Title of Invention	AN INJECTION MOULDING MOULD PART
Abstract	Injection moulding mould part (2) consisting of a mirror and a venting ring (7) that can be moved with respect thereto. A wear-resistant coating (12, 13) has been applied to the interface between the two parts that can be moved with respect to one another. This coating consists of hard metal based on tungsten with a minimum thickness of 0.01 mm and more particularly with a thickness of at least 0.1 mm. This coating is applied with an HVOF process (High Velocity Oxygen Fuel).

Title of Invention

AN INJECTION MOULDING MOULD PART

Abstract

Injection moulding mould part (2) consisting of a mirror and a venting ring (7) that can be moved with respect thereto. A wear-resistant coating (12, 13) has been applied to the interface between the two parts that can be moved with respect to one another. This coating consists of hard metal based on tungsten with a minimum thickness of 0.01 mm and more particularly with a thickness of at least 0.1 mm. This coating is applied with an HVOF process (High Velocity Oxygen Fuel).

Full Text	Injection wctvftAmfi Tnould part with wear-resistant coating The present invention relates to an injection moulding mould part comprising a base plate (minor) delimiting the injection mould cavity, around which a ring (vesting ring) that can be moved with respect thereto is arranged, which ring delimits within it an annular boundary surface of said injection mould cavity, which ring can be moved so as to reduce the volume of the injection mould cavity during injection moulding, the movable ring and the base plate being made of steel and at least one of the movable ring and the base plate being provided with a wear-resistant coating at the interface between said movable ring and the base plate, An injection moulding mould part of this type is generally known in the state of the art, The distance between the venting ring and mirror must be particularly small if not zero in order to prevent plastic getting in-between. However, the venting ring must move with respect to the mirror or base plate during each opening and closing movement To prevent wear, it is proposed in the state of the art to provide either the base plate or the venting ring with a wear resistant coating. This wear resistant coating is a PVD (Physical Vapour Deposition) coating, such as a DLC (Diamond Like Carbon) coating. It has been found that this coating is adequately wear-resistant, but that it cannot be guaranteed that the PVD coatings which is a few microns thick, will continue to adhere to the steel after prolonged use. The aim of the present invention is to provide a mxtror/venting ring combination with which a very large number of injection moulding cycles can be ensured without maintenance or replacement of components being necessary in lie interim* This aim is realised with an injection moulding mould part as described above wherein the wear-resistant coating comprises a coating based on tungsten with cobalt and has a thickness of at least 0.01 mm. According to the present invention, use is no longer made of a PVD coating a few microns thick. Instead of this, hard metal based on tungsten is used and the coating thickness is chosen to be appreciably greater, being at least 0.01 mm and more particularly at least 0.1 mm. More particularly, such a wear-resistant coating is applied to both the mirror and the venting ring. Experiments have shown that such a combination has a particularly long life and does not have the problems described above which are observed with PVD coatings. According to an advantageous embodiment, the wear-resistant coating contains except from tungsten cobalt and nickel. The steel used for the roiiror and the venting ring preferably contains at least 10 % chromium and is, of course, hardened. Although the wear-resistant coating can be applied to the venting ring and/or the mirror in any manner known in the state of the art, according to an advantageous embodiment this is applied using the method with the so-called BYOF process. HVOF (High Velocity Oxygen Fuel) is a process with which a hard metal product is introduced into a gas stream, which is generated by combining oxygen and fuel in a chamber located upstream* This powder is entrained by the gas through a delivery tube and projected onto the workpiece« The fuel used can be gas or liquid fuel, such as kerosene. Gas speeds of up to 3000 m/s are achievable. With such a process it is possible to apply both material based on tungsten and non-ferrous materials, such as types of bronze. According to the present invention, after applying the coating, the substrate treated in this way is finished by grinding in order to obtain the tight fit with the other component, being mirror or venting ring. Other methods for producing a hard metal coating are the application of hard metal foil and/or the use of hard metal sleeves. However it has been found that the bonding between the substrate and a hard metal is critical, and for this reason preference is given to Uie HVOF method described above. This adhesion is critical because of the close fit between the two intrinsically moving parts and the temperature fluctuations. The invention will be explained below with reference to an illustrative embodiment shown in the drawing. In the drawing; Fig. 1 