Hydraulic punch for rotary press, and rotary press equipped with such a punch

Abstract

The invention relates to a punch (1) of a press (2), such as a single-punch rotary press for manufacturing solid tablets or sticks from a powder. According to the invention, the punch comprises a tubular body (3) with a closed lower end and an open upper end, the body (3) internally comprising a sealed annular piston (4) traversed in a sealed manner by a compression rod (5) for closing the open upper end of the body (3), the compression rod (5) having a non-sealed piston (6) at a lower end so as to delimit in the body (3) and on either side of the piston (6) of the rod (5), a lower chamber (7) and an upper chamber (8), of variable volumes and filled with a liquid,such that a movement of the annular piston (4) towards the lower end of the body (3) compresses the upper chamber (8) and moves the liquid from the upper chamber (8) towards the lower chamber (7) which concomitantly causes the expansion of the lower chamber (7) and the movement of the compression rod (5) from a position retracted into the body (3) towards a position extracted from the body (3) in which the upper end of the rod is intended to compress the powder. Figure for the abstract: Fig. 1,

Description

Title of the invention: Hydraulic punch for rotary press, and rotary press equipped with such a punch Technical field

[0001] The present invention relates to the technical field of presses, such as rotary presses used for example to manufacture tablets from powdered material for the cosmetic or pharmaceutical industry.

[0002] The present invention relates to a hydraulic punch for such presses, as well as to a press equipped with such a punch. Prior art

[0003] In current manufacturing processes, the use of single-punch rotary presses is common for compressing powder and forming solid tablets.

[0004] These presses comprise only one set of punches, generally positioned in the lower part, and moved in back and forth movements, to compress the powder in a die, against the support of an anvil for example.

[0005] However, these presses have limitations in terms of dosing height, which limits production capacity. Standard single-punch rotary presses typically have a dosing height of approximately 45 mm.

[0006] The dosing height of these single-punch rotary presses is not easily adaptable, and in this case, it proves difficult to double the dosing height in order to manufacture solid sticks.

[0007] In practice, in order to increase the dosing height, double punch presses are most often used, i.e. with two sets of punches facing each other to compress the powder.

[0008] Also known from the state of the art is document JP2004034130 which describes a powder molding machine used for the manufacture of tablets or pills.

[0009] This document provides for the use of upper and lower punches, facing each other, to compress the powder.

[0010] In particular, the lower punch closes a die to allow the powder to be deposited, and the upper punch then moves vertically to press the powder.

[0011] A drive mechanism, in particular hydraulic, is used to actuate the lower punch. It comprises a jack fixed to a plate, a piston and a cylinder.

[0012] A control unit uses position information from a linear sensor to calculate the target position of the punch and adjust the vertical movement accordingly. consequence by acting on solenoid valves.

[0013] The control unit also allows the desired dosage height to be adjusted.

[0014] This system is more particularly suited to double punch presses, but its disadvantage lies in its complexity, and in particular in the use of an external energy source to control the solenoid valves and the punch hydraulics.

[0015] Also known is document FR2141434 which describes an operation quite close to that presented above.

[0016] This document describes a compression press which allows powder to be compressed between an upper punch and a lower punch to form solid products.

[0017] The press comprises a frame with an upper crossbar, a lower crossbar and an intermediate crossbar. A die table and a lower punch table slide freely between the intermediate crossbar and the upper crossbar. The intermediate crossbar carries a double-acting, double-rod cylinder which is actuated by fluid pressure.

[0018] When the fluid is introduced into the cylinder, the main rod extends and reaches an adjustable stop attached to the lower punch table. At the same time, a counter rod extends and lifts the die table connected to it. This creates an adjustable metering chamber whose height is determined by the position of the stop. The powder is then introduced into the chamber.

[0019] Then, by re-introducing the pressurized fluid into the cylinder, the main rod and the upper punch move downward, compressing the powder between the punches. An adjustable stop can limit the upward travel of the die table.

