Cassette-type moulding die

Abstract: A cassette-type moulding die (1) comprises a die plate unit having fitting bores (13, 14, 15, 40) and a cassette die unit including movable and stationary cassette plates (10, 52) between which a moulding cavity (55) is defined, an ejector cassette plate (11), and ejector pins (12) disposed between the movable cassette plate (10) and the ejector cassette plate (11). The cassette die unit can be detachably inserted into the fitting bores of the die plate unit. As a result, the cassette die unit can be easily changed with another cassette die unit.

Description: This invention relates to a moulding die for injection moulding resin materials or the like. More particularly, this invention relates to a cassette-type moulding die including a die plate unit having one or more cassette fitting bores and a cassette die unit capable of being detachably inserted into the fitting bores of the die plate unit. In the field of resin moulding, there has been cherished the idea such that only a core and a cavity which are essential elements in a moulding die system are designed to be separated from a moulding die frame and detachably incorporated in the moulding die frame like a cassette. Specifically, from a consideration of a current tendency to produce various kinds of moulded products in a small quantity, such a conventional moulding die system has entailed problems such as difficulty in changing the moulding die with another moulding die. Furthermore, the work for designing and producing the desired moulding die requires much time and labor and is disadvantageous from the standpoint of cost. In order to eliminate the problems described above, there have been proposed various moulding dice of a cassette type. In Japanese Patent Application Public Disclosure SHO 57-6738, a technical idea of fitting an exchangeable cassette die between a stationary die plate and a movable die plate is disclosed. Japanese Patent Publication Gazette SHO 61-53213 and Japanese Patent Application Public Disclosure SHO 60-116420 each describe a moulding die structure in which stationary and movable die plates are provided in their opposed parting face portions with fitting bores for allowing cassette die halves to be inserted therein from the fronts of the respective parting faces. Also, Japanese Patent Application Public Disclosure SHO 59-174331 teaches a moulding die device in which a separate cassette die can be detachably inserted into a moulding die unit through the upper opening formed in the moulding die unit. However, in order to fit the cassette die halves into the fitting bores formed in the stationary and movable die plates from the fronts of the parting faces of the die plates as taught by the aforementioned Japanese Patent Publication Gazette SHO 61-53213 and Japanese Patent Application Public Disclosure SHO 60-116420, the die plates must be opened wider compared with the case of normal mould opening. Therefore, the work for exchanging the cassette die consumes much time and labour. Specifically, in case that a required moulded product is large in height, it is necessary to open the die plates more widely. Thus, these facts prove to counterbalance the advantage of the cassette-type moulding die. The aforementioned shortcoming of the conventional cassette-type moulding die will be remedied by adopting a moulding die structure as proposed by Japanese Patent Application Public Disclosure SHO 59-174331. However, in this prior art structure, when one of the cassette die halves is fitted in the movable die plate, it is difficult to insert the separate movable cassette plate, ejector plate ejector pins in the movable die plate at a time, whereas the prior art makes no mention of means for effecting the work of fitting the separate elements into the die plate at a time. US-A-4,202,522 discloses a cassette-type moulding die having the features of the preamble of Claim 1. In view of the above, an object of this invention is to provide an improved cassette-type moulding die having a structure capable of uniting elements constituting a movable die in one body whilst achieving a firm location of the cassette dies in their respective die plates. The invention provides a cassette-type moulding die having the features of Claim 1. The combined movable cassette plate, ejector cassette plate and ejector pins constituting the movable cassette die can be inserted into the fitting bores of the movable die plate and ejector plate through the upper openings of the fitting bores. The movable cassette die fitted within the fitting bore of the movable die plate can easily be detached and replaced by another cassette die. Following is a description by way of example only and with reference to the accompanying drawings of methods of carrying the invention into effect. In the drawings:- Figure 1 is a vertical cross-sectional view illustrating one preferred embodiment of a cassette-type moulding die in its assembled state according to this invention. Figure 2 is a perspective view of the moulding die of Figure 1 in its disassembled state. Figure 3 is a horizontal cross-sectional view of the moulding die of Figure 1. Figure 4 is an exploded perspective view of another preferred embodiment of the moulding die according to this invention. Figure 5 is a front view of the movable die plate of the same. Figure 6 is