shows, diagrammatically, an injection moulding mould in cross-section; and Fig 2 shows detail IE according to Fig. 1, In Fig. 1 an injection moulding mould is indicated by 1. This is in particular a mould for the injection of optical information carriers such as DVDs, CDs, etc. This mould must be fitted on an injection moulding machine. The mould consists of a mould part 3 and a mould part 2. Mould part 3 is provided with the ejector pin and the like, but this will not be discussed in detail below. Mould part 2 is coupled to the nozzle 4. On mould part 2 there is a mhxor 5, the mirror surface of which is indicated by 6. There is a venting ring 7 on the mirror 5. This ring is fixed to mould part 2 by means of bolts. There is a free space through which the venting ring 7 can be displaced with respect to the mirror 5 > The inner ring surface of the venting ring 7 is indicated by 8. The mould cavity 9 is delimited by the mirror surface 6 and the part of the jacket surface 8 that protrudes beyond the mirror surface 6. The venting ring moves relative to the mirror 5 during each injection cycle. This occurs for a wide variety of reasons. One of these is the post-pressing of the plastic (stamping) so as to obtain better correspondence between the stamper and the part produced by injection moulding. The interface between the venting ring 7 and the mirror 5 is subjected to particularly severe stress. After all, the movement described above takes place during each cycle. The fit between the two parts must be close in order to prevent plastic material penetrating into the gap between them during injection. In older to prevent problems with regard to wear at the interface, it is proposed according to the present invention, as shown in Fig. 2, to apply a wear-resistant coating 13 and 12, respectively, to both the venting ring 7 and the mirror 5. This wear-resistant coating consists of a hard metal based on tungsten and is at least 0.1 mm thick. Apart from tungsten, nickel and cobalt, for example, are present as alloying elements. It has been &uud that as a result of the use of such a wear-resistant coating there is stiU no damage or change in tolerance between venting ring 7 and mirror 5 even after many million cycles. The coatings 12 and 13 are preferably applied with the aid of the HVOF method. Although the invention has been described above with reference to a preferred embodiment; it will be understood by those skilled in the art that numerous variants are possible that are obvious after reading the above description and fall within the scope of the appended claims. Claims 1. Injection moulding mould part (2) comprising a base plate (5) (mirror) delimiting the injection mould cavity (9), around which a ring (7) (venting ring) that can be moved with respect thereto is arranged, which ring delimits within it an annular boundary surface (8) of said injection mould cavity (9), which ring can be moved so as to reduce the volume of the injection mould cavity during injection moulding, the movable ring and the base plate being made of steel and at least one of the movable ring and the base plate being provided with a wear-resistant coating at the interface between said movable ring and the base plate, characterised in that the wear-resistant coating (12,13) comprises a coating based on tungsten with cobalt and has a thickness of at least 0.01 mm. 2. Injection moulding mould part according to Claim 1, wherein said coating comprises a foil. 3. Injection moulding mould part according to Claim 1 or 2, wherein said wear-resistant coating is applied both to the movable ring and the base plate. 4. Injection moulding mould part according to one of the preceding claims, wherein the wear-resistant coating is applied to said base plate and extends as far as the boundary surface (6) thereof. 5. Injection moulding mould part according to one of the preceding claims, wherein said wear-resistant coating contains nickel and/or chromium. 6. Injection moulding mould part according to one of the preceding claims, wherein said steel contains at least 10 % chromium. 7. Injection moulding mould part according to one of the preceding claims, wherein said wear-resistant coating is at least 0.1 mm thick. 8. Injection moulding mould part according to one of the preceding claims, wherein said movable ring is fitted around said base plate such that tibiere is essentially no play. 9. Method for applying a wear-resistant coating to a boundary surface of a component of an injection moulding mould part, which injection moulding mould part comprises a base plate (5) delimiting the injection mould cavity, around which base plate a ring (7) is arranged, which ring determines the boundary surface inside it, which ring can be moved so as to reduce the volume of the injection mould cavity during injection moulding, the movable ring and the base plate being made of steel, characterised in that the application comprises application of a wear-resistant coating based on tungsten with a minimum coating thickness of 0.01 mm by means of an HVOF process. 10. Method according to Claim 9, wherein this coating is based on tungsten. 1L Method according to Claim 9, wherein said coating is based on a non-ferrous metal. 12. Method according to Claim 9> wherein, after applying said wear-resistant coating, said coating is finished by grinding.

