GB2263085A - Exchanging sub-moulds in injection moulding machines. - Google Patents

Abstract

Movable and fixed injection mould parts (9a, 9b) are each provided with a plurality of sub-moulds (53), which are individually automatically exchangeable at the open mould location (2) with different sub-moulds from a storage location (6), by submould carrying chucks (8) which are mounted on arms (3, 4) for rotation between positions respectively aligned with the locations (2 or 6), and for linear reciprocation at each location along axes "x" and "y" into alignment between the mould parts (9a, 9b) or sub-mould storage shelves (52), and transversely into sub-mould engaging positions with the moulds (9a, 9b) or shelves (52). The chucks may include vacuum, mechanical, oil pressure, or magnet means for holding the sub-moulds. Each sub-mould is provided with indentification means e.g. a bar code, which is identifiable by a reader means provided on the chucks, or at the storage location i.e. the shelves (52). The sub-moulds are also pre-heated at the storage location (6), by providing an oil heating circuit, or a nickel-chrome heating wire, within each shelf (52). <IMAGE>

Description

EXCHANGING SUB-MOLDS IN INJECTION MOLDING MACHINES The present invention relates to exchanging submolds in injection molding machines.

A mold for use in an injection melding machine is ordinarily provided with plural cavities in a parting line (PL) plane thereof for the purpose of producing a number of molded products.

When plural forms of a product are required to be prepared using a mold having cavities formed therein, a different mold has heretofore been prepared for each form, that is, plural molds must be prepared for producing the required forms. This causes an overall cost to be increased. In order to overcome the above disadvantage, there has been proposed a technique in which plural sub-molds each having cavities are prepared, one of the prepared sub-molds is selected in accordance with a required form and then the selected sub-mold is inserted into a common mold (common support structure).

When a sub-mold is exchanged for another one in this technique, the mold is entirely removed from a molding machine while suspending the mold with a crane or the like, and then a sub-mold accommodated in the mold is exchanged for another one.

The operation of removing the entire mold causes a significant risk because the mold itself has a heavy weight. In addition, the removing operation requires a long time and many hands, so that this operation presents an obstacle to the automation of a series of injection molding processes.

An embodiment of the present invention can provide an automatic sub-mold changer, capable of safely exchanging a sub-mold for another one in a short time and without requiring many workers, for use, for example, in an injection molding machine equipped with a pair of molds (support structures) in which sub-molds can be removably fitted. Such a sub-mold charger can facilitate the automation of a series of injection molding processes.

An automatic sub-mold changer embodying the present invention is provided in association with an injection molding machine equipped with a pair of molds in which sub-molds are detachably installed in an open state of the molds, and comprises sub-mold stock means for stocking plural sub-molds therein, and arm means having at a tip portion thereof a chuck portion to which the sub-molds are freely detachably fixed, the arm means being freely movable between a stocking portion of the sub-mold stock means and a space between the molds in the open state.

In such an automatic sub-mold changer, sub-molds used in a first molding operation are automatically removed from the mold(s) and are stocked in the stocking portion, and then new sub-molds, held in the stocking portion, for use in a second molding operation are automatically installed into the mold(s). This automatic exchanging operation of the sub-molds enables the injection molding machine to be automatically operated.

In addition, since only the sub-molds are exchanged (rather than the entire mold or molds), the exchanging apparatus itself can be miniaturized, and the exchanging operation can be safely performed.

The arm means preferably comprises a first arm for a movable-side mold and a second arm for a fixed-side mold.

Each of the sub-molds is preferably provided with identification information representing a kind (identity) thereof, and the stocking portion or the chuck portion is preferably provided with a reader for reading out the identification information. The identification information is preferably a bar code. This can prevent an incorrect kind of sub-mold from being erroneously installed into the molds and thus the sub-mold exchanging operation can be accurately performed.

The stocking portion is preferably provided with a heater for heating the sub-molds which are stocked in the stocking portion. Since the heater is provided in the stocking portion, the sub-molds are pre-heated to enable the injection molding process to start as soon as the sub-molds are installed into the molds, and thus a loss time for the injection molding process can be greatly reduced.

