Patent Application
20060170135
1. Field of the Invention
The present invention relates to a method and a molding machine for manufacturing resin molded products and, more particularly, to a method and a molding machine for molding plural kinds of molded products having different shapes by changing the shape of a product portion in a mold.
2. Description of the Related Art
As a prior art, there is a resin molding machine disclosed in, for example, Patent document 1 described below. Using the molding machine according to this prior art, it is possible to mold plural kinds of molded products from one mold by sliding a nest comprising plural dies corresponding to the shapes of plural kinds of molded products to replace part of a product portion of the mold with another.
In the case of this molding machine, when the number of times of molding of a first kind of molded product reaches a predetermined number, the operation of the molding machine is stopped and part of the product portion is replaced with a different die so as to fit to the product portion by sliding the nest. Next, the molding machine is restarted and a kind of molded product different from the first kind is molded.
However, in the case of the molding machine according to the above-mentioned prior art, when the shape of a molded product to be molded is changed, the operation of the molding machine is stopped while the shape of a resin filled region of the product portion is changed by sliding and moving the nest. In other words, after a molding cycle for the first kind of molded product is put to rest, the nest is moved so as to correspond to the shape of a molded product to be molded next and then a molding cycle for the next kind of molded product is started to mold a molded product with a changed shape.
Therefore, when the frequency of changes in shape of molded products increases, there arises a problem that the ratio of time during which. the molding cycle is not operated increases and the productivity is reduced.
The above-mentioned problem being taken into account, the present invention has been developed and an object thereof is to provide a method for manufacturing molded products and a molding machine capable of preventing a productivity from decreasing even if the frequency of changes in shapes of molded products increases.
In order to attain the above-mentioned object, a molding method for manufacturing molded products according to a first aspect of the present invention comprises:
a molding cycle, which is a collection of processes to be performed sequentially, including, a filling process for filling molten resin into a product portion (30) of a mold (1) by injecting it, a cooling and solidifying process for cooling down and solidifying the molten resin in the product portion (30) filled in the filling process, a mold opening process for opening the mold (1), a taking-out process for taking out the solidified molded product from the product portion (30) of the opened mold (1), and a mold closing process for closing the mold (1); and
a product portion shape changing process for changing a shape of a molten resin filled region (31) in the filling process of the product portion (30) in accordance with plural kinds of molded products having different shapes; wherein the plural kinds of the molded products having different shapes are molded by repeating the molding cycle plural times while performing the product portion shape changing process; and wherein during one molding cycle (SA) of the plural-time molding cycles, the product portion shape changing process is performed in accordance with the shape of a molded product (B) to be molded in a next molding cycle (SB) following the one molding cycle (SA).
According to this, even when the shapes of the molded products (A, B) are changed, the shape of the product portion (30) is changed in accordance with the shape of the molded product (B) to be molded in the next molding cycle (SB) during the present one molding cycle (SA) and, therefore, it is not necessary to stop the molding cycle. As a result, even if the frequency of changes in shape of molded products (A, B) increases, it is possible to prevent the productivity from decreasing.
Further, as in a molding method according to a second aspect of the present invention, the product portion shape changing process in accordance with the shape of the molded product (B) to be molded in the next molding cycle (SB) can be performed during the period after the resin is cooled down and is solidified in the cooling and solidifying process until the mold closing process is completed in the one molding cycle (SA).
A molding method according to a third aspect of the present invention is characterized in that:
a partition member (16) provided in the mold (1) is moved to switch between a state in which part of the production portion (30) is isolated and a not-isolated state, in which part of the production portion (30) is not isolated, in the product portion shape changing process; in that
the plural-time molding cycles comprise a first molding cycle (SA) in which filling of molten resin into the part of the product portion (30) is shut off by the partition member (16) in the filling process and a second molding cycle (SB) in which the shut-off by the partition member (16) is not performed and filling of molten resin into the part of the product portion (30) is performed in the filling process; and in that
the plural kinds of molded products having different shapes are molded in the plural-time molding cycles.