[0020] Once compression is complete, fluid is admitted above the ram piston, causing the lower punch table and lower punch to rise. Compression from below continues until a predetermined pressure is reached. Then, fluid is admitted above the piston to cause the ram and moving assembly to rise to their initial position to eject the tablet.

[0021] This document also relates to double punch presses, and remains complex in its implementation. The control of the lower punch also requires the use of an external energy source. Statement of the invention

[0022] One of the aims of the invention is therefore to remedy the problems of the prior art by providing a hydraulic punch which makes it possible to increase the metering height of a press, in particular a single-punch rotary press.

[0023] For this purpose, a punch has been developed comprising a tubular body with a closed lower end and an open upper end. The body internally comprises a sealed annular piston through which a compression rod passes in a sealed manner to close the open upper end of the body. The compression rod has a non-sealed piston at a lower end so as to delimit in the body and on either side of the piston of the rod, a lower chamber and an upper chamber, of variable volumes and filled with a liquid, so that a movement of the annular piston towards the lower end of the body compresses the upper chamber and displaces the liquid from the upper chamber towards the lower chamber which concomitantly causes the expansion of the lower chamber and the movement of the compression rod from a position retracted into the body to a position extracted from the body in which the upper end of the rod is intended to compress the powder.

[0024] The punch according to the invention finds an advantageous application in a single-punch press for the manufacture of solid tablets or sticks from a powder.

[0025] The hydraulic punch according to the invention makes it possible to obtain the movement of an internal compression rod, thus increasing the dosing height of a standard single-punch rotary press, which makes it possible to increase the production rate of solid rods from compressed powder.

[0026] Preferably, the upper end of the compression rod comprises a head piston for sealingly engaging a compression column of a die of a press, thereby ensuring efficient compression of the powder in the compression column of the die, thereby ensuring the quality and uniformity of the solid tablets or rods produced.

[0027] According to a particular embodiment, the head piston is screwed axially to the upper end of the compression rod, which facilitates the assembly and disassembly of the punch, thus allowing easy maintenance of the equipment.

[0028] Furthermore, it is possible to consider using head punches of different thicknesses to adjust the setting of the pressure and the dosing height.

[0029] Preferably, the body is in two coaxial parts screwed into each other, in order to offer greater flexibility for assembly and disassembly, thus facilitating the handling and replacement of certain parts of the punch.

[0030] According to a particular embodiment, the lower end of the body has a bore opening into the lower chamber, closed by a plug.

[0031] In this way, it allows convenient filling and emptying of liquids in the upper and lower chambers of the punch.

[0032] The return of the piston to the retracted compression rod position can be done in several ways. A spring is arranged in the upper chamber pressing against the piston. annular of the body and against the piston of the rod, to move them away from each other.

[0033] The fluid communication of the upper and lower chambers of the body can be done in any suitable manner, for example with a clearance between the piston and the body, or the non-sealed piston comprises orifices intended for this communication.

[0034] The invention also relates to a press for the manufacture of solid tablets or sticks from a powder, comprising means for axial movement of the punch, a die having a column for compressing a powder.

[0035] According to the invention, the press comprises at least one punch according to one of the aforementioned characteristics, with the die positioned in axial counter-pressure against the annular piston of the punch to move it towards the lower end of the body in order to cause the liquid to move from the upper chamber to the lower chamber and, concomitantly, the compression rod to move from a position retracted into the body to a position extracted from the body in which the upper end of the rod is intended to compress the powder in the column of the die.

[0036] This makes it possible to increase the dosing height of a standard single-punch press, for example, to manufacture solid sticks at an industrial rate.

[0037] Preferably, the press is a rotary press, and the means for axially moving the punch are in the form of a cam adapted to move the punch by axial thrust against the lower end of the punch body.

