DESCRIPTION

The present patent application generally relates to an apparatus for molding a plastic bucket, and more particularly to a mold with an integrated automatic system for the assembling of handles, which is optimized for the production of customized plastic buckets. Over the years, the production techniques of plastic buckets have evolved due to requirements related with the visibility and the advertising of contents on the bucket. The above has resulted in a series of innovations in the search for product customization, such as labeling, screen printing, hot transfer, and co-printing of In-Mold Labeling (IML) films.

The use of the IML customization technique has originated some problems that need to be solved, while guaranteeing a high productivity and a high graphic quality of the final product. In order to obtain these characteristics, a specific automation must be used to position the films inside the mold. Such an automation must be included in the process and integrated with the assembly of the handle on the bucket. Hence the need to integrate the entire production system of the bucket as much as possible.

The production techniques of plastic buckets according to the prior art can be divided into three categories:

1) Separate production

The buckets and the handles are produced with separate molds, in two different production lines comprising two different molding machines, one for the bucket and one for the handle respectively, and an automation system, such as a robot, which assembles the handle in the bucket. Obviously, such a technology is expensive and cumbersome due to the presence of the two production lines and of the automation means.

2) Co-molding The bucket and the handle are co-molded in a single cavity of a mold. Such a methodology is not very much used because the mold is very complicated, prone to wear and not very productive. In addition, such a methodology only allows for producing buckets with handles that are not in contact with the bucket. This type of buckets is bulky and is not suitable in some particular fields of use. Moreover, these buckets are produced in one integral piece, with preset breaking points of the handle, in such a way that, after being detached from the bucket, the handle can be used normally.

3) Simultaneous production

Molding apparatuses are known, which allow for producing the bucket and the handle in the same apparatus provided with a mold for the bucket and a mold for the handle. After molding the bucket and the handle, the mold for the handle is moved in such a way to assemble the handle on the bucket. Such a molding apparatus is complex because of the movement of the mold for the handle.

W09822273A1 discloses an apparatus comprising a lower mold half and an upper mold half that can be coupled together in such a way to define a first cavity for a bucket and a second cavity for a handle provided with pins that are fastened in seats of the bucket. The apparatus comprises application means to fasten the pins of the handle to the seats of the bucket. Each application means comprises an arm with one end that is suitable for pushing the pin of the handle in order to fasten it to the seat of the bucket and an actuator to move the arm. Said application means are extremely complicated and expensive to make.

EP2281673A1 discloses an injection mold assembly of a bucket with a handle. The assembly comprises a first mold half comprising a circular cavity and a second mold half comprising a base and a central core suitable for penetrating into the circular cavity in such a way to form a chamber defining the shape of the bucket. Two slides are provided above the base of the second mold half. One of the slides comprises two cylindrical members to form two holes in opposite position on the bucket and a semi-circular impression to form the handle with two pins. Actuators are used to push the pins of the handle in the seats of the bucket. After molding the bucket and the handle, the two slides must be moved apart in such a way that the cylindrical members are removed from the holes of the bucket and the pins of the handle are aligned with the holes of the bucket. Successively, the actuators must be activated to introduce the pins of the handle in the holes of the bucket. Such a solution is rather complicated because it is necessary to move both the two mold halves and the two slides.

The purpose of the present invention is to eliminate the drawbacks of the prior art by providing a molding apparatus capable of simultaneously molding a bucket and a handle and assembling the handle on the bucket.

Another purpose of the present invention is to provide such a molding apparatus that is efficient, effective, and suitable for minimizing the production time and costs of a bucket with a handle.

Another purpose of the present invention is to provide such a molding apparatus that is inexpensive and simple to make.

Another purpose of the present invention is to provide such a molding apparatus that is compact and versatile.

These purposes are achieved in accordance with the invention with the features of the appended independent claims. Advantageous embodiments of the invention appear from the dependent claims.