Reference will now be made, by way of example, to the accompanying drawings, in which: Fig. 1 is a partially exploded plan view of an automatic sub-mold changer embodying the present invention; Fig. 2 is a partially exploded side view of the automatic sub-mold changer of Fig. 1, as seen from the right-hand side in Fig. 1; Fig. 3 is a front view of guide means of the changer of Fig. 1, which is viewed from the right-hand side in Fig. 2; Fig. 4 is a perspective view of sub-mold stock means of the Fig. 1 changer; Fig. 5 is a side perspective view of a sub-mold for use with the changer of Fig. 1, which view also shows a sub-mold holding state of a hold spring included in the stock means of Fig. 4; Fig. 6 is an underside perspective view of the submold of Fig. 5; Fig. 7 is a plan view of the sub-mold stock means, and Fig. 8 is a side view of parts of the changer of Fig.

1 for illustrating operation thereof.

As shown in Figs. 1 and 2, an automatic sub-mold changer 1 is provided adjacent to an injection molding machine 2. The automatic sub-mold changer 1 is provided adjacent to an injection molding machine 2. The automatic sub-mold changer 1 comprises arm means 5 including a first arm 3 and a second arm 4 which are rotatable and movable in a left-and-right direction and an up-and-down direction of Fig. 1 (hereinafter referred to as "x-direction and y-direction", respectively), stock means of sub-mold (sub-mold stock means) 6 which is movable in the x- and y-directions, and guide means 7 as described later. The first and second arms 3 and 4 are provided with chucks 8 at tip portions thereof, respectively.

In the automatic sub-mold changer thus constructed, an exchange operation of changeable sub-molds is performed as follows. Changeable sub-molds which are freely detachably installed in a movable-side mold 9a and a fixed-side mold 9b are adsorbed by the chucks 8 (detachably fixed to the chucks by air suction), and then carried to and stocked in the sub-mold stock means 6.

Thereafter, other changeable sub-molds which are stocked in the stock means 8 are adsorbed by the chucks 8 (detachably fixed to the chucks 8 by air suction), and then carried to and fixedly installed into the movableside and fixed-side molds 9a and 9b. Since the arms 3 and 4 are unstably supported at one side thereof (that is, cantilevered) when moved frontwards (that is, downwardly in Fig. 1), the guide means 7 serves to stably support the arms 3 and 4.

Each of the movable-side mold 9a and the fixed-side mold 9b is provided with hollows (recesses) for sub-molds (not shown), extending inwardly in a direction perpendicular to the PL (parting line) plane, into which four changeable sub-molds are insertable (hereinafter referred to as "sub-mold hollows"). In order to fixedly secure the inserted changeable sub-molds into the movable-side and fixed side molds 9a and 9b, engaging keys (not shown) which are used to fixedly secure the changeable sub-molds to the sub-mold hollows through the engagement with the sub-molds are also provided in such a manner as to be inserted into key grooves which are formed in parallel to the PL planes of the movable-side and fixed side molds 9a and 9b.

The arm means will be hereunder described in more detail.

In Fig. 2, the arm means 5 is mounted on a rotary table 11, and the rotary table 11 is rotatably and pivotally supported by a fixed table 13 which is fixed to a fixed mount table 12. The rotary table 11 is rotated through a coupling 15 by a rotary actuator 14 which is secured to the fixed table 13. The fixed table 13 is designed so as to extend to a left side of Fig. 1 where the stock means 6 is disposed.

A pair of rails 17 each extending in the x-direction of Fig. 1 are provided on the rotary table 11 while a pair of guides 19 are fixedly secured to a lower surface of a support table for arm means (hereinafter referred to as "arm support table 16"), and the rails 17 and the guides 19 are engaged through a slide bearing 18, whereby the arm support table 16 is slidably moved in the xdirection in Fig. 1 along the rails 17.

A pair of support poles 21 are projectingly provided at left and right side positions on the rotary table 11 as shown in Fig. 1, and a cylinder 22 is provided suspensively between the top ends of the poles 21. In addition, a guide plate 23 which is sandwiched between the arms 3 and 4 is fixedly secured to a slider 25 through a coupling member 24. The cylinder 22 serves as a rodless cylinder for driving the slider 25. That is, the cylinder 22 has a hollow or cavity structure extending in an axial direction thereof, and a part of the slider 25 is inserted into the cavity of the cylinder 22. The slider 25 is slidably moved along the cylinder 22 by blowing air against the inserted part of the slider 25 within the cavity, or in any other suitable manner.

