to the 
supporting plate 101. 
Detectors such as photosensors 54 are located at the positions above and 
below the cover member 44 or the frame member 46 and are adapted to detect 
the register marks T on the pattern sheet 32. It is preferable to provide 
two detectors 54 for determining the position in the X-direction and two 
detectors 54 for determining the position in the Y-direction. 
Pressure members 56 are disposed in opposed relationship with each other 
below the female mold 18 and are adapted to clamp the pattern sheet 32. 
The pressure members 56 are moved toward or away from each other by means 
of an air cylinder (not shown) mounted on the movable plate 24. The 
pressure members 56 are extended transversely of the pattern sheet 32 and 
one of the pressure members 56 is held stationary while the other is moved 
toward or away from the one. 
The female die 18 is provided with air passages 58 which will be described 
in more detail hereinafter. 
The mode of operation will now be described. First the cover member 44 and 
the frame member 46 are moved in unison with each other away from a 
reference position to detect the register mark T. When the detectors 54 
detect the horizontal line segment a of the register mark T, a control 
circuit (not shown) stops the operation of the moving mechanism. 
Thereafter the cover and frame members 44 and 46 are caused to move in the 
Y-direction by means of another moving mechanism. When the detectors 54 
detect the horizontal line segment b, the control circuit stops the 
operation thereof. Thus the cover plate 44 is displaced to a predetermined 
position with respect to a pattern on the pattern sheet 32. 
Thereafter, the vacuum pump is operated so that the air is sucked through 
the air passages 50 and the common air passage 51 of the cover member 44, 
whereby the pattern sheet 32 is firmly sucked against the heating element 
44a. Next the air cylinders 106 is actuated so that the cover member 44 is 
caused to move toward the frame member 46, whereby the pattern sheet 32 is 
clamped between the cover and frame members 44 and 46. At this time, as 
the moving plate 102 and the cover member 44 are adapted not to be 
separated away from the supporting plate 101 and the moving plate 102, 
respectively, the cylinder 52 is slightly rotated toward the frame member 
46 around the axis 52a. 
Thereafter the two moving mechanisms are operated again so that the cover 
and frame members 44 and 46 are returned to their reference or initial 
positions. Then, the piston rod of the air cylinder 52 is extended as 
shown in FIG. 5 to cause the sheet-holding-and-transfer-ring-device 100 to 
move downward along the rails 42 and are stopped at the predetermined 
position in opposed relationship with the female mold 18. At this time, 
the pattern sheet 32 is unrolled and advanced by a predetermined distance 
(that is, one pitch between the adjacent patterns). The pattern sheet 32 
is heated and softened by the heating unit 44a during its travel. Since 
the frame member 46 is in the form of a letter U, it may surround the 
female mold 18 and the cover plate 44 upon which the pattern sheet 32 is 
pressed closes the cavity of the female mold 18. In this case, the pattern 
on the pattern sheet 32 is in predetermined positional relationship with 
the bottom 18a of the cavity of the female mold 18. 
Under these conditions, the air in the cavity of the female die 18 is 
evacuated through the air passages 58 while the compressed air is blown 
through the common air passage 51 and the air passages 50 of the cover 
member 44 by changing the change over valve of the air operating means so 
that the pattern sheet 32 is forced to be separated from the surface of 
the heating unit 44a and pressed against the cavity surfaces of the female 
die 18 as shown in FIG. 6. If the cavity of the female mold 18 is deep, a 
part of the cover member 44 may be moved toward the cavity of the female 
mold 18 while holding the pattern sheet 32 so that when the cavity of the 
female mold 18 is evacuated, the pattern sheet may be pre-molded without 
being expanded excessively. 
So far it has been described that after the cavity of the female mold 18 
has been evacuated, the compressed air is supplied through the common air 
passage 51 and the air passages 50 so that the pattern sheet 32 is pressed 
against the surfaces of the cavity of the female mold 18, but it is to be 
understood that while the compressed air is supplied through the air 
passages 50 in the manner described above, the air in the cavity of the 
female mold 18 may be discharged through the air passages 58 without 
evacuating operation. In the latter case, the female mold 19 must be 
provided a relatively large number of air discharge passages 58. However, 
the openings of such passages 58 are imprinted on the surface of the 
molded articles or finished products. As a result, such arrangement is not 
preferable in practice. Furthermore, when the air remains in the cavity of 
the female mold 18, undesired recesses are formed on the surfaces of the 
molded articles or finished products. However, according to the present 
invention, the cavity of the female mold 18 is evacuated as described 
above, so that it is not needed to provide a plurality of air discharge 
passages. Accordingly, the trace of the openings of the air passages 58 is 
almost not left on the surfaces of molded articles or finished products. 