The apparatus according to the invention is defined in the dependent claim 1 . The apparatus according to the invention allows for producing a plastic bucket with a handle. The automation for assembling the handle on the bucket is comprised in the apparatus.

Such an apparatus reduces costs significantly because of the elimination of an external automation for assembling the handle, and increases the speed of the production process, with consequent lower costs.

Advantageously, the apparatus according to the invention provides for assembling two different handles, according to the specific requirements, without having to modify said apparatus.

Additional features of the invention will appear clearer from the detailed description below, which refers to a purely illustrative and therefore non-limiting embodiment thereof, illustrated in the appended drawings, wherein:

Fig. 1 is a top view of the apparatus according to the invention;

Fig. 2 is a perspective view of the apparatus of Fig. 1 in an initial position;

Fig. 3 is a perspective view of the apparatus according to the invention in an intermediate step of the process, after molding, wherein the handle (not shown) has been picked by the picking means;

Fig. 4 is an enlarged view of a detail of Fig. 3, which shows the picking means of the handle in a raised position;

Fig. 5 is a perspective view of the apparatus according to the invention, in a final step of the process, wherein the picking means assemble the handle on the bucket (not shown);

Fig. 6 is an enlarged view of a detail of Fig. 5, which shows the picking means during the assembly of the handle on the bucket;

Fig. 7 is a perspective view of a bucket molded with the apparatus according to the invention, which shows two types of handles in an exploded view; Fig. 8 is a sectional view that shows a portion of bucket and a portion of the handle assembled on the bucket.

With reference to the Figures, an apparatus for molding a plastic bucket according to the invention is described, which is collectively indicated with reference numeral 100.

Referring now to Figs. 1 and 2, the apparatus (100) comprises a base plate (4) suitable for being coupled with a semi-mold (not shown) opposite to the base plate (4) in such a way to define a mold that comprises a first cavity (1) suitable for molding a bucket (200) (shown in Fig. 7) and a second cavity (2) suitable for molding a handle (300) (shown in Fig. 7) that is suitable for being assembled on the bucket (200).

Optionally, the apparatus (100) may comprise a third cavity (3) for molding a handle (300’) (shown in Fig. 7) which is different from the handle molded in the second cavity (2). For example, the second cavity (2) is configured to produce a handle (300) of ribbon-like type and the third cavity (3) is configured to produce a shaped handle (300') with ribs and grooves.

The base plate (4) and the semi-mold of the mold are mounted in a press which reciprocally moves the base plate (4) and the semi-mold in such a way to open and close the mold.

The first cavity (1) is suitably shaped to obtain two fastening seats (201 ) in the bucket (200) in diametrically opposite positions near an upper edge of the bucket for fastening the handle.

The first cavity (1 ) is obtained by means of a male punch (10) with cylindrical or truncated-conical shape that protrudes in upper position from the base plate (4), in a central position of the base plate. The semi mold will have a female housing that is coupled with the male punch (10) of the base plate to obtain the first cavity (1 ) wherein plastic material is injected for molding the bucket (200). The second cavity (2) is suitably shaped to obtain two fastening pins (301 ) in the handle (300) near the ends of the handle. With reference to Fig. 8, the fastening pins (301) of the handle are suitable for being engaged in the fastening seats (201 ) of the bucket in fit-in coupling mode.

The second cavity (2) is obtained by means of an insert (20) mounted on the base plate (4), in a peripheral position relative to the male punch (10). The insert (20) has a seat (21) shaped like an arc of circumference with concavity directed towards the male punch (10). The insert (20) has a central portion (22) and two lateral portions (23). The semi-mold will have a counter-insert that is coupled with the insert (20) of the base plate to obtain the second cavity (2) wherein plastic material is injected for molding the handle (300) of ribbon-like type.

The third cavity (3) is suitably shaped to obtain two fastening pins (301 ) in the handle (300) near the ends of the handle. Said fastening pins (301 ) of the handle are suitable for being engaged in the fastening seats (201 ) of the bucket in fit-in coupling mode.

