RU240309U1 - Device for locking the molds of a PET blow molding power plant - Google Patents

Abstract

This utility model pertains to plastic blow molding, specifically to devices for clamping molds in a power unit for blow molding PET containers from preheated preforms. The piston sizes of the pneumatic compression cylinders are reduced, simplifying the manufacturing process for the mold locking device and reducing the force exerted by each piston on the movable mold holder, thereby improving safety. The mold locking device comprises two movable mold halves holders located within a frame containing horizontal plates and two vertical plates. Pneumatic compression elements are located between the movable holders and the vertical plates. Each element comprises a movable base with two pistons attached to it. The pistons are housed in cylinders of a cylinder body attached to a vertical plate. The vertical plate is equipped with nozzles for supplying gas to the cylinders. The movable base is pressed against the vertical plate by dampers. In the piston attachment area, the movable base is equipped with a lever attachment point. The corresponding lever mounting point is also located on the corresponding mold half-mold holder. The mounting points are connected to the clamping pneumatic cylinders via a system of levers.

Description

Field of technology.

The technical solution relates to the field of plastic blow molding, namely to devices for clamping press molds in a power unit for blowing PET containers from an already heated preform.

Prior art.

A known PET blow molding machine (patent RU2458793, IPC B29C 49/28, B29C 49/56, 2012) comprises a frame with horizontal beams and vertical fixed plates. Movable mold holders are positioned between the vertical plates. Pneumatic pressure cylinders are mounted on the vertical plates. The cylinders exert force on the mold holders via transverse locking of the stops.

A disadvantage of this alternative is that the pneumatic clamping system is implemented using a single power cylinder. The mold locking device must provide sufficient clamping force across the entire height of the part being manufactured. To achieve this, the power cylinder of this alternative is significantly larger—its surface area must be larger than the area of the parts being blown (bottles). Furthermore, the pressure in the cylinder must exceed the pressure in the mold when the bottle is being blown. Manufacturing such a power cylinder is technologically complex, as it requires high manufacturing precision and the use of machines capable of processing large parts.

Furthermore, the force exerted by each power cylinder on the moving mold holder is significant. This force is calculated as the product of the air pressure in the cylinder and the piston's effective area. Since the power cylinder in the prototype covers the entire area of the PET container being blown, its piston area is significant. Consequently, the force exerted by each power cylinder on the moving mold holder is significant. If a power cylinder fails, this force is misdirected—not on the moving mold holder, but on non-target components, which reduces the safety of the device or requires more material-intensive protective measures.

Disclosure of the claimed technical solution.

The technical problem that the claimed technical solution is aimed at solving is to simplify the manufacturing technology of a mold locking device and to increase the safety of this device.

The technical result achieved by the claimed technical solution is a reduction in the size of the pneumatic compression cylinder pistons, which eliminates the need to ensure high precision in the manufacture of large parts of the mold locking device during its production.

Another technical result is a reduction in the force exerted by each pneumatic press element piston on the movable mold holder. In the event of failure of the corresponding pneumatic press element piston, this results in less destructive impact on non-target components of the device, which increases the device's safety or reduces the material consumption of protective measures against pneumatic press element failure.

The essence of the claimed technical solution is that the mold locking device of a PET blow molding power unit comprises two movable mold half holders located within the interior of a frame comprising horizontal plates and two vertical plates. A pneumatic compression element is secured to the interior of the frame on each vertical plate. Each pneumatic compression element comprises a movable base with two pistons attached to it, each piston located within a cylinder housing secured to the vertical plate. Each vertical plate is equipped with gas supply nozzles for each of the aforementioned cylinders. Each movable base is secured to the vertical plate of the frame via dampers located on the reverse side of the vertical plate, allowing it to be pressed against the vertical plate. Furthermore, in the area where each piston attaches to the movable base on the side facing the mold half holder, the movable base is equipped with a lever mount. The corresponding lever mounting location is also located on the corresponding mold half-holder. The mold locking device for each mold half-holder is equipped with a pneumatic clamping cylinder, which is connected via a system of levers to the lever mounting locations on the corresponding mold half-holder and the sliding base.

The above-mentioned entity is a set of essential features of the declared technical solution that ensure the achievement of the declared technical results.

It's easier to achieve higher precision on small parts. Small cylinders allow for machining on more lathes, easier to control dimensions and tolerances, two small cylinders are cheaper in terms of both production costs and manufacturing time than one large one, and easier to transport between workshop areas.

In special cases, it is permissible to implement a technical solution in the following manner.

Each cylinder body preferably has a groove on the surface adjacent to the vertical plate around each cylinder, in which a seal is placed, and each piston of the pneumatic compression elements is equipped with seals on the side surface.

Each piston of the pneumatic compression elements is preferably provided with a step on the end adjacent to the movable base, and the cylinder body is provided with corresponding protective flanges, which are designed with the ability to engage with the steps of the said pistons when the latter are extended from the cylinders to such a significant extent that this does not correspond to the normal operation of the pneumatic compression element.

