ITPD20090056A1 - LOCKING DEVICE FOR COLUMN OF MOLDING PRESSES - Google Patents

Description

LOCKING DEVICE FOR COLUMNS OF PRESSES DI

PRINTING

DESCRIPTION

The present patent relates to locking devices for axially loaded bars or columns, and in particular it concerns a new locking device, particularly for bars or columns of plastic injection molding presses.

Known molding presses comprise a fixed surface and a movable surface adapted to be opposed and pressed against a mold interposed between the platens themselves, where the plastic injection for molding takes place between said fixed platen and said movable platen.

Said movable plane can translate with respect to said fixed plane, approaching or moving away from it, sliding on a sliding plane, and its motion is guided by one or more bars or columns rigidly constrained to said fixed plane and / or by other devices .

During the plastic injection and molding operation, said movable plane must be kept pressed against the mold placed between said fixed plane and said movable plane with a pressure sufficient to counteract the pressure exerted in the mold.

For this purpose, said movable plane is locked and constrained on columns by means of locking devices fitted on each column, each integral with said movable plane and able to lock onto the column preventing any translation of the movable plane.

Locking devices for press columns are known comprising a containment body in which a locking element acting on the column is housed, having a substantially conical or frusto-conical outer surface, comprising an axial notch so as to be substantially flexible in the radial direction, for be able to tighten on said column.

Said conical locking element is inserted in an axially perforated external annular element, having a substantially conical or frusto-conical internal surface, corresponding to said locking element.

Said locking element is axially loaded by means of a spring against a release piston which identifies with said housing body, on the opposite side to said locking element, a chamber into which pressurized fluid can be injected, for example compressed air or oil. The injection / suction of the pressurized fluid in said chamber causes the translation in the axial direction of said piston, whose stroke is limited on one side by said housing body and on the opposite side by a stop element integral with the housing body. housing.

Also said external annular element is axially movable and can be axially loaded by a spring which acts in the opposite direction to said spring acting on said locking element.

In normal conditions, when it is necessary to be able to translate the column with respect to the locking device, the fluid is injected into said chamber, so that said piston pushes the locking element into the release position, counteracting the action of said spring of the locking element.

On the contrary, to block the column, it is sufficient to remove pressure from said chamber, so that said spring pushes the locking element against the external annular element, counteracting the action of the spring of the annular element itself.

Said locking element tightens onto the column due to said external annular element, and axially loads the column itself as well. If the column is further loaded, said spring of the external annular element is unable to counteract its action and the locking element moves further against the piston, which moves to the end of its stroke, while the locking element locking tightens further on said column.

The object of the present patent is a new type of locking system particularly for columns of plastic injection molding presses. The main task of the new locking device is to allow the sliding of the movable plate during the normal operations of opening and closing the mold, and to be able to block the sliding of the movable plate, clamping on the column, also applying a closing force of the plate. movable on the mold interposed between said movable plane and the fixed plane.

Another object of the present invention is to be able to control and precisely adjust the closing force applied to the movable plane, by means of fluid-dynamic devices.

These and other direct and complementary purposes are achieved by the new locking device for columns of plastic injection molding presses, said device being able to be fitted onto a column of the press and constrained to the movable plane.

Said locking device comprises, in its main parts, a containment body, preferably substantially cylindrical, fitted on the column and equipped at the two opposite ends by a front bottom, able to be rigidly constrained to said mobile surface, and by a rear bottom, integral with the containment body itself.

Inside said containment body are housed one or more locking elements or wedges having substantially conical or truncated external surface, suitable for clamping on said column.

Said wedges are tightened against said column by the action of a piston fitted on said column and having an axial frusto-conical or conical bore having a shape corresponding to said external surface of the wedges, that is, able to couple exactly with said wedges.

The surface of the wedges that must come into contact with the surface of said column is expected to be coated with a suitable friction material, while the conical or frusto-conical surface of the piston and / or the wedge is coated with anti-friction material, to minimize dissipative forces due to friction, favoring relative sliding.

Between said front bottom and said piston there is a locking chamber, in which, through a fitting, fluid, such as oil or compressed air, is injected / sucked in order to impart a thrust on said piston in the axial direction and in the direction of moving away from said mobile plane.

Between said rear bottom and said piston there is a release chamber, in which, through a fitting, fluid, such as oil or compressed air, is injected / sucked in order to give a thrust on said piston in the axial direction and in the direction of approaching said moving plane.