The rodless cylinder 22 enables the guide plate 23 to be moved in the x-direction as shown in Fig. 1, and thus enables the arms 3 and 4 sandwiching the guide plate 23 to be moved in the x-direction interlockingly with the movement of the guide plate 23. As described later, the arms 3 and 4 are unmovable in the x-direction relatively to the arm support table 16, and thus the arm support table 16 is also moved along the rail 17 interlockingly with the movement of the arms 3 and 4, that is, with the driving of the rodless cylinder 22. The guide plate 23 is sandwiched by the arms 3 and 4 through protection plates 41 as described later, whereby the arms 3 and 4 are protected from being damaged.

A pair of cylinders 26 each extending in the ydirection as shown in Fig. 1 (in the left-and-right direction in Fig. 2) are fixedly secured onto the arm support table 16, and sliders 27 which are secured to the arms 3 and 4 are engaged with the cylinders 26. Like the cylinder 22, the cylinders 26 serve as rodless cylinders for driving the sliders 27. A holder 28 having a Tshaped section on a plane which is vertical to the drawing and parallel to the x-direction is fixedly provided on the arm support table 16 at a lower side of the rotary table 11 in Fig. -1, and guides 31 are secured to both sides of an upper plate of the holder 28. The guide 31 is freely slidably engaged with rails 3a and 4a which are provided at upper portions of the arms 3 and 4, respectively.As described above, the arms 3 and 4 are slidably moved in the y-direction as shown in Fig. 1 by a driving force of the rodless cylinder 26 while guided by the guide 31.

Four chucks 8 are provided at the outside of the tip portion of each of the arms 3 and 4. Each chuck 8 is provided with a pair of air section ports 8a as shown in Fig. 2 at upper and lower portions thereof. Each of the air suction ports 8a is coupled through a pipe (not shown) to a vacuum pump (not shown). Therefore, air is sucked through the air suction prot 8a by actuating the vacuum pump, and sub-molds which are in contact with the chucks are adsorbed by the air sucking force. Each of the chucks 8 is provided with a pair of positioning pins 8b at symmetrical corners thereof.

Next, the guide means 7 will be described in more detail.

A mount table 32 is integrally secured to the injection molding machine 2 as shown in Fig. 2, and a cylinder 33 and a rail 34 are secured onto the mount table 32 along an opening-and-closing direction of the molds as shown in Fig. 1. As shown in Figs. 2 and 3, a slider 38 and a guide 39 are secured to a U-shaped guide member 35 through coupling members 36 and 37, and the slider 38 and the guide 39 are engaged with the cylinder 33 and the rail 34, respectively. The cylinder 33 serves as a rodless cylinder for driving the slider 38, and thus the guide member 35 is slidably movable in the opening and closing direction of the molds along the rail 34 by a driving force of the rodless cylinder 33.

At the inner surfaces of the upper and lower portions of the guide member 35 are formed guide grooves 35a and 35b Any one of the arms 3 and 4 is inserted into the grooves 35a and 35b and supported at this inserting position. Further, the protection plates 41 are provided at the upper and lower end portions of both surfaces of the arms 3 and 4, and the arms 3 and 4 are supported through the protection plates 41 in the guide grooves 35a and 35b as shown in Fig. 8.

Next, the sub-mold stock means 6 will be described hereunder.

As described above, the sub-mold stock means 6 is disposed at the left side of the fixed table 13. In this embodiment, a line connecting the rotational axis of the rotary table 11 and the molds 9a and 9b and another line connecting the rotational axis of the rotary table 11 and the sub-mold stock means 6 are set to be intersected at substantially 900.

The sub-mold stock means 6 includes two tables, an x-table and a y-table which are disposed at upper and lower portions of the stock means 6 and movable in the xdirection and y-direction, respectively. A cylinder 44 and a rail 43 are fixed in the x-direction at a left portion of the fixed table 13, and a slider 45 and a guide (not shown) which are engaged with the cylinder 42 and the rail 43 respectively are fixed at the lower surface of the x-table 44. The cylinder 42 serves as a rodless cylinder for driving the slider 45, and the xtable is slidable in the x-direction along the rail 43 by a driving force of the rodless cylinder 42.Further, a rodless cylinder 46 and a rail 47 are likewisely fixed in the y-direction on the upper surface of the x-table 44, and a cylinder 49 and a guide (not shown) which are engaged with the rodless cylinder 46 and the rail 47 respectively are fixed at the lower surface of the ytable 48. The y-table is movable in the y-direction along the rail 47.