Thereafter, the air cylinder 106 is so actuated that the cover member 44 is 
moved away from the frame member 46 to release the sheet 32. After this, 
the piston rod of the air cylinder 52 is retracted to cause the device 100 
to return to their initial positions as shown in FIG. 2. In this case, the 
pressure members 56 clamp the pattern sheet 32 to prevent the pattern 
sheet 32 from moving upwardly. 
Thereafter, the ram 22 is actuated so that the female mold 18 is moved 
toward the male mold 16. Molten plastic material is injected through the 
injection device 28 and the nozzle 30 into a cavity 60 defined by the 
mated male and female molds 16 and 18, whereby molded articles on which 
the patterns are imprinted can be obtained. 
The operation of the air cylinder 52 and other air cylinders 106 is 
controlled by a conventional control circuit (not shown). 
When molding material is ABS, PS, PP, PE, urethane or acryl, it will not 
adhere to the pattern sheet 32. Accordingly, in this case only ink 
patterns on the pattern sheet 32 are transferred onto the surfaces of the 
molded articles or finished products. 
If the pattern sheet 32 can adhere to the surface of molded articles or 
finished products, it is punched as shown in FIG. 8, but when only an ink 
image is transferred to the molded articles or finished products, the 
pattern sheet 32 is not punched as shown in FIG. 8. 
As described above, according to the present invention, in response to the 
output signals from the detectors, the cover member 44 is moved to a 
predetermined position with respect to the pattern sheet 32. Then the 
pattern sheet 32 is sucked against the heating unit 44a of the cover 
member 44 so that the pattern sheet 32 is held while being heated. 
Thereafter, the cover member 44 is moved to a predetermined position with 
respect to the female mold 18 and the cavity of the female mold 18 is 
evacuated and the compressed air is supplied to the back of the pattern 
sheet 32 so that the pattern sheet 32 is pressed against the cavity 
surface 18a of the female mold 18. Thus, a pattern on the pattern sheet 32 
is correctly registered with the cavity surface of the female mold 18. 
The pattern sheet 32 is heated while it is sucked against the heating unit 
44a of the cover member 44. Therefore, there is no fear that the pattern 
sheet 32 is separated from the heating unit 44a of the cover member 44 and 
the pattern on the pattern sheet 32 is misaligned with respect to the 
cavity surface of the female mold 18. 
In the case of a horizontal injection molding machine in which the male and 
female molds are horizontally moved toward or away from each other while 
the pattern sheet 32 is vertically transported, the loosening of the 
pattern sheet 32 due to heating gives rise to a serious problem, but this 
problem can be substantially overcome in accordance with the present 
invention. 
Furthermore, as shown in FIGS. 9 and 10, the male and female molds may be 
so arranged that the thicknesses of the molded articles or finished 
products may be varied. That is, the cavity of a female mold 71 is deep 
and the female mold 71 is moved toward or away from a male mold 70. An 
adjusting frame 72 is fitted over the male mold 70 and is connected to the 
piston rods 74 of cylinders 73 mounted on the stationary plate 20. As a 
result, when the cylinders 73 are actuated, the frame 72 can be moved 
toward or away from the female mold 71. The leading end of the frame 72 is 
adapted to engage with the upper periphery of the female mold 71. When the 
position of the leading end of the frame 72 is suitably adjusted by 
actuating the cylinders 73, the depth of the cavity 76 of the female mold 
71; that is, the thicknesses of the molded articles or finished products 
can be adjusted. 
So far the detectors 54 have been described as detecting the X-direction 
first and then the Y-direction, but it is to be understood that they can 
simultaneously detect both the X- and Y-directions. 
So far the present invention has been described in conjunction with the 
horizontal injection molding machine, but it is to be understood that the 
present invention may be equally applied to the vertical injection molding 
machines in which the male and female molds are vertically moved toward or 
away from each other. In the latter case, the cover and frame members 44 
and 46 are moved horizontally. 
Furthermore, it is to be understood that air passages 75 may be extended 
through the side wall of the female mold 71 as shown in FIGS. 9 and 10.