Inside said containment body, in front of said rear bottom, there is at least one wedge-holding flange, integral with said wedges and able to translate axially with respect to said containment body and said rear bottom.

The translation of said wedge-carrying flange towards said rear bottom is opposed by at least one elastic means, preferably interposed between said rear bottom and said flange itself, or by the fluid-dynamic action of pressure applied in said release chamber, also acting on said flange itself.

When a positive pressure is applied in said locking chamber, while maintaining a zero or controlled pressure in said unlocking chamber, said piston is pushed to compress said wedges, which tighten on the column.

In this way, the assembly formed by piston, wedge-holding flange, wedges and column substantially constitutes a rigid body.

After the tightening of said wedges on said column, said piston gives said column a traction force in the axial direction, in the direction away from said movable plane.

The group consisting of piston, wedge-holding flange, wedges and column can translate with a stretch stroke, limited by a start or rest position of the wedge-holding flange, i.e. by the position assumed by said flange in the absence of pressure applied in said chamber. or with a certain pressure value in said release chamber, at the end-of-stroke position, identified by the rear bottom.

On the other hand, when the pressure in said locking chamber is canceled and a positive pressure is instead applied in said unlocking chamber, said piston is pushed in the axial direction but in the opposite direction, i.e. in the direction of approaching said movable plane, allowing the wedges to flex radially outwards, returning to rest position and freeing the spine.

Said wedge-holding flange, by effect of said elastic means or by the fluid-dynamic action of said pressure applied in the release chamber, returns to said rest position.

Once released, said column is therefore no longer bound to said locking device, which can translate, integrally with said mobile surface, with respect to said column.

In the preferred solution, it is envisaged that said locking chamber and said release chamber do not communicate with the column, so that the column never comes into contact with the operating fluid, in order to guarantee the seal of the gaskets even in the event of accidental damage. of the column itself.

The characteristics of the new invention will be better clarified by the following description with reference to the drawing tables, attached by way of non-limiting example.

Figure 1 schematizes in section the new device according to a first embodiment solution.

In figure 2 the new device is schematized in section according to a further possible embodiment solution, while figure 2a illustrates a detail.

The new locking device can be applied on each of the columns (A) of presses equipped with at least one fixed surface and at least one movable surface (E), translating with respect to said fixed surface and to said columns (A).

The new locking device comprises a containment body (D) fitted on said column (A) and equipped at the two opposite ends by a front bottom (D1), able to be rigidly constrained to said mobile surface (E), and by a rear pad (D2).

Inside said containment body (D) there are one or more locking elements or wedges (B) acting on the surface of said column (A), said wedges (B) having an external surface (B1) substantially conical or truncated cone and adapted to be clamped on the column (A) itself by the action of at least one piston (C) having an internal surface (C1) substantially conical or truncated cone of a shape corresponding to said external surface (B1) of the wedges (B), for mate exactly with said wedges (B) themselves.

In a possible solution, the new device is expected to comprise two or more of said wedges (B), preferably three or four, distributed radially around the column (A) and all constrained to a wedge-holding flange (G, Gâ € ™) , for example by means of screws (G2).

In particular, it can be envisaged that the shank of the screw is inserted in a spring (G3) preloaded by compression, having the function of facilitating and guiding the widening of the wedges (B) with respect to the column (A) during the release phase.

Inside said containment body (D), between said front bottom (D1) and said piston (C), there is at least one locking chamber (F), in which, through a fitting (F1), there is injected / aspirated of the operating fluid in order to impart a thrust on said piston (C) in the axial direction (X) and in the direction away from said movable plane (E). Inside said containment body (D), between said rear end cap (D2) and said piston (C) there is at least one release chamber (L), into which, through a fitting (L1), it is injected / aspiration of the operating fluid, in order to impart a thrust on said piston (C) in the axial direction (X) but in the opposite direction of approach to said mobile plane (E).

When a positive pressure is applied in said locking chamber (F), maintaining a zero or controlled pressure in said unlocking chamber (L), said piston (C) is pushed to compress said wedges (B), which tighten on the column (TO).

After the tightening of said wedges (B) on said column (A), maintaining a zero or controlled pressure in said release chamber (L), said piston (C) impresses on said column (A), through said wedges (B) themselves, a traction force in the axial direction (X), in the direction of moving away from said movable plane (E).

On the contrary, when a positive pressure is applied in said release chamber (L), while maintaining zero pressure in said locking chamber (F), said piston (C) is pushed in the axial direction (X) but in the opposite direction, that is, in the direction of approach to said mobile plane (E), allowing the wedges to flex radially outwards, freeing the column (A).