Full Text

Injection wctvftAmfi Tnould part with wear-resistant coating
The present invention relates to an injection moulding mould part comprising a base plate (minor) delimiting the injection mould cavity, around which a ring (vesting ring) that can be moved with respect thereto is arranged, which ring delimits within it an annular boundary surface of said injection mould cavity, which ring can be moved so as to reduce the volume of the injection mould cavity during injection moulding, the movable ring and the base plate being made of steel and at least one of the movable ring and the base plate being provided with a wear-resistant coating at the interface between said movable ring and the base plate,
An injection moulding mould part of this type is generally known in the state of the art, The distance between the venting ring and mirror must be particularly small if not zero in order to prevent plastic getting in-between. However, the venting ring must move with respect to the mirror or base plate during each opening and closing movement
To prevent wear, it is proposed in the state of the art to provide either the base plate or the venting ring with a wear resistant coating. This wear resistant coating is a PVD (Physical Vapour Deposition) coating, such as a DLC (Diamond Like Carbon) coating.
It has been found that this coating is adequately wear-resistant, but that it cannot be guaranteed that the PVD coatings which is a few microns thick, will continue to adhere to the steel after prolonged use.
The aim of the present invention is to provide a mxtror/venting ring combination with which a very large number of injection moulding cycles can be ensured without maintenance or replacement of components being necessary in lie interim*
This aim is realised with an injection moulding mould part as described above wherein the wear-resistant coating comprises a coating based on tungsten with cobalt and has a thickness of at least 0.01 mm.
According to the present invention, use is no longer made of a PVD coating a few microns thick. Instead of this, hard metal based on tungsten is used and the coating thickness is chosen to be appreciably greater, being at least 0.01 mm and more particularly at least 0.1 mm. More particularly, such a wear-resistant coating is applied to both the mirror and the venting ring. Experiments have shown that such a combination has a particularly long life and does not have the problems described above which are observed with PVD coatings.

According to an advantageous embodiment, the wear-resistant coating contains except from tungsten cobalt and nickel.
The steel used for the roiiror and the venting ring preferably contains at least 10 % chromium and is, of course, hardened.
Although the wear-resistant coating can be applied to the venting ring and/or the mirror in any manner known in the state of the art, according to an advantageous embodiment this is applied using the method with the so-called BYOF process. HVOF (High Velocity Oxygen Fuel) is a process with which a hard metal product is introduced into a gas stream, which is generated by combining oxygen and fuel in a chamber located upstream* This powder is entrained by the gas through a delivery tube and projected onto the workpiece« The fuel used can be gas or liquid fuel, such as kerosene. Gas speeds of up to 3000 m/s are achievable. With such a process it is possible to apply both material based on tungsten and non-ferrous materials, such as types of bronze.
According to the present invention, after applying the coating, the substrate treated in this way is finished by grinding in order to obtain the tight fit with the other component, being mirror or venting ring.
Other methods for producing a hard metal coating are the application of hard metal foil and/or the use of hard metal sleeves. However it has been found that the bonding between the substrate and a hard metal is critical, and for this reason preference is given to Uie HVOF method described above. This adhesion is critical because of the close fit between the two intrinsically moving parts and the temperature fluctuations.
The invention will be explained below with reference to an illustrative embodiment shown in the drawing. In the drawing;
Fig. 1 shows, diagrammatically, an injection moulding mould in cross-section; and
Fig 2 shows detail IE according to Fig. 1,
In Fig. 1 an injection moulding mould is indicated by 1. This is in particular a mould for the injection of optical information carriers such as DVDs, CDs, etc. This mould must be fitted on an injection moulding machine. The mould consists of a mould part 3 and a mould part 2. Mould part 3 is provided with the ejector pin and the like, but this will not be discussed in detail below.
Mould part 2 is coupled to the nozzle 4. On mould part 2 there is a mhxor 5, the mirror surface of which is indicated by 6.
There is a venting ring 7 on the mirror 5. This ring is fixed to mould part 2 by means

of bolts. There is a free space through which the venting ring 7 can be displaced with respect to the mirror 5 > The inner ring surface of the venting ring 7 is indicated by 8.
The mould cavity 9 is delimited by the mirror surface 6 and the part of the jacket surface 8 that protrudes beyond the mirror surface 6.
The venting ring moves relative to the mirror 5 during each injection cycle. This occurs for a wide variety of reasons. One of these is the post-pressing of the plastic (stamping) so as to obtain better correspondence between the stamper and the part produced by injection moulding.
The interface between the venting ring 7 and the mirror 5 is subjected to particularly severe stress. After all, the movement described above takes place during each cycle. The fit between the two parts must be close in order to prevent plastic material penetrating into the gap between them during injection.
In older to prevent problems with regard to wear at the interface, it is proposed according to the present invention, as shown in Fig. 2, to apply a wear-resistant coating 13 and 12, respectively, to both the venting ring 7 and the mirror 5. This wear-resistant coating consists of a hard metal based on tungsten and is at least 0.1 mm thick. Apart from tungsten, nickel and cobalt, for example, are present as alloying elements. It has been &uud that as a result of the use of such a wear-resistant coating there is stiU no damage or change in tolerance between venting ring 7 and mirror 5 even after many million cycles.
The coatings 12 and 13 are preferably applied with the aid of the HVOF method.
Although the invention has been described above with reference to a preferred embodiment; it will be understood by those skilled in the art that numerous variants are possible that are obvious after reading the above description and fall within the scope of the appended claims.

