US20180133784A1 - Mold for injection-compression molding - Google Patents
Mold for injection-compression molding Download PDFInfo
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- US20180133784A1 US20180133784A1 US15/816,527 US201715816527A US2018133784A1 US 20180133784 A1 US20180133784 A1 US 20180133784A1 US 201715816527 A US201715816527 A US 201715816527A US 2018133784 A1 US2018133784 A1 US 2018133784A1
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- United States
- Prior art keywords
- mold
- punch
- matrix
- piece
- pressure
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C15/00—Moulding machines characterised by the compacting mechanism; Accessories therefor
- B22C15/02—Compacting by pressing devices only
- B22C15/08—Compacting by pressing devices only involving pneumatic or hydraulic mechanisms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/002—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure using movable moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/20—Accessories: Details
- B22D17/22—Dies; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/56—Means for plasticising or homogenising the moulding material or forcing it into the mould using mould parts movable during or after injection, e.g. injection-compression moulding
- B29C45/561—Injection-compression moulding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/56—Means for plasticising or homogenising the moulding material or forcing it into the mould using mould parts movable during or after injection, e.g. injection-compression moulding
- B29C45/561—Injection-compression moulding
- B29C2045/5635—Mould integrated compression drive means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/56—Means for plasticising or homogenising the moulding material or forcing it into the mould using mould parts movable during or after injection, e.g. injection-compression moulding
- B29C45/561—Injection-compression moulding
- B29C2045/5665—Compression by transversely movable mould parts
Definitions
- the present invention relates to a mold for injection-compression molding and a relative molding method.
- Injection-compression molding differs from the traditional molding process in the injection step, which takes place when the mold is open.
- the injection-compression process involves an initial step in which the mold has an initial opening before the injection step: this increases the volume of the cavity, which is partially filled by the molten material.
- the molten material is then compressed by the closing movement of the mold and the mold filling time is completed as a result.
- An alternative method involves filling the entire mold, and the compression step compensates only for the volumetric shrinkage of the molten material that solidifies. This is followed by the steps of cooling and extraction of the piece.
- the final distribution in the mold, compaction and compensation of the shrinkage of the material occur by compression, by closing the mold through the movement of the press.
- FIGS. 1-6 show schematic views of steps of a molding sequence according to the present invention
- FIG. 7 shows a schematic top view of a perimetral ring according to the present invention.
- FIG. 8 shows a schematic view of the hydraulic circuit, integrated in the mold, for moving the perimetral ring
- FIG. 9 shows an enlargement of a detail of FIG. 5 , in which a perimetral ring is shown, in an embodiment example according to the present invention, in the closing step (between matrix and punch) of the mold;
- FIGS. 10-11 show further embodiment examples of the perimetral ring.
- reference numeral 1 globally denotes a mold for injection compression molding (ICM).
- Mold 1 comprises a punch 2 and a matrix 3 suitable to close on the punch 2 so as to delimit with this an injection chamber 10 to contain the material to be injected.
- Matrix 3 and punch 2 are axially movable between them with respect to an axial direction Y-Y of opening/closing of mold 1 .
- mold 1 further comprises a perimetral ring 4 , slidingly associated to punch 2 or matrix 3 , along the axial direction Y-Y, in which the perimetral ring 4 defines, together with matrix 3 and punch 2 , the profile of the injection chamber 10 .
- Mold 1 is characterised in that the closure between matrix 3 and punch 2 is accomplished using a perimetral ring 4 having a special shape of an interface wall with matrix 3 above, or with punch 2 .
- the perimetral ring 4 comprises a matrix interface profile 43 intended to engage with matrix 3 , and a punch interface profile 42 , intended to engage with punch 2 .
- the matrix interface profile 43 is equipped with a particular geometry suitable to generate a compression force of ring 4 towards the inside of mold 1 .
- the matrix interface profile 43 is convex, preferably convex polygonal.
- the matrix interface profile 43 comprises an inclined upper thrust wall 443 , on which an inclined plane 34 associated with matrix 3 is engaged.