According to this, it is possible to easily change the shape of the molten resin filled region (31) by isolating or not isolating the part of the product portion (30) by the partition member (16). Therefore, it is easy to change the shape of the product portion (30) in accordance with the plural kinds of molded products (A, B).
A molding method according to a fourth aspect of the present invention is characterized in that in a case in which the shape of the molten resin filled region (31) is changed in the product portion shape changing process, a portion forming a molten resin not-filled region (32) of the product portion (30) is heated to a temperature higher than the dew point of the atmosphere surrounding the mold, in the filling process.
According to this, even if the atmosphere surrounding the mold flows, when the mold is opened, into the portion to be the molten resin not-filled region (32) of the product portion (30) that is not filled with molten resin in the filling process and therefore is likely to be readily cooled down, water condensation does not occur. Therefore, even when the molding cycle (SA) is entered, in which the region (32) is filled with molten resin, it is possible to obtain a molded product (A) excellent in quality.
A molding method according to a fifth aspect of the present invention is characterized in that:
the mold (1) has a heat insulated space (15), in which supply paths (13, 14) are formed for supplying molten resin to the product portion (30) in the filling process and at the same time, a heating path forming member (12) is possessed for preventing solidification of the molten resin in the supply paths (13, 14) until the filling process of the next molding cycle (SB); and
that the portion to be the molten resin not-filled region (32) of the product portion (30) in the filling process is communicated with the heat insulated space (15) and the portion to be the molten resin not-filled region (32) is heated to a temperature higher than the dew point of the atmosphere on the periphery of the mold.
According to this, it is possible to prevent water condensation at the portion forming the molten resin not-filled region (32) of the product portion (30) in the filling process by utilizing the heat of the heating path forming member (12) for preventing solidification of the molten resin in the supply paths (13, 14).
A molding method according to a sixth aspect. of the present invention is characterized in that the product portion shape changing process comprises a shape changing member (16) provided in the mold (1) to change the shape of the molten resin filled region (31) of the product portion (30) and a shape changing member moving means (17) for moving the shape changing member (16), and controls the movement of the shape changing member moving means (17) in accordance with the shapes of the molded products (A, B) to be molded.
A molding method according to a seventh aspect of the present invention is characterized in that the shape changing member (16) is the partition member.(16) for switching between a state in which part of the product portion (30) is isolated and a not-isolated state in which part of the product portion (30) is not isolated.
According to this, it is easy to change the shape of the product portion (30) in accordance with the plural kinds of the molded products (A, B).
A molding method according to an eighth aspect of the present invention is characterized in that the heating of the portion forming a molten resin not-filled region (32) is performed with heating means (12, 15, 18, 19), the heating means: comprising:
a heat insulated space (15) formed inside the mold;
a heating path forming member (12) formed inside the heat insulated space (15) to form supply paths (13, 14) for supplying molten resin to the product portion (30) and to prevent solidification of the molten resin in the supply paths (13, 14);
a communication path (18) provided inside the mold (1) to communicate the product portion (30) with the heat insulated space (15);
and an open/close means (19) for opening and closing the communication path (18).; and in that
the open/close means (19) is controlled to operate so that the portion forming the molten resin not-filled region (32) of the product portion (30) is communicated with the heat insulated space (15) when molten resin is injected to the product portion (30) to fill it therewith.
According to this, it is possible to prevent water condensation at the portion forming the molten resin not-filled region (32) of the product portion (30) in the filling process by utilizing heat of the heating path forming member (12) for preventing solidification of the molten resin in the supply paths (13, 14).
The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.
In the drawings:
Embodiments of the present invention are explained below with reference to drawings.
As shown in
As shown in.