According to a first embodiment, shown in section in figure 1, inside said containment body (D), in front of said rear bottom (D2), there is at least one wedge holder flange (G), integral with said wedges (B), adapted to translate axially, and where its translation towards said rear bottom (D2) is opposed by at least one elastic means (H) interposed between said flange (G) and said rear bottom (D2).

In particular, said release chamber (L) is identified between said wedge holder flange (G) and said piston (C), while between said wedge holder flange (G) and said rear bottom (D2) a chamber is identified, hereinafter referred to as the stretching chamber (N).

In the locking phase, as mentioned, by applying a positive pressure in said locking chamber (F), while maintaining zero pressure in said unlocking chamber (L), said piston (C) acts on said wedges (B) which tighten on the column (A).

Once tightened, said piston (C), said wedge-holding flange (G), said wedges (B) and said column (A) form a group which substantially constitutes a single body, and where said group translates with a stretching stroke ( m) maximum limited by a position of start of stroke or rest of the wedge-holding flange (G), i.e. from the position assumed by said flange in the absence of pressure applied in said locking chamber (F), to the end-of-stroke position, where said flange wedges holder (G) is abutment on said rear pad (D2).

On the contrary, when a positive pressure is applied in said release chamber (L), maintaining zero pressure in said locking chamber (F), said wedge-holding flange (G) returns to said rest position due to the effect of said means elastic (H).

According to the alternative solution schematized in figure 2, inside said containment body (D) there is at least one wedge-holding flange (Gâ € ™), integral with the rear part of said wedges (B) and comprising at least one surface stop (G1â € ™), on which the pressure applied in said release chamber (L) acts, and at least one further rear flange (I), connected to said wedge holder flange (Gâ € ™), and where said rear end cap (D2) is substantially interposed with a clearance (m) between said flange (Gâ € ™) and said rear flange (I).

In the blocking phase of the column (A), by increasing the pressure in said blocking chamber (F) and maintaining a determined value of pressure in said release chamber (L), said wedge-holding flange (Gâ € ™) is kept in stroke start or rest position, while said piston (C) acts on said wedges (B) which tighten on said column (A).

Said position of start of travel or rest is determined by the stop between the rear flange (I) and the rear end plate (D2).

In the stretching phase of the column (A), after the tightening of said wedges (B) on said column (A), the group formed by said piston (C), said wedges (B), said wedge-holding flange (Gâ € ™ ) and said column (A), translates by a maximum limited stroke (m) between said stroke start or rest position and a stroke end position, delimited by the contact between said abutment surface (G1â € ™) and said rear bottom (D2).

In the column unlocking phase (A), when a positive pressure is applied in said unlocking chamber (L), while maintaining zero pressure in said locking chamber (F), said wedge-holding flange (Gâ € ™) returns to said rest position due to the pressure applied in said release chamber (L) on said abutment surface (G1â € ™) of said wedge-holding flange (Gâ € ™) itself.

According to this second solution, the operation of the new device is extremely simplified and is completely fluid-dynamic, i.e. it does not make use of elastic means in any way, and also has a smaller number of components overall than known locking devices, thus involving fewer construction and assembly costs. In the preferred solution, the surface (B2) of said wedges (B) in contact with the surface of said column (A) is also covered with friction material, while the conical or frusto-conical surface (C1, B1) of said piston (C) and / or said wedges (B) is coated in anti-friction material, to minimize dissipative forces due to friction, favoring relative sliding.

It is also envisaged that said locking chamber (F) and said release chamber (L) do not communicate with said column (A), so that the column (A) never comes into contact with the operating fluid.

These are the schematic modalities sufficient for the skilled person to realize the invention, consequently, in concrete application there may be variations without prejudice to the substance of the innovative concept.

Therefore, with reference to the above description and the attached tables, the following claims are expressed.