- matrix 3 pushes on the perimetral ring 4 , and in particular on the upper thrust wall 443 , thus generating a force F, substantially transversal to the axial direction Y-Y and directed towards the inside of mold 1 , which allows correctly retaining the perimetral ring 4 , thus ensuring a correct support.
- the perimetral ring 4 comprises, between the matrix interface profile 43 and the punch interface profile 42 , an inner profile 41 which at least partially defines the profile of the injection chamber 10 .
- the perimetral ring 4 defines, with the inner profile 41 , the profile of the injection chamber 10 in all the molding process steps, i.e. in the mold closing step ( FIG. 2 ), in the molten material injection step ( FIG. 3 ), in the compression step ( FIG. 4 ) up to the compression end step ( FIG. 5 ).
- the perimetral ring 4 defines a portion of the profile of the injection chamber 10 between matrix 3 and punch 2 . Therefore, the perimetral ring 4 defines at least partially the profile of the piece, together with matrix 3 and punch 2 .
- the inner profile 41 of the perimetral ring 4 defines at least partially the profile of the piece.
- the perimetral ring 4 is interposed between matrix 3 and punch 2 : such a solution allows obtaining double junction points on the piece.
- a double junction point is created in the mold by the coupling of two metal surfaces.
- a first double junction point (J 1 ) is formed on the piece between punch 2 and perimetral ring 4 , and a second double junction point (J 2 ) between perimetral ring 4 and matrix 3 .
- J 1 a first double junction point
- J 2 a second double junction point
- the fact that at least a portion of the perimetral ring 4 defines the profile of the piece allows producing pieces with rounded edges, as shown in FIG. 10 . This solution is very important for pieces intended to come into contact with the user's skin.
- the fact that at least a portion of the perimetral ring 4 defines the profile of the piece allows to perform an aesthetic photoengraving or embossing treatment (T pattern in bas-relief made in negative on matrix 3 ), as shown in FIG. 11 .
- This solution in which the piece has a wavy surface, is very important for pieces intended for the automotive industry, and in general for pieces intended to have an aesthetic value.
- the perimetral ring 4 defines at least partially thickness S of piece P, together with punch 2 . Such a solution allows effectively hiding the junction points on the piece.
- the inner profile 41 of the perimetral ring 4 defines, together with punch 2 , a first double junction point (J 1 ) at thickness S of the piece.
- the inner profile 41 of the perimetral ring 4 defines, together with matrix 3 , a second double junction point (J 2 ) at an outer edge C of the piece.
- the first double junction point (J 1 ) is placed at thickness S of the piece, and the second double junction point (J 2 ) is placed at an outer edge C of the piece.
- the second double junction point (J 2 ) derives from a flattening closure: it is therefore easy to make with good quality, and without being visible in the finished piece (being placed at an outer edge C of the piece).
- the first double junction point (J 1 ) is instead by its geometric and technological nature difficult if not impossible to hide.
- the double junction point (J 1 ) is also concealed and not visible to the user as it is placed at thickness S of the piece.
- there are no visible junction lines on the piece which is very important for pieces intended to be aesthetic details.
- Mold 1 is also characterised in that the closing of the injection chamber 10 takes place on the perimetral ring 4 , a ring that defines together with punch 2 thickness S of the piece, so that the juncion line is placed on the thickness (i.e. within thickness S) of the piece to be molded.
- Mold 1 is operated by axial movement means (not shown) of matrix 3 and/or punch 2 to accomplish the opening and closing of the mold, hereinafter referred to as mold movement means.
- Extraction mean 9 (not shown) act on mold 1 adapted to extract the piece from the mold.
- Mold 1 is characterised in that the perimetral ring 4 is actuated by means of hydraulic cylinders 51 actuated by a hydraulic circuit 7 capable of controlling the pressure in all process steps.
- a hydraulic circuit 7 which further comprises a valve assembly 71 , 73 , 72 , is integrated into mold 1 .