In the fixed die 10, a cavity portion 10a forming a recess shape toward the movable die 20 side is formed and in the movable die 20, a core portion 20a forming a protruding shape toward the fixed die 10 side is formed. Then, when the fixed die 10 and the movable die 20 meet together (mold clamping or closing), a space is formed between the cavity portion 10a of the fixed die 10 and the core portion 20a of the movable die 20. This space is a product portion 30 for molding the molded products A and B.
In the fixed die 10, a sprue 13 and a runner 14 forming a supply path of molten resin to the product portion 30 are formed. The sprue 13 and the runner 14 are formed in a manifold 12 so as to keep the temperature of the molten resin in the supply path and to prevent solidification of the molten resin in the supply path. The manifold 12 constitutes a so-called hot runner having a heating means and is arranged in an arrangement space 15 formed as a heat insulating space in the fixed die 10.
The fixed die 10 incorporates a partition plate 16, which is a partition member, and a hydraulic cylinder 17 for moving forward and back the partition plate 16 into and from the product portion 30.
As shown enlargedly in
On the other hand, as shown enlargedly in
In other words, the partition plate 16 is a shape changing member in the present embodiment, which changes the shape of the molten resin filled region 31 of the product portion 30 by switching between a state in which part of the product portion 30 is isolated and a not-isolated state, and the hydraulic cylinder 17 is a shape changing member moving means in the present embodiment.
Specifically, as shown in FIGS. 8 (a) and 8 (b), an inclined rod 17a of the hydraulic cylinder 17 runs through a through hole 16a provided in the partition plate 16 and the movement of the partition plate 16 by the hydraulic cylinder 17 is carried out as the inclined rod 17a advances and retracts.
As shown in
A control unit 50 controls operation of the mold clamping (closing) unit comprising the injection unit 40 and the mold 1.
The control unit 50 is designed so as to output signals to the mold clamping unit mounting the injection unit 40 and the mold 1 so that a well-known molding cycle is performed sequentially and a molten resin is injected to fill the product portion 30 of the mold 1 by the injection unit 40, the mold 1 is opened after the molten resin filled in the product portion 30 is cooled down and is solidified, the solidified molded products A and B are taken out from the product portion 30 of the opened mold 1, and the mold 1 is closed, as well as receiving operation completion signals and data signals from the mold clamping unit and the injection unit 40.
On the other hand, a nesting control unit 60 is designed so as to output operation signals to the hydraulic cylinder 17 incorporated in the mold 1 as well as receiving operation completion signals from the hydraulic cylinder 17.
The control unit 50 internally comprises a count/storage section 51, which is a count means and a storage means, and is designed so as to be capable of storing the molding conditions, the number of times of molding, and the order of molding of the molded products A and B input from an input device 70, which is an input means, as well as grasping the number of times of molding of each molded product and the progress status of molding cycle based on the signals from the injection unit 40 and the mold 1 (actually, the mold clamping unit).
On the other hand, the nesting control unit 60 internally comprises a.count/storage means 61, which is a count means and a storage means and is, as in the control unit 50, designed so as to capable of storing the number of times of molding and the order of molding of the molded products A and B input from the input device 70 as well as grasping the operation status of the hydraulic cylinder 17 while judging the number of times of molding of each molded product and the progress status of the molding cycle based on information from the control unit 50.
Further, the control unit 50 is designed so as to be capable of grasping the operation status of the hydraulic cylinder 17 based on information from the nesting control unit 60. The control unit 50 and the nesting control unit 60 are control means in the present embodiment.
The input device 70 may be one that sequentially inputs information of the order of manufacture of the molded products A and B or one that inputs, in a batch, a collection of information of production plans etc.
Further, the input device 70 is designed so as to output correction information input from a correction input device 71 to both the control units 50 and 60. Due to this, it is made possible to correct a difference between the number of molding cycles and the number of manufactured molded products, which occurs owing to molding defects etc.
Next, a method for manufacturing a molded product by the molding machine having the above-mentioned configuration is explained.