Claims (1)

CLAIMS 1. Locking device for columns (A) of presses with at least one fixed surface and at least one movable surface (E), comprising a containment body (D) fitted on said column (A) and equipped, at the two opposite ends, with a front bottom (D1), able to be rigidly constrained to said mobile surface (E), and a rear bottom (D2), inside said containment body (D) being housed one or more locking elements or wedges (B) acting on the surface of said column (A), having an external surface (B1) substantially conical or frusto-conical and able to be tightened on the column (A) itself by the action of at least one piston (C) having an internal surface (C1) substantially conical or truncated cone of shape corresponding to said external surface (B1) of the wedges (B), to couple exactly with said wedges (B) themselves, characterized in that: â € ¢ between said front end cap (D1) and said piston (C) there is a locking chamber (F), in which, through a fitting (F1), the operating fluid is injected / aspirated in order to give a thrust on said piston (C) in the axial direction (X) and in the direction away from said movable plane (E); â € ¢ between said rear end cap (D2) and said piston (C) there is a release chamber (L), in which, through a fitting (L1), the operating fluid is injected / aspirated, in order to impart a thrust on said piston (C) in the axial direction (X) and in the direction of approaching said movable plane (E); and where, when a positive pressure is applied in said locking chamber (F), maintaining a zero or controlled pressure in said unlocking chamber (L), said piston (C) is pushed to compress said wedges (B), which tighten on the column (A), while when a positive pressure is applied in said release chamber (L), maintaining a zero or controlled pressure in said locking chamber (F), said piston (C) is pushed in the axial direction ( X) but in the opposite direction, that is, in the direction of approach to said mobile plane (E), allowing the wedges to flex radially outwards, freeing the column (A). 2. Locking device, as per claim 1, characterized in that, after having tightened said wedges (B) on said column (A), continuing to apply a positive pressure in said locking chamber (F) and maintaining a zero or controlled pressure in said release chamber (L), said piston (C) imparts to said column (A), through said wedges (B), a traction force in the axial direction (X), in the direction of removal from said moving floor (E). 3. Locking device, as per claims 1, 2, characterized in that at least one wedge-holding flange (G ), integral with said wedges (B), able to translate axially, and where its translation towards said rear bottom (D2) is opposed by at least one elastic means (H), said release chamber (L) being identified between said wedge holder flange (G) and said piston (C). 4. Locking device, as per claim 3, characterized in that a stretching chamber (N) is identified between said wedge-holding flange (G) and said rear bottom (D2), and where, by applying a positive pressure in said locking chamber (F), maintaining zero pressure in said release chamber (L), after having tightened said wedges (B9 on said column (A), the group formed by said piston (C), said flange wedges holder (G), said wedges (B) and said column (A) translates with a maximum stretching stroke (m) limited by a start position or rest position of the wedge holder flange (G), i.e. by the position assumed by said flange in the absence of pressure applied in said locking chamber (F), at the end-of-stroke position, identified by the stop of said wedge-holding flange (G) on said rear bottom (D2). 5. Locking device, as per claims 1, 2, characterized in that at least one wedge-holding flange (Gâ € ™) is located inside said containment body (D), integral with the rear part of said wedges (B) comprising at least one abutment surface (G1â € ™) on which the pressure applied in said release chamber (L) acts, and at least one further rear flange (I) integral with said wedge-holding flange (Gâ € ™ ), said rear bottom (D2) being at least partly substantially interposed with clearance between said wedge-holding flange (Gâ € ™) and said rear flange (I) and where: â € ¢ by applying a positive pressure in said locking chamber (F) and maintaining a determined pressure value in said unlocking chamber (L), said wedge holder flange (Gâ € ™) is kept in the start position or rest, where said rear flange (I) abuts on said rear bottom (D2), and said wedges (B) tighten on said column (A); â € ¢ after having tightened said wedges (B) on said column (A), maintaining a positive pressure in said locking chamber (F), the group formed by said piston (C), said wedges (B) , said wedge-holding flange (Gâ € ™) and said column (A) translates with a maximum stroke (m) from said start or rest position to an end position, where said abutment surface (G1â € ™) is ̈ abutment on said rear cap (D2). 6. Locking device, as per claims 1, 2, 3, 4 or 5 characterized in that when a positive pressure is applied in said unlocking chamber (L), while maintaining zero pressure in said locking chamber (F) , said wedge-holding flange (G, Gâ € ™) returns to said rest position by effect of said elastic means (H) or said pressure applied in said release chamber (L) on said abutment surface (G1â € ™) of said wedge-holding flange (Gâ € ™) itself. 7. Locking device, as per the preceding claims, characterized in that the surface (B2) of said wedges (B) in contact with the surface of said column (A) is coated with friction material. 8. Locking device, as per the preceding claims, characterized in that the conical or frusto-conical surface (C1, B1) of said piston (C) and / or said wedges (B) is coated in anti-friction material, to minimize dissipative forces due to friction, favoring relative sliding. 9. Locking device, as per the preceding claims, characterized in that said locking chamber (F) and said release chamber (L) do not communicate with said column (A), so that column (A) never enters in contact with the operating fluid.