- Mold 1 comprises movement means 5 of the perimetral ring 4 adapted to carry out the advancement and retraction of the ring within the mold, hereafter referred to as ring movement means.
- the ring movement means 5 comprise a hydraulic circuit 7 (shown in FIG. 8 ) provided with actuating cylinders 51 activated/deactivated by hydraulic controls commonly found in injection presses (and referred to as radial). Usually, and disadvantageously, radials can only be used in standard presses when the mold is open.
- the hydraulic circuit 7 comprises a first hydraulic control 91 (referred to as radial one) and a second hydraulic control 92 (referred to as radial two).
- the radial or hydraulic control works with the following logic: if the hydraulic control is ON, the pressurised oil provides a constant pressure equal to the set pressure; if the control is OFF, the oil in the hydraulic circuit is free to flow towards a tank at atmospheric pressure. This last step is called ‘exhaust pressure’.
- the hydraulic circuit 7 for moving ring 5 is thus connected and managed directly by the hydraulic control 91 (or radial one) of the press.
- the hydraulic circuit 7 comprises a first non-return valve 71 , of the type with release controlled by pressure, directly controlled by radial two 92 .
- the hydraulic circuit 7 further comprises a pressure relief valve 73 , which allows setting the pressures of the circuit and which can be calibrated between zero and the pressure of radial one.
- the hydraulic circuit 7 further comprises a second non-return valve 72 .
- the hydraulic circuit further comprises a pressure gauge 76 , to which a valve 75 is associated, for pressure control.
- the hydraulic circuit 7 comprises a series of T-unions 74 .
- the ring movement means 5 comprise a plate 50 which can be lifted by means of the actuating cylinders 51 of the ancillary hydraulic circuit.
- Plate 50 is provided with axial pins 52 connected to the perimetral ring 4 .
- Plate 50 also referred to as “table”, is intended to ensure the coordination and parallelism of the movement (lifting and retraction) of pins 52 and thus, of the perimetral ring 4 .
- Plate 50 is provided with a constant preload, provided by the actuating cylinders 51 of the hydraulic circuit 51 by means of the pressure relief valve 73 .
- the hydraulic circuit 7 is integrated in mold 1 and is connected to the first hydraulic control 91 (referred to as radial one) and to the second hydraulic control 92 (referred to as radial two).
- This solution allows ensuring both the necessary seal of the closure and the absence of residual forces when opening mold 1 , thus avoiding the ejection of the piece at the same time as the opening.
- FIGS. 1 to 7 show the operating diagram of mold 1 and of the perimetral ring 4 , moved by the ring movement means 5 and by the hydraulic circuit 7 .
- FIG. 5 shows the compression step with completely closed mold, i.e. with matrix 3 closed on punch 2 .
- the perimetral ring 4 even if completely retracted due to the thrust of matrix 3 , pushes on piece P: the actuating cylinders 51 of hydraulic circuit 7 are active and at constant pressure given by the pressure relief valve 73 .
- Radial two is pressurised: acting on the non-return valve 71 it causes the release of pressure of the hydraulic circuit 7 : the actuating cylinders 51 drop to zero pressure and the perimetral ring 4 stops pushing on the piece.
- FIG. 6 shows the opening step of the open mold, i. e. matrix 3 raised with respect to punch 2 , and the perimetral ring 4 in the retracted and at rest position (i.e. not in thrust).
- the actuating cylinders 51 having lost pressure, do not push the piece during the opening step of mold 1 so that it does not fall out before the picking robot arrives.
- the extraction of the piece is carried out by means of special extractors (not shown), while the pressure in the hydraulic circuit 7 for the movement of the perimetral ring 4 remains at zero until the extraction has taken place.
- FIG. 1 shows the mold still open but the perimetral ring 4 is now in the advanced position (or in thrust) for a new molding cycle.