The third cavity (3) is obtained by means of an insert (30) mounted on the base plate (4) in a peripheral position relative to the male punch (10) and in a diametrically opposite position relative to the insert (20) of the second cavity. The insert (30) of the third cavity has a seat (31 ) shaped like an arc of circumference with concavity directed towards the male punch (10). The seat (31 ) of the insert of the third cavity is provided with ribs and grooves. The insert (30) of the third cavity has a central portion (32) and two lateral portions (33). The semi-mold will have a counter-insert that is coupled with the insert (30) of the base plate in order to obtain the third cavity (3) wherein plastic material is injected to mold a shaped handle (300’).

The mold comprises:

- the base plate (4), and

- the semi-mold, not shown in the Figures. The base plate (4) has the male punch (10), the insert (20) and the insert (30).

The semi-mold comprises:

- a seat that is coupled with the punch (10) to generate the first cavity (1) for the bucket (200),

- a first counter-insert that is coupled with the insert (20) to generate the second cavity (2) for the handle (200), and

- a second counter-insert that is coupled with the insert (30) to generate the third cavity (2) for the handle (300).

The apparatus (100) comprises picking means (M) suitable for picking the handle (300; 300') molded in the second cavity (2) or in the third cavity (3), positioning said handle (300; 300') in correspondence with the bucket (200) disposed above the male punch (10), and assembling the handle on the bucket, in such a way that the fastening pins (301) of the handle are engaged in the fastening seats (201) of the bucket.

The picking means (M) comprise a pair of trolleys (5) that are slidingly mounted on the base plate (4), in a peripheral position relative to the male punch (10).

Each trolley (5) has a shaft (50) that protrudes from the trolley in order to be fitted into the lateral portion (23) of the insert in such a way that one end of the shaft (50) is located in the second cavity (2) to engage the fastening pin (301 ) of the handle that has been molded in the second cavity (2). For such a purpose, the fastening pin (301 ) of the handle has a hole (302) (Fig. 8) that is open outwardly in order to accommodate an end of the shaft (50).

Each trolley (5) is moved between an initial position near a lateral portion (23) of the insert (that is to say near the fastening pin (301 ) of the handle disposed in the second cavity (2)) to a final position near the fastening seat (201) of the bucket disposed in the first cavity (1). Each trolley (5) is moved linearly on a respective guide (6). The guides (6) are parallel to each other and disposed in opposite positions relative to the male punch (10).

Each trolley (5) is moved by a linear actuator (7) (Fig. 6). The linear actuator (7) may be a cylinder-piston assembly of pneumatic, hydraulic or electromagnetic type, or it may be a screw-female screw assembly or a gear-rack assembly driven by an electric motor.

Each trolley (5) comprises a lower portion (51) and an upper portion (52) that is slidably mounted on the lower portion (51 ) to go from a lowered position to a raised position relative to the lower portion (51 ).

Fig. 2 illustrates the upper portion (52) of the trolley in lowered position. Fig. 4 illustrates the upper portion (52) of the trolley in raised position.

Upper portion actuation means (A1) move the upper portion (52) relative to the lower portion (51 ) of the trolley. The upper portion actuation means (A1) comprise springs disposed between the lower portion (51 ) and the upper portion (52) to move the upper portion (52) away from the lower portion (51). Alternatively, the upper portion actuation means (A1 ) may comprise an actuator that raises/lowers the upper portion (52).

The trolley (5) comprises adjustment means (R) (Fig. 4) to adjust the translation travel of the upper portion (52) relative to the lower portion (51) of the trolley.

The shaft (50) of the trolley is connected to a flange (53) that protrudes from the trolley, in opposite position to the shaft (50). The shaft (50) is slidably mounted in the upper portion (52) of the trolley to go from a retracted position to an extracted position.

Fig. 4 shows the shaft (50) in retracted position. Fig. 6 shows the shaft (50) in extracted position.