Claims
1. Injection moulding mould part (2) comprising a base plate (5) (mirror) delimiting the injection mould cavity (9), around which a ring (7) (venting ring) that can be moved with respect thereto is arranged, which ring delimits within it an annular boundary surface (8) of said injection mould cavity (9), which ring can be moved so as to reduce the volume of the injection mould cavity during injection moulding, the movable ring and the base plate being made of steel and at least one of the movable ring and the base plate being provided with a wear-resistant coating at the interface between said movable ring and the base plate, characterised in that the wear-resistant coating (12,13) comprises a coating based on tungsten with cobalt and has a thickness of at least 0.01 mm.
2. Injection moulding mould part according to Claim 1, wherein said coating comprises a foil.
3. Injection moulding mould part according to Claim 1 or 2, wherein said wear-resistant coating is applied both to the movable ring and the base plate.
4. Injection moulding mould part according to one of the preceding claims, wherein the wear-resistant coating is applied to said base plate and extends as far as the boundary surface (6) thereof.
5. Injection moulding mould part according to one of the preceding claims, wherein said wear-resistant coating contains nickel and/or chromium.
6. Injection moulding mould part according to one of the preceding claims, wherein said steel contains at least 10 % chromium.
7. Injection moulding mould part according to one of the preceding claims, wherein said wear-resistant coating is at least 0.1 mm thick.
8. Injection moulding mould part according to one of the preceding claims, wherein said movable ring is fitted around said base plate such that tibiere is essentially no play.

9. Method for applying a wear-resistant coating to a boundary surface of a component of an
injection moulding mould part, which injection moulding mould part comprises a base
plate (5) delimiting the injection mould cavity, around which base plate a ring (7) is
arranged, which ring determines the boundary surface inside it, which ring can be moved so
as to reduce the volume of the injection mould cavity during injection moulding, the
movable ring and the base plate being made of steel, characterised in that the application
comprises application of a wear-resistant coating based on tungsten with a minimum
coating thickness of 0.01 mm by means of an HVOF process.
10. Method according to Claim 9, wherein this coating is based on tungsten.
1L Method according to Claim 9, wherein said coating is based on a non-ferrous metal.
12. Method according to Claim 9> wherein, after applying said wear-resistant coating, said coating is finished by grinding.

Documents:

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2237-chenp-2005 abstract-duplicate.pdf

2237-chenp-2005 claims-duplicate.pdf

2237-chenp-2005 description (complete)-duplicate.pdf

2237-chenp-2005 drawings-duplicate.pdf

2237-chenp-2005-abstract.pdf

2237-chenp-2005-claims.pdf

2237-chenp-2005-correspondnece-others.pdf

2237-chenp-2005-correspondnece-po.pdf

2237-chenp-2005-description(complete).pdf

2237-chenp-2005-drawings.pdf

2237-chenp-2005-form 1.pdf

2237-chenp-2005-form 18.pdf

2237-chenp-2005-form 3.pdf

2237-chenp-2005-form 5.pdf

2237-chenp-2005-pct.pdf

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Patent Number

223312

Indian Patent Application Number

2237/CHENP/2005

PG Journal Number

47/2008

Publication Date

21-Nov-2008

Grant Date

09-Sep-2008

Date of Filing

12-Sep-2005

Name of Patentee

AXXICON MOULDS EINDHOVEN B.V.

Applicant Address

EKKERSRIJT 7501, NL-5692 HN SON,

Inventors:

#	Inventor's Name	Inventor's Address
1	TIJL, HERM, ADRIANUS	UDINESTRAAT 2, NL-5632 RW EINDHOVEN,
2	VAN RIJT, MARCELIS, JOHANNES	WINSTON 22, NL-5721 TS ASTEN,
3	VAN DE MORTEL, HENDRICUS, JOHANNA, WIJNANDA	KEEPSTRAAT 4, NL-5704 LH HELMOND,

PCT International Classification Number

B29C45/26

PCT International Application Number

PCT/NL04/00181

PCT International Filing date

2004-03-12

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	1022910	2003-03-12	Netherlands