The attachment points of the levers on the movable base can be located in the areas of projections of the geometric center of the pneumatic compression pistons onto the corresponding surface of the movable base, and the corresponding attachment points on the half-mold holder are made to lie with the corresponding attachment points of the levers on the movable base, essentially on one straight line, parallel to the direction of movement of the movable bases during operation of the device.

The author of the declared technical solution has produced a sample of this solution, the testing of which confirmed the achievement of the technical result.

Brief description of the drawings.

Fig. 1 shows the external view of the PET container blowing power unit, Fig. 2 shows the external view of the power unit from the side, Fig. 3 shows the external view of the pneumatic pressing element, Fig. 4 shows a large longitudinal section of the pneumatic pressing element.

List of reference designations:

1 - horizontal metal frame plates;

2 - frame;

3 - carriage-manipulator;

4 - half-mold holder;

6 - pneumatic clamping cylinder;

7 - pneumatic clamping element;

8 - damper;

9 - lever system;

10 - pneumatic cylinder for lifting the bottom plate of the press mold;

11 - blowing block;

12 - half-form;

13 - heating unit mounting beam;

14 - vertical frame plates;

15 - movable plate of the pneumatic clamping element;

16 - piston of the pneumatic compression element;

17 - cylinder body of the pneumatic booster element;

18 - nipple;

19 - damper bolt;

20 - place of attachment of levers to the movable plate of the pneumatic clamping element;

21 - place of attachment of levers to the half-mold holder;

22 - seal;

23 - piston seals;

24 - piston stage;

25 - protective rim of the cylinder body.

Implementation of a technical solution.

The device for locking the press molds of the PET bottle blow molding power unit comprises a rectangular frame (Fig. 1, 2) mounted on a metal bed (2), including horizontal (1) and vertical plates (14). In the internal space of the frame, formed by the horizontal and vertical plates, two movable holders (4) of the halves of the press molds (half molds) (12) are located. The holders (4) are vertical metal plates facing each other, fixed on an L-shaped bed. The holders are mounted on horizontal guides (rails) with the possibility of counter movement. The horizontal guides are fixed on the lower horizontal plate (1) of the frame.

On the inside of the frame, a pneumatic clamping element (7) is attached to each vertical plate (14).

Each pneumatic clamping element comprises a movable base (15) with two pistons (16) secured to it and a cylinder body (17) (Fig. 1, 2, 3). The base may structurally be a plate, beam, crossbar or any other element suitable for this purpose. In Fig. 3, the movable base is shown as made in the form of a rectangular cross-section bar. The cylinder body (17) is secured to the vertical plate (14) and has a groove on the surface adjacent to it around each cylinder, into which a seal (22) is placed, preventing the loss of gas (air) during the operation of the pneumatic clamping unit through the gap between the cylinder body and the vertical plate (Fig. 4). Each piston (16) is placed in the cylinder body (17) between the movable base (15) and the vertical plate (14) of the frame. On the side surface, the piston is provided with seals (23), preventing the loss of gas (air) during the operation of the pneumatic compressor through the gap between the piston and the cylinder body. Between the piston (16) and the vertical plate (14) in the cylinder body (17) a sealed space is formed. The vertical plate of the frame is provided with separate nozzles (18) for supplying gas (air) under pressure to each of the above-mentioned sealed spaces. To limit the maximum stroke, the piston (16) is provided with a step (24) on the end adjacent to the movable base (15), while the cylinder body is provided with corresponding protective rims (25). The height of the steps is selected such that when the piston is extended from the cylinder so significantly that this does not correspond to the normal operation of the pneumatic compressor element, the piston step rests against the protective rim of the cylinder body, preventing further extension of the piston.

Each movable base (15) is connected to the vertical frame plate via two dampers (8) located on the reverse side of the vertical frame plate. The head of the bolt (19) rests against the damper (8), pressing it against the outer surface of the vertical frame plate, and the thread of the bolt (19) is screwed into a threaded hole in the movable base (15). The bolts (19) pass freely through the corresponding holes in the vertical frame plate. Thus, the bolts (19) attract the movable base (15) to the vertical frame plate (14) with a force generated by the compression of the dampers (8).

On the side facing the half-mold holder (4), two attachment points (20) for the levers (9) are located on the movable base (15). One attachment point corresponds to one piston. Each attachment point (20) is located in the region of its corresponding piston. The attachment point is preferably located in the region of the projection of the piston's geometric center onto the corresponding surface of the movable base. If the piston (16) is cylindrical, the corresponding attachment point (20) is preferably located on the piston axis.

The mold half-mold holders also contain attachment points (21) for the levers (9). One attachment point (21) for the levers on the mold half-mold holder corresponds to one attachment point (20) for the levers on the movable bases. The attachment point (21) on the mold half-mold holder is aligned with the corresponding attachment point (20) for the levers on the movable base, essentially on the same line, parallel to the direction of movement of the movable bases during operation of the device.