Four poles 51 are projectingly provided at the four corners of the y-table 48 as shown in Fig. 4, and a three-stage shelf assembly comprising three shelf plates 52 which are arranged in a vertical direction of Fig. 4 is suspensively provided between each pair of neighbouring poles which are confronted to each other in a direction vertical to a longitudinal direction of the y-table 48. The upper and lower spaces defined between the respective shelf plates 52 of each three-stage shelf assembly serve as upper and lower sub-mold stocking portions each having stock capability of stocking four changeable sub-molds.

As shown in Figs. 5 and 6, each changeable sub-mold 53 has a flange portion 53b on the front surface of a body 53a thereof. A pair of positioning holes 53c are formed at two corners which are diagonally confronted to each other on the flange portion 53b. In correspondence to this arrangement of the sub-mold .53, a shoulder portion 52a for accommodating the flange portion 53b of the sub-mold 53 is provided on each shelf plate 52, and a positioning pin 52b is provided on the shoulder portion 52a. In order to prevent the sub-mold 53 from falling off from the shelf plate 52, a hold spring 54 is provided at a position between respective neighbouring sub-molds to be accommodated on the shelf plate 52.As shown in Fig. 5, the hold spring 54 is formed by bending a plate spring, and is so designed that the body portion 53a of the sub-mold 53 is supported by respective one end portions of a pair of hold springs 54. No hold spring 54 is provided at either end portion of each shelf plate 52 because a sub-mold positioned at such an end portion will be supported on one side thereof by one of the poles 51.

As shown in Fig. 6, a bar code 55 is attached to the bottom surface of the sub-mold 53, and a glass window 52c is provided at a position on each shelf plate 52 whore the bar code 55 is located when the sub-mold 53 is accommodated in a space between the shelf plates 53. A bar code reader for reading out the bar code of each submold is provided within each glass window 52c, and the identity of the sub-mold is detected on the basis of the read-out bar code.

As shown in Fig. 7, an oil passageway 52d (a passageway of oil) is provided within each shelf plate 52 to circulate oil in the whole portion of the shelf plate 52, and tubes 56 are secured to the inlet and outlet of the oil passageway 52d. The tubes 56 of the respective shelf plates 52 of the three-stage shelf assembly are connected to one another, and finally connected to an oil heater (not shown). Therefore, the shelf plates 52 are heated by circulating the heated oil through the oil passageways 52d of the shelf plates 52.

An operation of the automatic sub-mold changer of Figs. 1 to 7 will be next described.

The following description is made in a case where a manufacturing process using one set (kind) of sub-molds is completed, and a manufacturing process using another set of sub-molds is to be carried out.

First, in response to an instruction of a CPU of the automatic sub-mold changer, the arm support table 16 and the guide member 35 of the guide means 7 are moved in the x-direction as shown in Fig. 1 and stopped at a predetermined position in order to remove sub-molds which are installed, for example, in the fixed-side mold 9b.

Thereafter, the second arm 4 located at the right side in Fig. 1 is driven to travel forwards (to be moved downwardly in Fig. 1) slidably along the grooves 35a and 35b, and stopped at a position, between the molds 9a and 9b, in which the chucks 8 are opposed to the sub-molds in the fixed-side mold 9b as shown in Fig. 8. The arm support table 16 and the guide member 35 are interlockingly moved in the right direction in Fig. 1, and stopped at a position where the positioning pins 8b of the chucks 8 are engaged with the positioning holes 53c of the sub-molds.

Next, the key is pulled out of the key grooves by an air cylinder (not shown), and at the same time the vacuum pump is actuated to attach the four sub-molds to the respective chucks 8 by air suction. Thereafter, the arm support table 16 and the guide member 35 are interlockingly moved in the left direction in Fig. 1 to remove the sub-molds from the sub-mold hollows (recesses), and then the arm 4 is driven to travel backwards (to be moved upwardly in Fig. 1). Next, in order to remove the sub-molds from the movable-side mold 9a, in the same manner as described above, the first arm 3 is driven to travel forwards (to be moved downwardly in Fig. 1) while supported by the guide member 35, and then is leftwardly moved to fix the four sub-molds of the movable-side mold 9a to the chucks by air suction.

Thereafter, the first arm 3 is driven to travel backwards (to be moved upwardly in Fig. 1).

Next, the rotary table 11 is rotated in the clockwise direction (in Fig. 1) through 90 by actuation of the rotary actuator 14, whereby the arms 3 and 4 are driven so as to be oriented in the x-direction.