When the control unit 50 shown in
When the molten resin filled in the product portion 30 is cooled.down and is solidified, and the molded product is molded, the fixed die 10 and the movable die 20 are opened as shown in
When the molded product A is taken out from the mold 1, the fixed die 1O and the movable die 20 meet with each other to close the mold 1 as shown in
Here, the process shown in
In contrast to this, when the molded product B is molded, before the filling process is initiated, part of the product portion 30 is isolated by the partition plate 16 and the shape of the molten resin filled region 31 of the product portion 30 is made to correspond to the molded product B, as shown in
Here, an operation is explained when the molding cycle of the molding machine in the present embodiment is switched from a molding cycle SA for molding the molded product A to a molding cycle SB for molding the molded product B.
When the molding cycle SA is performed by the control of the control unit 50 of the molding machine, in the mold 1, the filling process, the cooling process, the mold opening process, the taking-out process, and the mold closing process are performed sequentially, as described above.
During the period of taking-out the molded product A from the mold 1, the hydraulic cylinder 17 is operated by the control of the nesting control unit 60 of the molding machine such that the partition plate 16 is. moved to shut off the product portion 30 to isolate a part thereof. Due to this, the shape of the molten resin filled region 31 in accordance with the filling process in the next molding cycle SB is formed.
On the other hand, in the injection unit 40, the injecting process (injecting operation and pressure maintaining operation) for injecting the molten resin to fill the product portion 30 of the mold 1 in the filling process is performed, and when the injecting process is completed, a measuring process of the molten resin for the injecting process of the next molding cycle SB is performed.
As described above, when the molding cycle SA and the molding cycle SB are performed continuously, during one molding cycle SA, the entire switching operation to prepare for the next molding cycle SB is performed.
Specifically, by the time of the completion of the injecting process (by the time of the completion of the filling process) in the molding cycle SA by the injection unit 40, directions are given for measuring the amount of the molten resin in accordance with the amount of injection and filling in the next molding cycle SB by the control unit 40. Further, by the time of the start of the injecting process (by the time of the start of the filling process) in the next molding cycle SB, directions are given as to the injection pattern (molding conditions) in the molding cycle SB by the control unit 40.
On the other hand, during the period of the taking-out process, in the mold 1, directions are give as to the operation of the hydraulic cylinder 17 by the nesting control unit 60, whereby the shape of the molten resin filled region 31 of the product portion 30 is changed by the partition plate 16. It is only necessary to change the shape of the molten resin filled region after the mold opening process is started and by the time of completion of the mold closing process (before. the filling process of the next molding cycle SB is started) in the molding cycle SA. Due to this, it is possible to move the partition plate 16 without interfering with the molded product A.
Although the operation when the molding cycle of the molding machine is switched from the molding cycle SA for molding the molded product A to the molding cycle SB for molding the molded product B is described here, the operation when the molding cycle SB is switched to the molding cycle SA is performed in the same manner.
However, when switching from the molding cycle SB to the molding cycle SA, it is only necessary to change the shape of the molten resin filled region after the molten resin is cooled down and is solidified (after the resin in contact with the partition plate 16 is solidified and becomes difficult to be changed in shape) in the cooling process in the molding cycle SB and before the mold closing process is completed (before the filling process in the next molding cycle SA is started).
According to the configuration and operation described above, when the shape of the molded product to be molded in the next molding cycle is changed from the shape of the molded product to be molded in the present molding cycle (before the next molding cycle, described above), the shape changing process of the molten resin filled region 31 of the product portion 30 is performed in accordance with the shape of the molded product to be molded in the next molding cycle during the present one molding cycle.
Consequently, it is not necessary to stop the molding cycle in order to change the shapes of the molded products A and B. Therefore, even if the frequency of changes in shape of the molded products A and B increases, it is possible to prevent the productivity from decreasing.