- Radial one connected directly to the ring movement circuit 5 , is put under pressure and the perimetral ring 4 moves forward. At this point, the pressure in radial one is reset to zero (and it could not be otherwise in a standard press), while in the hydraulic circuit 7 , due to the non-return valves 71 , 72 , pressure remains to the value set in pressure relief valve 73 (which can be calibrated between zero and the pressure of radial one).
- mold 1 closes and the perimetral ring 4 , pushed forward by the actuating cylinders, 51 , retracts under the thrust of matrix 3 .
- the retraction of the perimetral ring 4 reduces the volume of oil in the actuating cylinders 51 , and in the hydraulic circuit 7 the constant pressure given by the pressure relief valve 73 remains.
- FIG. 3 shows the injection step of the molten material into the injection chamber 10 .
- FIG. 4 shows the compression step of the material. Mold 1 resumes closing, squeezing the molten material inside the injection chamber 10 . As shown in FIG. 8 , the molten material is pushed towards the edges of the injection chamber 10 when mold 1 is still open, but its travel is stopped by the perimetral ring 4 which is still in abutment between matrix 3 and punch 2 to closure mold 1 , due to the force determined by the pressure relief valve 73 .
- FIG. 5 shows the compression step end in which the mold is completely closed (matrix 3 in abutment on punch 2 ). At this point the molded part is cooled, with the mold still closed, and the cycle resumes.
- mold 1 according to the invention allows overcoming the drawbacks of the prior art.
- the particular geometry of the perimetral ring prevents the pressure of the molten material from pushing the ring itself outwards of the mold, ensuring the proper support of the perimetral ring during the injection of the material into the mold.
- the particular position of the perimetral ring closing the mold prevents the formation of triple junction points, and it effectively hides the junction lines on the piece.
- the perfect control of the perimetral ring when opening the mold prevents the ejection of the piece at the same time as the opening of the mold without risk of damage to the piece surface, even with a press of the type commonly available on the market.
Abstract
Description
- The present invention relates to a mold for injection-compression molding and a relative molding method.
- Injection-compression molding differs from the traditional molding process in the injection step, which takes place when the mold is open. The injection-compression process involves an initial step in which the mold has an initial opening before the injection step: this increases the volume of the cavity, which is partially filled by the molten material. The molten material is then compressed by the closing movement of the mold and the mold filling time is completed as a result. An alternative method involves filling the entire mold, and the compression step compensates only for the volumetric shrinkage of the molten material that solidifies. This is followed by the steps of cooling and extraction of the piece. In the injection-compression process, the final distribution in the mold, compaction and compensation of the shrinkage of the material occur by compression, by closing the mold through the movement of the press.
- In order to ensure the required tolerances on the mold closing, particularly with regard to thermal deformations induced to the mold by the same process, it is known to use perimetral rings, interposed between the upper portion (matrix) and the lower portion (punch) of the mold.
- However, this known solution also has some drawbacks:
-
- the pressure of the molten material can push the perimetral ring towards the outside of the mold, thus creating burrs on the piece;
- in some geometries, the construction of the perimetral ring is very expensive if not impossible since the perimetral ring must follow the geometrical features of the piece (such as wings and ribs) and in many cases, it creates (together with the matrix and punch) a triple junction point that is very difficult to form;
- the uncontrolled movement of the perimetral ring when opening the mold may damage (such as scratch) the surface of the piece.
- As described above, the prior art solutions have some drawbacks.
- In particular, to date, no reliable and cos-effective solutions are known that ensure the correct resting and support of the perimetral ring during the injection of the material into the mold.
- Moreover, to date, no perimetral ring solutions are known that allow preventing the presence of visible junction lines on the piece or on the outer edge of the piece.
- Moreover, to date, no reliable and cost-effective solutions are known that allow preventing the ejection of the piece at the opening by a system that ensures both the necessary tightness of the closure and the absence of residual forces when opening the mold.
- The need to solve the drawbacks cited with reference to the prior art is therefore felt.