Shaft actuation means (A2) move the shaft (50) between the retracted position and the extracted position. The shaft actuation means (A2) comprise:

- spring means (54) disposed between the flange (53) and the upper portion (52) of the trolley in such a way to push the flange (53), stressing the shaft (50) toward its retracted position; and

- a linear actuator (8) suitable for pushing the flange (53) to move the shaft (50) toward its extracted position.

The linear actuator (8) of the shaft actuation means (A2) may be a cylinder-piston assembly of pneumatic, hydraulic or electromagnetic type, or it may be a screw-female screw assembly or a gear-rack assembly driven by an electric motor.

Two linear actuators (8) are mounted on the base plate (4) in diametrically opposite positions relative to the male punch (10), in correspondence with the fastening seats (201) of the bucket molded into the first cavity (1 ). In such a way, when the trolley (5) is in its final position, in correspondence with the fastening seats (201) of the bucket molded in the first cavity (1), the linear actuators (8) can push the flange (53) and move the shaft (50) toward its extracted position.

Advantageously, the picking means (M) comprise a first pair of trolleys (5) to pick the handle (300) molded in the second cavity (2) and a second pair of trolleys (5) to pick the handle (300') molded in the third cavity (3).

In such a case there are always two guides (6) and two linear actuators (8) of the shaft actuation means that are used both for the trolleys (5) of the first pair and for the trolleys of the second pair.

Following is a description of the operation of the apparatus

(100).

Initially, the mold is open; the trolleys (5) are disposed in the initial positions near the lateral portions (23) of the insert (20); the upper portion (52) of the trolleys is in raised position; the shafts (50) of the trolleys are in retracted position. The mold is closed, consequently the upper portion (52) of the trolleys is lowered in lowered position, and the end of the shafts (50) enters the second cavity (2) in the point where the fastening pins (301 ) of the handle will be molded. Plastic material is injected into the first cavity (1) and the second cavity (2). In view of the above, the bucket (200) is molded in the first cavity and the handle (300) is molded in the second cavity. The fastening pins (301 ) of the handle are engaged by the ends of the shafts (50). The mold is opened, consequently the upper portion (52) of the trolleys is raised to a raised position by means of the upper portion actuation means (A2), which consist in springs. As a result, the handle

(300) is raised by the shafts (50) of the trolleys and is extracted from the seat (21 ) of the insert. The linear actuators (7) of the trolleys are actuated; then the trolleys (5) are moved from the initial position to the final position, bringing the handle (300) close to the bucket (200) which is disposed on the male punch (10). In view of the above, the fastening pins (301) of the handle are disposed in correspondence with the fastening seats (201) of the bucket.

The actuators (8) of the shaft actuation means are actuated in order to push the flanges (53) so that the shafts (50) are moved from the retracted position to the extracted position, pushing the fastening pins

(301 ) of the handle inside the fastening seats (201 ) of the bucket. The spring means (54) bring the shafts (50) back to the retracted position, and the actuators (7) of the trolleys bring the trolleys (5) to the initial position in order to begin a new molding cycle.

Although the description of the operation of the apparatus (100) refers to the handle (300) molded in the second cavity (2), the apparatus operates similarly for the handle (300') molded in the third cavity (3).

Compared to the apparatus described in W09822273A1 , the apparatus (100) according to the invention is extremely simpler and cheaper to realize thanks to the fact that the picking means consist in trolleys (5) that are mounted slidingly on the base plate (4), wherein each trolley has the shaft (50) that protrudes from the trolley so that the end of the shaft (50) can enter the second cavity (2) to engage the fastening pin (301 ) and apply it to the seats of the bucket. Furthermore, the apparatus (100) according to the invention is much simpler than EP2281673A1 because the insert or the two inserts (20, 30) defining the cavities (2, 3) for the handles (300, 300') are fixed and not movable.

Numerous equivalent changes and modifications may be made in the present embodiment of the invention, which are within the scope of a person skilled in the art, without departing from the scope of this invention as expressed by the appended claims.