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) through which a compression rod (5) passes in a sealed manner 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,so that a displacement of the annular piston (4) towards the lower end of the body (3) compresses the upper chamber (8) and displaces the liquid from the upper chamber (8) to the lower chamber (7), which simultaneously causes the lower chamber (7) to expand and the compression rod (5) to move from a position retracted into the body (3) to a position extended from the body (3), in which the upper end of the rod is intended to compress the powder. Figure for the abbreviation: 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 a press equipped with such a punch. Previous 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 back and forth, 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 generally 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, that is to say with two sets of punches facing each other to compress the powder.

[0008] Also known from the prior 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, opposite 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 a hydraulic one, allows the lower punch to be actuated. It comprises a cylinder 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 by as a consequence by acting on solenoid valves.

[0013] The control unit also allows the desired dosing 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 hydraulics of the punch.

[0015] Document FR2141434 is also known, which describes an operation quite similar 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 cross member, a lower cross member, and an intermediate cross member. A die-holding table and a lower punch-holding table slide freely between the intermediate and upper cross members. The intermediate cross member carries a double-acting, double-rod cylinder that is actuated by fluid pressure.

[0018] When the fluid is introduced into the cylinder, the main rod extends and reaches an adjustable stop fixed to the lower punch-holder table. Simultaneously, a counter-rod extends and raises the die-holder table connected to it. This creates an adjustable dosing chamber, the height of which is determined by the position of the stop. The powder is then introduced into the chamber.

[0019] Next, by reintroducing the pressurized fluid into the cylinder, the main rod and the upper punch move downwards, compressing the powder between the punches. An adjustable stop can limit the upward stroke of the die-holding table.

[0020] Once compression is complete, fluid is admitted above the cylinder piston, raising the lower punch-holder table and the lower punch. Compression from below continues until a predetermined pressure is reached. Then, fluid is admitted above the piston to raise the cylinder and the moving assembly to their initial position to eject the compressed material.

[0021] This document also relates to double punch presses, and their implementation remains complex. Driving the lower punch also requires the use of an external power source. Description 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 dosing height of a press, in particular a single-punch rotary press.

[0023] To this end, a punch comprising a tubular body with a The body consists of a closed lower end and an open upper end. Internally, it comprises a sealed annular piston through which a compression rod passes, sealed to close the open upper end of the body. The compression rod has a non-sealed piston at its lower end, creating, within the body and on either side of the rod's piston, a lower chamber and an upper chamber of varying volumes, each filled with a liquid. Movement of the annular piston towards the lower end of the body compresses the upper chamber and displaces the liquid from the upper chamber to the lower chamber, simultaneously causing the lower chamber to expand and the compression rod to move from a position retracted within the body to a position extended from the body, where 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 displacement 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 sticks from compressed powder.

[0026] Preferably, the upper end of the compression rod includes a head piston intended to engage tightly in a compression column of a die of a press, which ensures efficient compression of the powder in the compression column of the die, thus ensuring the quality and uniformity of the solid tablets or sticks 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 pressure setting and 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, which is closed by a plug.

[0031] In this way, it allows for 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 achieved in several ways; a spring is disposed in the upper chamber, bearing against the piston. annular part of the body and against the piston of the rod, to move them away from each other.

[0033] The fluidic communication of the upper and lower chambers of the body can be achieved in any suitable way, for example with a gap between the piston and the body, or the non-sealed piston includes orifices intended for this communication.

[0034] The invention also relates to a press for manufacturing solid tablets or sticks from a powder, comprising means for axially moving the punch, a die having a powder compression column.

[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-support against the annular piston of the punch to move it towards the lower end of the body in order to cause the movement of the liquid from the upper chamber to the lower chamber and, concomitantly, 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 in the column of the die.

[0036] This makes it possible to increase the dosing height of a standard single-punch press in order, 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 push 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. 1 is a longitudinal sectional view of three hydraulic punches at different stages of compression, driven by a cam of a single-punch rotary press. Detailed description of the invention

[0040] With reference to [Fig. 1], the present invention relates to a hydraulic punch (1) for use in a press (2), particularly a single-punch rotary press, for manufacturing solid tablets or sticks from a powder. The punch (1) is characterized by its innovative structure and operation, which enable efficient powder compression and 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 the powder to be compressed. The invention finds an advantageous application for compressing a powder with a dosing height of 100 mm, in order to create solid sticks that can fit into a neck. 20mm.

[0041] The punch (1) consists of a tubular body (3) with a closed lower end and an open upper end. Inside the body (3) is a sealed annular piston (4), through which a compression rod (5) passes in a sealed manner, closing the open upper end of the body (3). The annular piston (4) has an external O-ring that provides a seal between the body (3) and the annular piston (4), and an internal O-ring that provides a seal 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-sealed piston (6) at its lower end, with a diameter larger than that of the rod (5), thus creating a lower chamber (7) and an upper chamber (8) of varying 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 ports (6a) for connecting the upper (8) and lower (7) chambers, allowing a fluid 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 extended from the body (3). During the extension, the upper end of the compression rod (5) compresses the powder.

[0046] This configuration maximizes the stroke of the hydraulic punch (1) since it corresponds to the sum of the stroke provided by the cam and the stroke of the compression rod (5). This is how the powder dosing height can be increased because the compression stroke of the punch (1) is lengthened. 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 produce both powder tablets and powder sticks taller than a tablet on the same press (2), using the hydraulic punch (1) according to the invention.

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

[0048] The upper end of the compression rod (5) is provided with a head piston (9), with an external O-ring, which engages tightly 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), ensures 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 together, allowing for easy assembly and disassembly of the punch (1). Furthermore, the lower end of the body (3) has a bore (12) opening into the lower chamber (7), which is closed, for example, by a screw-on plug, thus enabling convenient filling and emptying of liquids into the upper and lower chambers of the punch (1).

[0050] To ensure the proper functioning of the punch (1), a spring (13) is disposed 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) allows these elements to be separated from each other and maintains an appropriate pressing force, and allows the compression rod (5) to retract once the compression is complete in order to begin 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 powder compression column (10) and is positioned axially against the annular piston (4) of the punch (1). In practice, the die (11) comprises, for example, a cylindrical bearing surface (1a) in which the compression rod (5) engages, thus providing circular support 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 be moved 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) can be in the form of a cam (14) adapted to move the punch (1) by axial push against the lower end of the body (3) of the punch (1).

[0054] The described invention has many advantages and technical effects. It allows for efficient compression of the powder in the manufacture of solid tablets or sticks, with an increased range of motion 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, thereby 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-support 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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