- Further features and advantages of the present invention will appear more clearly from the following description of preferred non-limiting embodiments thereof, in which:
-
FIGS. 1-6 show schematic views of steps of a molding sequence according to the present invention; -
FIG. 7 shows a schematic top view of a perimetral ring according to the present invention; -
FIG. 8 shows a schematic view of the hydraulic circuit, integrated in the mold, for moving the perimetral ring; -
FIG. 9 shows an enlargement of a detail ofFIG. 5 , in which a perimetral ring is shown, in an embodiment example according to the present invention, in the closing step (between matrix and punch) of the mold; -
FIGS. 10-11 show further embodiment examples of the perimetral ring. - Elements or parts of elements in common o the embodiments described below are referred to with the same reference numerals.
- With reference to the above figures,
reference numeral 1 globally denotes a mold for injection compression molding (ICM). -
Mold 1 comprises apunch 2 and amatrix 3 suitable to close on thepunch 2 so as to delimit with this aninjection chamber 10 to contain the material to be injected.Matrix 3 andpunch 2 are axially movable between them with respect to an axial direction Y-Y of opening/closing ofmold 1. - As shown in the Figures,
mold 1 further comprises aperimetral ring 4, slidingly associated topunch 2 ormatrix 3, along the axial direction Y-Y, in which theperimetral ring 4 defines, together withmatrix 3 andpunch 2, the profile of theinjection chamber 10. - Mold 1 is characterised in that the closure between
matrix 3 andpunch 2 is accomplished using aperimetral ring 4 having a special shape of an interface wall withmatrix 3 above, or withpunch 2. - The
perimetral ring 4 comprises amatrix interface profile 43 intended to engage withmatrix 3, and apunch interface profile 42, intended to engage withpunch 2. - Advantageously, the
matrix interface profile 43 is equipped with a particular geometry suitable to generate a compression force ofring 4 towards the inside ofmold 1. - The
matrix interface profile 43 is convex, preferably convex polygonal. - In particular, the
matrix interface profile 43 comprises an inclinedupper thrust wall 443, on which aninclined plane 34 associated withmatrix 3 is engaged. - As shown in
FIG. 2 , in the closing step ofmold 1,matrix 3 pushes on theperimetral ring 4, and in particular on theupper thrust wall 443, thus generating a force F, substantially transversal to the axial direction Y-Y and directed towards the inside ofmold 1, which allows correctly retaining theperimetral ring 4, thus ensuring a correct support. - The
perimetral ring 4 comprises, between thematrix interface profile 43 and thepunch interface profile 42, aninner profile 41 which at least partially defines the profile of theinjection chamber 10. - The
perimetral ring 4 defines, with theinner profile 41, the profile of theinjection chamber 10 in all the molding process steps, i.e. in the mold closing step (FIG. 2 ), in the molten material injection step (FIG. 3 ), in the compression step (FIG. 4 ) up to the compression end step (FIG. 5 ). - The
perimetral ring 4 defines a portion of the profile of theinjection chamber 10 betweenmatrix 3 andpunch 2. Therefore, theperimetral ring 4 defines at least partially the profile of the piece, together withmatrix 3 andpunch 2. - In particular, the
inner profile 41 of theperimetral ring 4 defines at least partially the profile of the piece. - The
perimetral ring 4 is interposed betweenmatrix 3 and punch 2: such a solution allows obtaining double junction points on the piece. A double junction point is created in the mold by the coupling of two metal surfaces. - As shown in
FIG. 9 , a first double junction point (J1) is formed on the piece betweenpunch 2 andperimetral ring 4, and a second double junction point (J2) betweenperimetral ring 4 andmatrix 3. Such a solution therefore prevents the formation of a triple junction point on the piece (between punch, perimetral ring and matrix 3) of very difficult, if not impossible, execution. - In addition, the fact that at least a portion of the
perimetral ring 4 defines the profile of the piece allows producing pieces with rounded edges, as shown in FIG. 10. This solution is very important for pieces intended to come into contact with the user's skin. - In addition, the fact that at least a portion of the