For example, when A to B to A to A to B to B to A is input as an order of molding of molded products from the input device 70 shown in
In contrast to this, in the prior art, it is possible to increase the productivity of plural kinds of molded products having different shapes by molding the products having the same shape continuously to reduce the number of times of nest movement. However, when molding is performed in an order other than the required order of different molded products in after processes, it is necessary to store molded products between the molding process and the after processes.
In the present embodiment, it is easy to save a storage space of molded products because molding of various molded products can be performed in a specific order in accordance with the required order of different molded products in the after processes.
Further, by only switching between the state in which part of the product portion 30 is isolated and the not-isolated state using the partition plate 16, the shape of the molten resin filled region 31 can be changed easily. Therefore, it is possible to quickly and easily change the shape of the product portions 30 in accordance with the plural kinds of products A and B.
Next, a second embodiment is explained based on
The second embodiment differs from the above-mentioned first embodiment in that measures for preventing water condensation are taken in the molten resin not-filled region of the product portion of the mold. The same portions as those in the first embodiment are assigned with the same symbols and their explanation is omitted.
As shown in the cross sectional views of mold essential portions in
The end portion on the product portion 30 side of the communication path 18 is provided with an open/close valve 19 as an open/close means for opening and closing the communication path 18. The open/close valve 19 is provided integrally with the partition plate 16 and as shown in
Although not shown in detail, the open/close valve 19 employs a needle valve and even if the molten resin flows into the product portion 30 when the open/close valve 19 blocks the communication path 18, it is possible to prevent the molten resin from flowing into the communication path 18 without fail.
Further, as shown in
According to the configuration and operation described above, as shown in
A constitution comprising the manifold 12, the arrangement space 15, the communication path 18, and the open/close valve 19 can be said as a heating means in the present embodiment.
As shown in
The arrangement of the cooling pipes 80 is decided while taking into consideration the molding cycle SA for the molded product A in which the entire area in the product portion 30 is filled with the molten resin. Therefore, when the molding cycle SB for molding the molded product B is performed subsequently after the molding cycle SA, if the molten resin not-filled region 32 is not heated, the temperature on the periphery of the molten resin not-filled region 32 shown in
When the temperature at this portion falls below the dew point of the atmosphere in the factory, that is, the atmosphere on the periphery of the mold 1, each time the mold opening process is performed in the molding cycle SB, condensed water is generated on the inner surface of the die forming the molten resin not-filled region 32.
In the state in which the generated condensed water is present, if the molding cycle is switched to the molding cycle SA for molding the molded product A, the molten resin not-filled region 32 in the molding cycle SB in which condensed water is generated is changed into the molten resin filled region 31 in the molding cycle SA and the bracket portion Al of the molded product 1 will be poorly molded by the influence of the condensed water.
However, in the present embodiment, the portion to be the molten resin not-filled region 32 in the molding cycle SB is heated to a temperature higher than the dew point of the atmosphere on the periphery of the mold 1 by utilizing the atmosphere in the arrangement space 15 in which the manifold 12 is arranged, therefore, it is possible to prevent condensed water from being generated and thus prevent poor molding.
Specifically, in the present embodiment, the molding machine is arranged under the conditions that the maximum atmosphere temperature is 32° C. and the maximum atmosphere humidity is 80%. Although the dew point of the atmosphere is 29° C., even when cooling water at a temperature 15° C. is caused to flow through the cooling pipes 80, the portion forming the molten resin not-filled region 32 in the molding cycle SB is kept at about 34° C. by the atmosphere in the arrangement space 15 in which the manifold 12 is arranged. Therefore, even if the molding cycle SB is performed subsequently after the molding cycle SA, it is unlikely that condensed water is generated on the surface forming the product portion 30.