a horizontal cross-sectional view of the same. Figures 1 through 3 illustrate one preferred embodiment of the cassette-type moulding die for resin moulding according to this invention. In the drawings, reference numeral 1 denotes a resin moulding die, 2 a movable-side retaining plate, and 3 a movable die plate. The movable die plate 3 is attached to the retaining plate 2 through spacer blocks 4 and guided slidably by tie bars 5 so that it can move backward and forward along the tie bars 5. Between the opposed spacer blocks 4, an ejector plate 6 is disposed and moved backward and forward by means of a rod 7. A stationary-side retaining plate 8 is provided with a stationary die plate 9. Between the movable die plate 3 and the ejector plate 6, there are formed fitting bores 13, 14 and 15 for detachably receiving a movable cassette plate 10, an ejector cassette plate 11 and one or more ejector pins 12 disposed between the plates 10 and 11. The fitting bores 13 to 15 have upper openings 16, 17 and 18 and are shaped in the form of a substantially U as a whole. To be more specific, the movable die plate 3 connected to the movable retaining plate 2 through the spacer blocks 4 has a parting face (3A) at the front thereof. The fitting bore 13 on the parting face (3A) side in the movable die plate 3 is wider than the fitting bore 14 on the spacer block (4) side. On the inner lateral surfaces 19 of the fitting bore 13, there are formed projecting members 22 which serve as pressure means. The rear surface 20 of the bore 13 are formed in a stepped state. The projecting members 22 are formed on a pressing seat member 24 which is fitted into dents 23 formed in the parting face and the inner lateral surface of the fitting bore 13. It is preferable that rear surfaces 25 of the projecting members 22 should be slantingly formed. Each pressure seat member 24 is located in the substantially middle portion between the upper end and the bottom of the fitting bore 13. The members 24 is detachably fixed onto the rear surfaces 25 of the dents 23 by bolts 26 in such a state that they are biased forward by springs 27. The fitting bore 15 formed in the ejector plate 6 is defined by a restraining structure comprising hook members 28 for retaining in position the ejector cassette plate 11 to be set inside the bore 15. The spacer blocks 4 are opposed to each other to form an upper opening. The aforementioned movable cassette plate 10 has a moulding core face 30 and is provided in the both side surfaces thereof with grooves 31 so as to come in engagement with the projecting members 22 formed on the inner lateral surfaces of the fitting bore 13. A rear surface 32 of the groove 31 is formed slantingly in conformity with the slant rear surface 22 of the pressure seat member 24. The movable cassette plate 10 is integrated with the ejector cassette plate 11 and the ejector pins 12 extending forward from the ejector cassette plate 11. The combined movable cassette plate 10, ejector cassette plate 11, and ejector pins 12 can readily be set in position in the fitting bores 16, 17, 18 only by being placed in the upper openings of the bores 16 - 18. When the combined plates 10, 11 and pins 12 are put onto the upper openings of the bores 16 - 18, they can easily fall into the bores with its own weight with the help of light depressing force while guiding the grooves 31 with the projecting members 22 and the ejector cassette plate 11 with the bore 15. Under the state in which lower end faces 33 of the movable cassette plate 10 and ejector cassette plate 11 come in contact with bottom walls 21, 29 of the fitting bores 13 and 15, the movable cassette plate 10 is retained in position by the inner lateral surfaces 19, rear surfaces 20 and bottom wall 21. At the time, the ejector pins 12 are apart from the inner surfaces of the bore 14 and the spacer blocks 4. Thus, the combined plates 10, 11 and pins 12 can be readily replaced by another cassette die. Similarly, a stationary cassette plate 52 can be exchanged. The stationary die plate 9 for retaining the stationry cassette plate 52 is provided with a fitting bore 40 having an upper opening 41. Within the fitting bore 40, there are formed pressure seat members 43 which are embeded in dents 44 formed in opposite inner lateral walls 48 and provided on their opposite inner surfaces with projecting members 42. The pressure seat member 43 in the dent 44 is fixed by a bolt 46. The projecting member 42 on the pressure seat member 43 may be provided with an inclined face 45. In the drawings, reference numeral 48 denotes an innermost wall surface, 50 a bottom surface, and 51 springs. The stationary cassette plate 52 to be held in the fitting bore 40 of the stationary die plate 9 is formed in a substantially rectangular shape and provided in the side edge surfaces with vertical grooves 53. When the stationary cassette plate 52 is inserted into the fitting bore 40 through the upper opening 41, it is guided by the projecting members 42 which is in engagement with the grooves 53. With this structure, the stationary cassette plate 52 can readily be set in position into the fitting bore 40 of the stationary die plate 9. In the drawings, reference numeral 54 denotes an inclined surface of the groove 53, 55 a moulding cavity, and 56 a lower surface of the stationary die plate 52. In the structure described