Thereafter, the arms 3 and 4 are driven to go forward (to be moved in the left direction in Fig. 1) to a position where the chucks 8 are opposed to vacant positions of the sub-mold stock means 6 (for example, two rows at the left side), and the movement of the arms 3 and 4 in the xdirection is ceased. Next, the arm support table 16 is moved, for example, in the y-direction (upwardly in Fig.

1), and the positioning holes 53c are engaged with the positioning pins 52b, whereby the sub-molds are accurately inserted (stocked) in the corresponding stock spaces. Each of the stocked sub-molds are supported at both ends thereof by the hold springs 54, and then the air suction is ceased. Thereafter, the arm support table 16 is moved in the y-direction (downwardly in Fig. 1), and at the same time the sub-molds attached to the arm 4 are stocked in the corresponding stock spaces.

Next, the arm support table 16 goes back slightly (is slightly moved in the right direction in Fig. 1) so that the arms 3 and 4 are moved to the right side in the x-direction, and stopped at a position where the chucks 8 are opposite two rows on the right-hand side, at which sub-molds are stocked. Thereafter, the arm support table 16 is moved in the y-direction (downwardly in Fig. 1) so as to engage the positioning pins 8b of the chucks 8 with the positioning holes 53c of the new sub-molds, and the sub-molds are fixed to the chucks by air suction.In this case, the sub-molds are provided with bar codes 55, and the identities of the sub-molds to be next installed in the injection molding machine are confirmed beforehand by reading out the bar codes thereof on the basis of the instruction of the CPU using the bar code reader, so that the desired sub-molds are surely adsorbed by the arms 4.

Thereafter, the arm support table 16 is moved in the ydirection (upwardly in Fig. 1) to fix the sub-molds to the arm 3 by air suction in the same manner as described above. When the sub-molds are fixed to both of the arms 3 and 4, the arm support table 16 goes back slightly (is slightly moved in the x-direction (to the right in Fig.

1)), the arms 3 and 4 travel back (are moved to the right, in the x-direction), and then the rotary table 11 is rotated in the counterclockwise direction through 90 In reverse order to that of the sub-mold removing process, the sub-molds attached to the arms 3 and 4 are installed into the movable-side mold 9a and the fixedside mold 9b, and the arms 3 and 4 are installed into the movable-side mold 9a and the fixed-side mold 9b, and the arms 3 and 4 are driven to go back. By these operations, the sub-mold exchanging operation is completed.

The sub-molds are pre-heated through thermal conduction by the heated shelf plates 52, and thus an injection molding process can be started substantially immediately upon completion of the sub-mold exchanging operation.

In a sub-mold changer embodying the present invention because only the sub-molds need be exchanged, material having high mechanical strength, which must be used when the entire mold is required to be supported, is not required for the arms 3 and 4 and other elements of the changer because these arms 3 and 4 are used to support only the sub-molds. Therefore, the sub-mold changer can be miniaturized, and an operating performance thereof can be improved. Further, since the first and second arms 3 and 4 are provided at the tip portions thereof with the chucks whose number is equal to that of the sub-molds of the molds 9a and 9b and which have the same arrangement as the sub-molds of the molds 9a and 9b, the sub-molds can be simultaneously attached to or detached from the mold 9a or 9b through one contacting or detaching operation of the arms 3 and 4, as the case may be, so that the time required for the sub-mold exchanging operation can be shortened.

In the sub-mold exchanging operation of the above embodiment, the x-table and y-table of the sub-mold stock means are not moved. However, after the arms 3 and 4 have been rotated in the clockwise direction through 900 the x-table 44 and the y-table 48 may be moved to bring the chucks towards the stock means. Alternatively, after the arms 3 and 4 have been so rotated, all of the x-table 44, the y-table 48 and the arms 3 and 4 may be moved to bring the chucks 8 towards the stock means.

Further, in the above embodiment, the guide means 7 is secured to the injection molding machine 2, however, it may be secured to the fixed table 13 or the like.

The sub-mold changer of the above embodiment is so designed that the sub-molds are held by the chucks through air suction, however, the sub-molds may be held by the chucks through various means such as a mechanical chuck, oil pressure, magnet and so on.

In the above embodiment, the heated oil which is circulated in the shelf plates 52 is used as a heater.