perimetral ring 4 defines the profile of the piece allows to perform an aesthetic photoengraving or embossing treatment (T pattern in bas-relief made in negative on matrix 3), as shown inFIG. 11 . This solution, in which the piece has a wavy surface, is very important for pieces intended for the automotive industry, and in general for pieces intended to have an aesthetic value. - Even more advantageously, the
perimetral ring 4 defines at least partially thickness S of piece P, together withpunch 2. Such a solution allows effectively hiding the junction points on the piece. - In particular, the
inner profile 41 of theperimetral ring 4 defines, together withpunch 2, a first double junction point (J1) at thickness S of the piece. - Moreover, the
inner profile 41 of theperimetral ring 4 defines, together withmatrix 3, a second double junction point (J2) at an outer edge C of the piece. - As shown in
FIG. 9 , in fact, the first double junction point (J1) is placed at thickness S of the piece, and the second double junction point (J2) is placed at an outer edge C of the piece. The second double junction point (J2) derives from a flattening closure: it is therefore easy to make with good quality, and without being visible in the finished piece (being placed at an outer edge C of the piece). The first double junction point (J1) is instead by its geometric and technological nature difficult if not impossible to hide. However, the double junction point (J1) is also concealed and not visible to the user as it is placed at thickness S of the piece. Advantageously, therefore, there are no visible junction lines on the piece, which is very important for pieces intended to be aesthetic details. -
Mold 1 is also characterised in that the closing of theinjection chamber 10 takes place on theperimetral ring 4, a ring that defines together withpunch 2 thickness S of the piece, so that the juncion line is placed on the thickness (i.e. within thickness S) of the piece to be molded. -
Mold 1 is operated by axial movement means (not shown) ofmatrix 3 and/orpunch 2 to accomplish the opening and closing of the mold, hereinafter referred to as mold movement means. - Extraction mean 9 (not shown) act on
mold 1 adapted to extract the piece from the mold. -
Mold 1 is characterised in that theperimetral ring 4 is actuated by means ofhydraulic cylinders 51 actuated by ahydraulic circuit 7 capable of controlling the pressure in all process steps. Such ahydraulic circuit 7, which further comprises avalve assembly mold 1. -
Mold 1 comprises movement means 5 of theperimetral ring 4 adapted to carry out the advancement and retraction of the ring within the mold, hereafter referred to as ring movement means. - The ring movement means 5 comprise a hydraulic circuit 7 (shown in
FIG. 8 ) provided withactuating cylinders 51 activated/deactivated by hydraulic controls commonly found in injection presses (and referred to as radial). Usually, and disadvantageously, radials can only be used in standard presses when the mold is open. - In particular, the
hydraulic circuit 7 comprises a first hydraulic control 91 (referred to as radial one) and a second hydraulic control 92 (referred to as radial two). The radial or hydraulic control works with the following logic: if the hydraulic control is ON, the pressurised oil provides a constant pressure equal to the set pressure; if the control is OFF, the oil in the hydraulic circuit is free to flow towards a tank at atmospheric pressure. This last step is called ‘exhaust pressure’. - The
hydraulic circuit 7 for movingring 5 is thus connected and managed directly by the hydraulic control 91 (or radial one) of the press. - The
hydraulic circuit 7 comprises a firstnon-return valve 71, of the type with release controlled by pressure, directly controlled by radial two 92. - The
hydraulic circuit 7 further comprises apressure relief valve 73, which allows setting the pressures of the circuit and which can be calibrated between zero and the pressure of radial one. - The
hydraulic circuit 7 further comprises a secondnon-return valve 72. - The hydraulic circuit further comprises a
pressure gauge 76, to which avalve 75 is associated, for pressure control. - The
hydraulic circuit 7 comprises a series of T-unions 74. - The ring movement means 5 comprise a
plate 50 which can be lifted by means of theactuating cylinders 51 of the ancillary hydraulic circuit.Plate 50 is provided withaxial pins 52 connected to theperimetral ring 4. -