above as one example, since the pressure seat members 24 are biased forwardly by the springs 27 so as to be elastically supported in a floating state, the movable cassette plate 10 which is placed within the bore 13 is elastically retained there without wobbling and can be readily removed from the movable die plate 3. Besides, the movable cassette plate 10 can be firmly fixed in the bore 13 by tightening the bolts 26 as required. Since the rear surfaces 25 and 32 of the projecting members 22 and the grooves 31 are slantingly formed, the engaging force produced between the opposed rear surfaces 25 and 32 can be adjusted by controlling the bolts 26. Namely, the retaining condition of the movable cassette plate 10 in the bore 13 can be freely changed. Shown in Figures 4 through 6 is another preferred embodiment of this invention. Most elements indicated by like reference symbols with respect to those of the first embodiment have analogous structures and functions to those of the first embodiment and will not be described in detail again. In this embodiment, the movable die plate comprises a pair of die plate halves 60 each formed in the shape of a substantially L. Bottom portions 61 of the die plate halves 60 are small in projected area viewed from the front. An ejector plate 62 is provided in the four corner portions thereof with receiving grooves 63 which open forward. The depth of the groove 63 is half or less as large as the thickness of the ejector plate 62. Each groove 63 is provided on the front portion thereof with a catch member 64. When the ejector plate 62 is inserted inside the movable die plate comprising the die plate halves 60 in such a state that return pins 66 are in engagement with the receiving grooves 63, there are formed relief gaps 65 between the respective return pins 66 and the die plate halves 60. In the drawings, reference numeral 67 denotes a flange portion of the return pin 66, and 78 a through hole bored in the die plate half 60 for passing the return pin 66. Furthermore, in the ejector plate 62, there is formed a trap groove 15 with stepped lug members 71 for preventing an engaging member 75 in a state inserted into the groove 15 from being out of place. The engaging members 75 are disposed on the rear surface of the movable die plate 72 and each comprise a shank 73 and a head 74. In the drawings, reference numeral 76 denotes a fitting bore defined between the spacer blocks 4, and 77 a guide pin. The cassette die constituted by the elements noted above is assembled in the following manner. When the flange portions 67 of the return pins 66 are brought into engagement with the receiving grooves 63 of the ejector plate 62, the flange portions 67 are trapped by the catch members 64 to thereby preventing the return pins 66 from moving in the axial direction thereof. At the same time, the shank potions 68 of the return pins 66 are rest on the catch members 64. As a result, the ejector plate 62 and the movable die plate 72 are united with each other. Next, the die plate halves 60 constituting the movable die plate are united to the ejector plate 62 by allowing the return pins 66 extending forward from the ejector plate 62 to be inserted into the through holes 78 bored in the die plate halves 78. Then, the die plate halves 60 which are opposite to each other to form a substantial U-shaped configuration are fixed to the movable retaining plate 2 through the spacer blocks 4. Thereafter, the movable cassette plate 10 is fitted into the fitting bore 13 in the manner described early. That is, the engaging member 75 disposed on the movable cassette plate 10 is put into the trap groove 15. Since the head 27 of the engaging member 75 is held by the stepped lug members 71, the cassette plate 10 is in no way released forwardly from the ejector plate 62. According to this embodiment, since pressure which is produced in a moulding operation and exerts to the die plate halves 60 is absorbed by the structure in which the die plate halves 60 are separated at the bottom portions 61 thereof, no deflection occurs in the die plate halves 60 and the bottom portions 61 thereof can be reduced in projected area viewed from the front. The cassette-type moulding die as a whole can therefore be minimized to some extent. Thus, by dividing the movable die plate into two halves 60, the total projected area of the bottom portions 61 could be reduced to approximately half as large as that of the bottom portion 21 in the first embodiment. Moreover, since the movable die plate is divided into the die plate halves 60, the width of the space between the die plate halves 60 can be adjusted to meet that of each of the movable cassette plates 10 having different sizes. Similarly to the die plate halves 60 of the movable die plate, the stationary die plate 9 may also be divided in two. As is clear from the foregoing description, according to this invention, the movable-side cassette die comprising the combined movable cassette plate, ejector plate and ejector pins disposed between the plates can be detachably inserted into the fitting bore in the movable die plate through the upper opening of the bore. Consequently, the movable-side cassette die can be easily set in the movable die plate as the die is in the opening state. Accordingly, the cassette die can be speedily fitted in and removed from the die plate.