However, other heating means may be adopted. For example, a nickel-chrome wire may be embedded into each shelf plate 52 and current caused to flow into the nickel-chrome wire to heat the shelf plate 52.

Further, in the above embodiment, the bar code reader is provided in the stock means. However, the bar code reader may be provided on the chucks 8 and designed so as to read out the bar codes of the sub-molds when the chucks 8 approach to the sub-molds. The position where the bar code is provided is not limited to the above embodiment, and may be any position such as the flange portion of the sub-mold or the back surface of the submold. In this case, the bar code reader may be disposed in the sub-mold stock means, being of the built-in type, or may be a separate member capable of scanning the bar code. Also, the bar code is used as identification information for sub-molds in the above embodiment. In place of the bar code, different marks may be assigned to different kinds of sub-molds and read out by a photosensor or the like.Any suitable kinds of identification information and reading means may be adopted.

Still further, in the above embodiment, the sub-mold is inserted or detached by being moved in a direction perpendicular to the PL plane of the mold. However, this invention is applicable to a case where the sub-mold is inserted or detached in a parallel direction to the PL plane.

Thus, as described hereinbefore, in use of an embodiment of the invention the chuck portion, which is provided at the tip portion of the arm means, is inserted in a space between a pair of molds in an open state, and holds the sub-molds. Thereafter, the arm means is moved to shift the chuck portion to the stocking portion of the sub-mold stock means so that the sub-molds are stocked in the stocking portion. Next, other sub-molds stocked in the stocking portion are held by the chuck portion, and carried to the space between the molds by the arm means to fixedly install the sub-molds into the molds.

The arm means may comprise a first arm for the movable-side mold and a second arm for the fixed-side mold, and thus the sub-molds in the movable-side mold and the sub-molds in the fixed-side mold can be individually held by the different arms. Accordingly, even in a case where the space between the molds is narrow, the sub-mold exchanging operation can be easily performed by inserting one of the arms into the space after the other arm holding the sub-molds in one of the molds is moved away from the space.

Further, each of the sub-molds may be provided with identification information representing the identity thereof, so that an erroneous exchanging operation can be completely prevented by detecting the identification information of sub-molds to be next used.

Still further, the stocking portion may be provided with a heater to preheat the sub-molds which are stocked in the stocking portion. Therefore, a time for heating the sub-molds once installed into the molds is not required and thus the injection molding process can be started immediately after the sub-molds are installed into the molds.

Claims (6)

1. An injection molding process employing a mold support assembly comprising a first support structure provided at a main face thereof with means for receiving, at respective different predetermined locations, a plurality of removable mold devices formed with respective molding surface portions which, when the assembly is in use, face away from the said support structure towards a second support structure of the assembly, one of the first and second support structures being movable towards the other to bring about closure of respective mold cavities bounded by the said molding surface portions, in which process:: a first molding operation is performed by securing a first such plurality of removable mold devices to the said first support structure at the said respective different predetermined locations when the first and second support structures are in a spaced-apart state, moving the two support structures together to bring about such closure of the said respective mold cavities, and introducing molding material into those cavities, whereafter molded products are removed from the said assembly with the said first and second support structures in the said spaced-apart state; and a second such molding operation is then performed after replacing one of the said mold devices of the said first plurality, at its said predetermined location on the said first support structure, by a further mold device, formed with a molding surface portion different from that of the replaced mold device.

2. An automatic sub-mold changer for use in an injection molding machine equipped with a pair of molds in which sub-molds are detachably installed in an open state of the molds, comprising: sub-mold stock means for stocking plural sub-molds therein; and arm means having at a tip portion thereof a chuck portion to which said sub-molds are freely detachably fixed, said arm means being freely movable between a stocking portion of said sub-mold stock means and a space between said molds in the open state.

3. The automatic sub-mold changer as claimed in claim 2, wherein said arm means comprises a first arm for a movable-side mold and a second arm for a fixed-side mold.

4. The automatic sub-mold changer as claimed in any one of claims 2 and 3, wherein each of said sub-molds is provided with identification information representing a kind thereof, and wherein said stocking portion or said chuck portion is provided with a reader for reading out the identification information.

5. The automatic sub-mold changer as claimed in claim 4, wherein said identification information is a bar code.

6. The automatic sub-mold changer as claimed in any one of claims 2 to 5, wherein said stocking portion is provided with a heater for heating sub-molds which are stocked in said stocking portion.