Plate 50, also referred to as “table”, is intended to ensure the coordination and parallelism of the movement (lifting and retraction) ofpins 52 and thus, of theperimetral ring 4. -
Plate 50 is provided with a constant preload, provided by the actuatingcylinders 51 of thehydraulic circuit 51 by means of thepressure relief valve 73. - Advantageously, the
hydraulic circuit 7 is integrated inmold 1 and is connected to the first hydraulic control 91 (referred to as radial one) and to the second hydraulic control 92 (referred to as radial two). This solution allows ensuring both the necessary seal of the closure and the absence of residual forces when openingmold 1, thus avoiding the ejection of the piece at the same time as the opening. -
FIGS. 1 to 7 show the operating diagram ofmold 1 and of theperimetral ring 4, moved by the ring movement means 5 and by thehydraulic circuit 7. -
FIG. 5 shows the compression step with completely closed mold, i.e. withmatrix 3 closed onpunch 2. Theperimetral ring 4, even if completely retracted due to the thrust ofmatrix 3, pushes on piece P: the actuatingcylinders 51 ofhydraulic circuit 7 are active and at constant pressure given by thepressure relief valve 73. - Once the cooling step has been completed, the piece is ready. From this moment, the radial controls (radial one and radial two) of the machine can be used. Radial two is pressurised: acting on the
non-return valve 71 it causes the release of pressure of the hydraulic circuit 7: the actuatingcylinders 51 drop to zero pressure and theperimetral ring 4 stops pushing on the piece. -
FIG. 6 shows the opening step of the open mold, i. e.matrix 3 raised with respect to punch 2, and theperimetral ring 4 in the retracted and at rest position (i.e. not in thrust). The actuatingcylinders 51, having lost pressure, do not push the piece during the opening step ofmold 1 so that it does not fall out before the picking robot arrives. The extraction of the piece is carried out by means of special extractors (not shown), while the pressure in thehydraulic circuit 7 for the movement of theperimetral ring 4 remains at zero until the extraction has taken place. -
FIG. 1 shows the mold still open but theperimetral ring 4 is now in the advanced position (or in thrust) for a new molding cycle. Radial one, connected directly to thering movement circuit 5, is put under pressure and theperimetral ring 4 moves forward. At this point, the pressure in radial one is reset to zero (and it could not be otherwise in a standard press), while in thehydraulic circuit 7, due to thenon-return valves - In
FIG. 2 ,mold 1 closes and theperimetral ring 4, pushed forward by the actuating cylinders, 51, retracts under the thrust ofmatrix 3. The retraction of theperimetral ring 4 reduces the volume of oil in theactuating cylinders 51, and in thehydraulic circuit 7 the constant pressure given by thepressure relief valve 73 remains. - At this point, the injection-compression step begins.
-
FIG. 3 shows the injection step of the molten material into theinjection chamber 10. -
FIG. 4 shows the compression step of the material.Mold 1 resumes closing, squeezing the molten material inside theinjection chamber 10. As shown inFIG. 8 , the molten material is pushed towards the edges of theinjection chamber 10 whenmold 1 is still open, but its travel is stopped by theperimetral ring 4 which is still in abutment betweenmatrix 3 and punch 2 toclosure mold 1, due to the force determined by thepressure relief valve 73. -
FIG. 5 shows the compression step end in which the mold is completely closed (matrix 3 in abutment on punch 2). At this point the molded part is cooled, with the mold still closed, and the cycle resumes. - As can be understood from the description,
mold 1 according to the invention allows overcoming the drawbacks of the prior art. - Advantageously, the particular geometry of the perimetral ring prevents the pressure of the molten material from pushing the ring itself outwards of the mold, ensuring the proper support of the perimetral ring during the injection of the material into the mold.
- Advantageously, moreover, the particular position of the perimetral ring closing the mold prevents the formation of triple junction points, and it effectively hides the junction lines on the piece.
- Advantageously, the perfect control of the perimetral ring when opening the mold prevents the ejection of the piece at the same time as the opening of the mold without risk of damage to the piece surface, even with a press of the type commonly available on the market.