Claims: A cassette-type moulding die (1) for moulding resin materials, comprising a pair of relatively movable die plates (3,9) each having a substantially U-shaped fitting bore (13,40) which has an upper opening (16,41) and is defined by lateral inner surfaces of each die plate (3,9), and a respective cassette die (10,52) which can be detachably inserted into each of said fitting bores of said first die plates (3,9) characterized in that a first, stationary die plate (9) has pressure seat members (43) embedded in said lateral inner surfaces of the stationary die plate (9), respectively, each seat member having a projecting member (42) projecting inwardly of said U-shaped fitting bore (40) in the stationary die plate (9), with a cooperating pressure receiving surface of the stationary side cassette die (52) being engaged and guided by said projecting members (42) on the pressure seat members (43) as it is fitted in the fitting bore (40) and restrained therein by said pressure seat members (43); and in that the second, movable die plate (3) has pressure seat members (24) embedded in said lateral inner surfaces of the movable die plate (3), each pressure seat member (24) having a projecting member (22) projecting inwardly of the fitting bore (13) in the movable die plate (3); and a pair of spacer blocks (4) defining a bore (15) communicating with said fitting bore (13) in the movable die plate (3), ejector plates (6) being located in said bore (15) defined by said spacer blocks (4), to receive an ejector cassette plate (11) having one or more ejector pins (12) extending therefrom, said movable-side cassette die (10) being slidably connected to said ejector plate cassette plate (11) by means of said ejector pins (12) and being detachably insertable into said fitting bore (13) in said movable die plate (3) with cooperating pressure receiving surfaces of the said movable-side cassette die (10) being engaged and guided by said projecting members (22) of said respective pressure seat members (24) which restrain the cassette die (10) in the fitting bore (13). A cassette-type moulding die according to Claim 1 wherein the pressure seat members (24,43) are resiliently biassed and have adjustable control members (26) for altering the pressure force exerted by said projecting members (22,42) on the cooperating pressure receiving surfaces of the respective cassette dies (10,52). A cassette-type moulding die according to Claim 2 wherein said undersurfaces (25,45) of said projecting members (22,42) and said cooperating surfaces (32,54) of the respective cassette dies (10,52) are inclined surfaces to facilitate adjustment of the pressure engaging force therebetween. A cassette-type moulding die according to any one of Claims 1 - 3, wherein said cassette dies (10,52) are each provided in their side surfaces with grooves (31,53) which come into engagement with the respective projecting members (22,42), when said cassette dies are inserted into said die plates (3,9), respectively. A cassette-type moulding die according to any one of Claims 1 - 4, said bores (13,15) of said movable die plate (3) communicate through a further bore (14), and said fitting bore (13) at a parting face (3A) side of the die plate (3) being wider than said further bore (14) at the spacer block (4) side of the die plate (3). A cassette-type moulding die according to any one of Claims 1 - 5, wherein said movable die plate (3) is divided at its bottom portion (61) in two halves (60) formed in a substantially L-shape.

Inventors: TAKEUCHI HIROSHI, TAKEUCHI YOSHIAKI, TAKEUCHI, HIROSHI, TAKEUCHI, YOSHIAKI
Applicants: SHINKO SELLBIC CO LTD, SHINKOH SELLBIC CO. LTD.
Application year: 1988
Main classification: B29C33
IPC codes: B29C45, B29C33