In the present embodiment, as in the first embodiment, in the molding machine that performs the shape changing process of the molten resin filled region 31 of the product portion 30 in accordance with the shape of the molded product to be molded in the next molding cycle during the present one molding cycle, water condensation in the molten resin not-filled region 32 of the product portion 30 is prevented by utilizing the atmosphere in the arrangement space 15 in which the manifold 12 is arranged, however, for the molding machine in the operation of which the molding cycle is stopped in order to move the nest as in the prior art, it is possible to prevent poor molding caused by condensed water by employing the same method for preventing condensation as in the present embodiment for the portion that is no longer in contact with the molten resin when the nest is moved.
The open/close valve 19 in the present embodiment may be a separate part from the partition plate 16 and the valve 19 and the partition plate 16 may be moved by respective drive means.
Next, a third embodiment is explained based on
The third embodiment differs from the first embodiment described above in the configuration for changing the shape of the molten resin filled region of the product portion of the mold. The same portions as those in the first embodiment are assigned with the same symbols and their explanation is omitted.
As shown in the cross sectional views of mold essential portions in
In the operation for reversing the nest 90, first, as shown in
Next, as shown in
After reversing of the nest 90 is completed, as shown in
In this manner, the shape of the molten resin filled region 31 of the product portion 30 shown in
Here, the nest 90 is a shape changing member in the present embodiment and the constitution including the shaft 92A comprising the action means 91 and 93 and the pinion 92, and the shaft 94A comprising the rack 94 is a shape changing member moving means in the present embodiment.
By changing the shape of the molten resin filled region 31 of the product portion 30 by reversing the nest 90 as described above in accordance with the shape of the molded product to be molded in the next molding cycle during one molding cycle, as in the first embodiment, it is not necessary to stop the molding cycle in order to change the shape of the molded product. In this manner, even if the frequency of change in the shape of molded products increases, it is possible to prevent productivity from decreasing.
In the present embodiment also, as shown in
Next, a fourth embodiment is explained based on
The fourth embodiment differs from the first embodiment described above in the configuration for changing the shape of the molten resin filled region of the product portion of the mold. The same portions as those in the first embodiment are assigned with the same symbols and an explanation is omitted.
As shown in the cross sectional views of a mold in
Due to this, the shape of the molten resin filled region 31 of the product portion 30 shown in
Here, the nest 100 is a shape changing member in the present embodiment and the hydraulic cylinder 101 is a shape changing member moving means in the present embodiment.
By changing the shape of the molten resin filled region 31 of the product portion 30 by advancing and retracting the nest 90 as described above in accordance with the shape of the molded product to be molded in the next molding cycle during the present one molding cycle, as in the first embodiment, it is not necessary to stop the molding cycle in order to change the shape of the molded product. In this manner, even if the frequency of changes in shape of molded products increases, it is possible to prevent productivity from decreasing.
In the second and third embodiments described above, water condensation in the molten resin not-filled region is prevented by utilizing the heat of the manifold 12. However, it is not limited to this, and for those that utilize the heat of the heating path forming member for heating the supply path of the resin to the product portion 30, it is possible to prevent water condensation without the need to provide a dedicated heating means. The heating path forming member may be only, for example, a hot sprue.
Further, it may also be possible to prevent water condensation in the molten resin not-filled region by providing a dedicated heating means such as a heater.
In each of the embodiments described above, the shape changing member moving means is a hydraulic cylinder, however, it is not limited to this, and it may be, for example, a servo motor etc.
Further, in each of the embodiments described above, a hot runner system is employed in the resin supply path, however, even when a cold runner system is employed and a molded product is molded in a molding cycle including a process for removing a runner resin, the present invention can be applied effectively. If a process for changing the shape of the molten resin filled region of the product portion is performed in accordance with the shape of a molded product to be molded in the next molding cycle during the present one molding cycle, it is not necessary to stop the molding cycle in order to change the shape of the molded product.
In each of the embodiments described above, two molded products having different shapes are molded using the same mold, however, the present invention can be applied effectively to a case where three or more molded products are molded.
While the invention has been described by reference to specific embodiments chosen for the purposes of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-022497 | Jan 2005 | JP | national |