[0038] These technical characteristics and advantages make the invention innovative and advantageous compared to the prior art in the field of manufacturing solid tablets or sticks from compressed powder. Brief description of the drawings

[0039] [Fig.l] is a view, in longitudinal section, of three hydraulic punches at different stages of compression, pushed by a cam of a single-punch rotary press. Detailed description of the invention

[0040] With reference to [Fig.l], the present invention relates to a hydraulic punch (1) for use in a press (2), in particular a single-punch rotary press, for the manufacture of solid tablets or rods from a powder. The punch (1) is characterized by its innovative structure and operation, which make it possible to obtain efficient compression of the powder and to improve the performance of the press (2). The design of the punch (1) according to the invention makes it possible in particular to increase the dosing height of powder to be compressed. The invention finds an advantageous application for compressing a powder with a dosing height of 100mm, in order to create solid rods which can fit into a neck 20mm.

[0041] The punch (1) is composed of a tubular body (3) with a closed lower end and an open upper end. Inside the body (3) there is a sealed annular piston (4), through which a compression rod (5) passes in a sealed manner, which closes the open upper end of the body (3). The annular piston (4) has an external O-ring which ensures sealing between the body (3) and the annular piston (4), and an internal O-ring which ensures sealing between the annular piston (4) and the compression rod (5).

[0042] In other words, it is the assembly of the sealed annular piston (4) and the compression rod (5) which makes it possible to close the upper opening of the body (3).

[0043] The compression rod (5) has a non-sealing piston (6) at its lower end, of a diameter larger than that of the rod (5), thus creating a lower chamber (7) and an upper chamber (8) of variable volumes on each side of the piston (6) of the rod (5).

[0044] The non-sealed piston (6) of the punch (1) is for example equipped with orifices (6a) for connecting the upper (8) and lower (7) chambers, allowing a smooth transfer of the liquid during the expansion of the lower chamber (7) and the movement of the compression rod (5).

[0045] When the annular piston (4) is moved towards the lower end of the body (3), the upper chamber (8) is compressed, causing the liquid to move from the upper chamber (8) to the lower chamber (7). This compression of the upper chamber (8) and the concomitant expansion of the lower chamber (7) cause the compression rod (5) to move from a position retracted into the body (3) to a position extracted from the body (3). During extraction, the upper end of the compression rod (5) compresses the powder.

[0046] This configuration makes it possible to maximize the stroke of the hydraulic punch (1) since this corresponds to the sum of the stroke given by the cam and the stroke of the compression rod (5). This is how the dosing height of the powder can be increased because the compression stroke of the punch (1) is extended. In practice, this technique makes it possible, for example, to double the dosing height stroke of a standard single-option rotary press (2), and therefore to be able to produce both powder tablets and powder sticks of a height greater than that of a tablet, on the same press (2), with the hydraulic punch (1) according to the invention.

[0047] Furthermore, the fluid movements inside the punch (1) are managed automatically and mechanically, without requiring an external energy supply, such as a control unit or a hydraulic circuit with solenoid valves. The hydraulic punch (1) according to the invention is autonomous.

[0048] The upper end of the compression rod (5) is provided with a head piston (9), with an external O-ring, which engages in a sealing manner in a compression column (10) of a die (11) of the press (2). This head piston (9), screwed axially to the upper end of the compression rod (5), guarantees efficient and uniform compression of the powder in the column of the die (11).

[0049] The body (3) of the punch (1) may consist of two coaxial parts (3a, 3b) screwed into each other, which allows easy assembly and disassembly of the punch (1). In addition, the lower end of the body (3) has a bore (12) opening into the lower chamber (7), closed for example by a screw cap, thus allowing convenient filling and emptying of liquids in the upper and lower chambers of the punch (1).

[0050] To ensure the proper functioning of the punch (1), a spring (13) is arranged in the upper chamber (8) bearing against the annular piston (4) of the body (3) and against the piston of the rod. This spring (13) makes it possible to move these elements away from each other and to maintain an appropriate bearing force and to allow the retraction of the compression rod (5) once the compression is complete in order to be able to carry out another compression cycle.