The housings of the pneumatic clamping cylinders (6) are secured to the lower horizontal plate (1) of the frame. The length-adjustable rods of these pneumatic cylinders are secured to a lever system (9) capable of converting the reciprocating motion of the clamping pneumatic cylinder rod into the reciprocating motion of the half-mold holders. A separate pneumatic clamping cylinder with its own lever system is provided for each half-mold holder. The lever system (9) acts on the movable plates of the pneumatic clamping element and the half-mold holders (4) at the attachment points (20, 21).

In the central part, the body of the pneumatic cylinder (10) for lifting the plate of the bottom part of the press mold is fixed to the lower horizontal plate (1) of the frame.

The following are also fixed to the frame:

- blowing block (11) with nozzle;

- beam (13) for fastening the heating unit;

- carriage-manipulator (3). Description of work.

Before using the PET blow mold locking device, PET blow mold halves (12), designed to produce one part at a time, are secured to the facing surfaces of the holders (4). The bottom portion of the half mold is secured to the bottom plate.

In the initial position, the holders (4) of the half-molds are spaced apart relative to each other, and the bottom plate is lowered.

After the preheated PET preforms are transferred from the oven to the mold area by the manipulator carriage (3), the clamping pneumatic cylinders (6), acting with their rods on the lever systems (9), move the mold holders (4) toward each other until the mold halves touch. Simultaneously, the bottom plate is lifted by the corresponding pneumatic cylinder (10). The mold halves and the bottom section are closed.

At the same time, the blowing block (11) is lowered.

Following this, high-pressure compressed air (gas) is supplied to the space between the cylinders (16) and the vertical plates (14) of the frame through the nozzles (18). The movable bases (15), overcoming the elastic forces of the dampers (8), move away from the vertical plates (14). The resulting forces are transmitted from the attachment points (20) to the attachment points (21) by the lever systems (9), resulting in the compression of the mold halves with great force.

After the mold is closed by the pneumatic press (7), the blowing unit (11) delivers air (gas) under high pressure, under pre-blow pressure, through the nozzle into the preform neck, inflating it. The blowing unit then delivers high-pressure air (gas), finally forming the PET container. The compression force of the holders (4) by the pneumatic press (7) is slightly greater than the force exerted on the mold halves by the product, due to the larger total area of the pistons compared to the surface area of the product acting on the mold, which reliably prevents the mold from opening and creating defects.

Once the molding process is complete, the air (gas) pressure is released from the mold cavity, and then, or simultaneously, from the pneumatic pressurization cavities. This causes the movable bases (15), under the action of dampers (8), to be pressed against the vertical plates (14) of the frame, and the pneumatic pressurization pressure on the mold holders is relieved.

The carriage-manipulator grasps the finished product by the neck.

Then the holders (4) are moved apart using the pneumatic clamping cylinders (6) and the lever systems (9). At the same time, the bottom part is lowered downwards due to the action of the pneumatic cylinder (10).

After this, the finished product is removed from the half-molds and the carriage-manipulator (3) moves it to the delivery area.

Industrial applicability.

The proposed technical solution is implemented using industrially available devices and materials, can be manufactured at any industrial facility, and will find wide application in the field of blow molding PET containers from heated preforms.

Claims (4)

1. A device for locking press moulds of a PET bottle blow moulding power unit, comprising two movable mould halves holders located in the interior of a frame containing horizontal plates and two vertical plates, wherein a pneumatic compression element is secured to the interior of the frame on each vertical plate, characterized in that each pneumatic compression element comprises a movable base with two pistons secured to it, located in the cylinders of a cylinder body secured to a vertical plate, which is provided with nozzles for supplying gas to each of the said cylinders, wherein each movable base is secured to the vertical plate of the frame through dampers located on the reverse side of this vertical plate, with the possibility of being pressed against this vertical plate, wherein in the area of attachment of each piston to the movable base on the side facing the half mould holder, this movable base is provided with a place for attaching levers, and the place for attaching levers corresponding to this place is also located on the corresponding half mould holder, wherein the mold locking device for each half-mold holder is equipped with a pneumatic clamping cylinder, which is connected through a system of levers to the attachment points of the levers on the corresponding half-mold holder and the movable base. 2. The device according to paragraph 1, characterized in that each cylinder body has a groove on the surface adjacent to the vertical plate around each cylinder, in which a seal is placed, and each piston of the pneumatic compression elements is provided with seals on the side surface. 3. The device according to paragraph 1, characterized in that each piston of the pneumatic compression elements is provided with a step on the end adjacent to the movable base, and the cylinder body is provided with corresponding protective flanges, which are designed with the ability to engage with the steps of the said pistons when the latter are extended from the cylinders to such a significant extent that this does not correspond to the normal operation of the pneumatic compression element. 4. The device according to paragraph 1, characterized in that the attachment points of the levers on the movable base are located in the areas of the projections of the geometric center of the pneumatic compression pistons onto the corresponding surface of the movable base, and the corresponding attachment points on the half-mold holder are made to lie with the corresponding attachment points of the levers on the movable base, in essence, on one straight line, parallel to the direction of movement of the movable bases during operation of the device.