- A man skilled in the art may make several changes and adjustments to the molds and molding methods described above in order to meet specific and incidental needs, all falling within the scope of protection defined in the following claims.
Claims (16)
Applications Claiming Priority (2)
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IT102016000116313 | 2016-11-17 | ||
IT102016000116313A IT201600116313A1 (en) | 2016-11-17 | 2016-11-17 | MOLD FOR INJECTION-COMPRESSION MOLDING |
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US20180133784A1 true US20180133784A1 (en) | 2018-05-17 |
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Family Applications (1)
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US15/816,527 Abandoned US20180133784A1 (en) | 2016-11-17 | 2017-11-17 | Mold for injection-compression molding |
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US (1) | US20180133784A1 (en) |
EP (1) | EP3323586B1 (en) |
ES (1) | ES2795875T3 (en) |
IT (1) | IT201600116313A1 (en) |
PT (1) | PT3323586T (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
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IT201800002814A1 (en) * | 2018-02-19 | 2019-08-19 | Umberto Nenna | MOLD FOR MAKING A HOLLOW BODY FOR INJECT-COMPRESSION AND METHOD OF MAKING THE HOLLOW BODY |
CN109228187B (en) * | 2018-10-08 | 2020-10-13 | 滁州市协众家电配件有限公司 | High-precision injection mold for refrigerator accessories |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6287488B1 (en) * | 1998-02-02 | 2001-09-11 | Thomas J. Dougherty | Method for injection molding of high quality parts |
US20040119204A1 (en) * | 2002-12-24 | 2004-06-24 | Sumitomo Chemical Company, Limited | Process for producing light transmitting plate |
US20060131788A1 (en) * | 2003-07-18 | 2006-06-22 | Sumitomo Heavy Industries, Ltd. | Molding method, mold for molding, molded product, and molding machine |
WO2016034990A1 (en) * | 2014-09-02 | 2016-03-10 | Plasdan - Automação E Sistemas, Lda. | Modular unit for injection-compression molding |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1182130A (en) * | 1967-08-04 | 1970-02-25 | Rolinx Ltd | Injection Moulding |
JPS5998812A (en) * | 1982-07-08 | 1984-06-07 | Toyo Seikan Kaisha Ltd | Production of plastic cap |
JP3944984B2 (en) * | 1998-01-05 | 2007-07-18 | 住友化学株式会社 | Mold for resin molding production |
JP6385831B2 (en) * | 2015-01-23 | 2018-09-05 | 住友重機械工業株式会社 | Injection molding machine |
-
2016
- 2016-11-17 IT IT102016000116313A patent/IT201600116313A1/en unknown
-
2017
- 2017-11-17 ES ES17202319T patent/ES2795875T3/en active Active
- 2017-11-17 EP EP17202319.4A patent/EP3323586B1/en active Active
- 2017-11-17 US US15/816,527 patent/US20180133784A1/en not_active Abandoned
- 2017-11-17 PT PT172023194T patent/PT3323586T/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6287488B1 (en) * | 1998-02-02 | 2001-09-11 | Thomas J. Dougherty | Method for injection molding of high quality parts |
US20040119204A1 (en) * | 2002-12-24 | 2004-06-24 | Sumitomo Chemical Company, Limited | Process for producing light transmitting plate |
US20060131788A1 (en) * | 2003-07-18 | 2006-06-22 | Sumitomo Heavy Industries, Ltd. | Molding method, mold for molding, molded product, and molding machine |
WO2016034990A1 (en) * | 2014-09-02 | 2016-03-10 | Plasdan - Automação E Sistemas, Lda. | Modular unit for injection-compression molding |
Also Published As
Publication number | Publication date |
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EP3323586B1 (en) | 2020-03-04 |
EP3323586A1 (en) | 2018-05-23 |
IT201600116313A1 (en) | 2018-05-17 |
ES2795875T3 (en) | 2020-11-25 |
PT3323586T (en) | 2020-05-11 |
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