[0051] The invention also relates to the press (2) for manufacturing solid tablets or sticks from a powder. This press (2) is equipped with at least one hydraulic punch (1) as described above. The die (11) of the press (2) has a compression column (10) for the powder and is positioned in axial counter-pressure against the annular piston (4) of the punch (1). In practice, the die (11) comprises, for example, a cylindrical bearing surface (11a) in which the compression rod (5) engages, thus providing circular pressure on the annular piston (4).

[0052] This allows the annular piston (4) to be moved towards the lower end of the body (3), when the punch (1) is moved axially upwards, causing the liquid to move from the upper chamber (8) to the lower chamber (7) and the concomitant movement of the compression rod (5) to achieve the compression of the powder in the column (10) of the die (11).

[0053] If the press (2) is a rotary press, the means for axially moving the punch (1) may be in the form of a cam (14) adapted to move the punch (1) by axial thrust against the lower end of the body (3) of the punch (1).

[0054] The described invention has numerous technical advantages and effects. It allows efficient compression of the powder in the manufacture of solid tablets or sticks, with an increased range of movement of the compression rod which makes it possible to increase the dosing height of the powder.

[0055] It also offers ease of assembly, disassembly and maintenance of the punch thanks to its modular structure. In addition, the use of the rotary press and the cam ensures continuous and efficient operation of the press, thus improving manufacturing productivity.

Claims

Claims

1. Punch (1) of a press (2), such as a single-punch rotary press for the manufacture of solid tablets or sticks from a powder, characterized in that it comprises a tubular body (3) with a closed lower end and an open upper end, the body (3) internally comprising a sealed annular piston (4) traversed in a sealed manner by a compression rod (5) to close the open upper end of the body (3), the compression rod (5) having a non-sealed piston (6) at a lower end so as to delimit in the body (3) and on either side of the piston (6) of the rod (5), a lower chamber (7) and an upper chamber (8), of variable volumes and filled with a liquid,such that a movement of the annular piston (4) towards the lower end of the body (3) compresses the upper chamber (8) and moves the liquid from the upper chamber (8) towards the lower chamber (7) which concomitantly causes the expansion of the lower chamber (7) and the movement of the compression rod (5) from a position retracted into the body (3) towards a position extracted from the body (3) in which the upper end of the rod is intended to compress the powder.,

2. Punch (1) according to claim 1, characterized in that the upper end of the compression rod (5) comprises a head piston (9) intended to engage in a sealed manner in a compression column (10) of a die (11) of a press (2).

3. Punch (1) according to claim 2, characterized in that the head piston (9) is screwed axially to the upper end of the compression rod (5).

4. Punch (1) according to one of the preceding claims, characterized in that the body (3) is in two coaxial parts (3a, 3b) screwed into each other.

5. Punch (1) according to one of the preceding claims, characterized in that the lower end of the body (3) has a bore (12) opening into the lower chamber (7), closed by a plug.

6. Punch (1) according to one of the preceding claims, characterized in that a spring (13) is arranged in the upper chamber (8) bearing against the annular piston (4) of the body (3) and against the piston (6) of the rod (5), to move them away from each other.

7. Punch (1) according to one of the preceding claims, characterized in

8.

9. that the non-sealed piston (6) comprises orifices (6a) for connecting the upper and lower chambers. Press (2) for the manufacture of solid tablets or sticks from a powder, comprising means for axial displacement of the punch (1), a die (11) having a compression column (10) of a powder, characterized in that it comprises at least one punch (1) according to one of the preceding claims, and in that the die (11) is positioned in axial counter-pressure against the annular piston (4) of the punch (1) to move it towards the lower end of the body (3) in order to cause the displacement of the liquid from the upper chamber (8) towards the lower chamber (7) and, concomitantly, the displacement of the compression rod (5) from a position retracted into the body (3) towards a position extracted from the body (3) in which the upper end of the rod is intended to compress the powder in the column of the die (H). Press (2) according to claim 8, characterized in that it is rotary, and the means for axial displacement of the punch (1) are in the form of a cam (14) adapted to move the punch (1) by axial thrust against the lower end of the body (3) of the punch (1).

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