WO2001005536A1

WO2001005536A1 - Mould manufacture

Info

Publication number: WO2001005536A1
Application number: PCT/EP2000/006954
Authority: WO
Inventors: Dirk-Olaf Leimann
Original assignee: Hansen Transmissions International Bv
Priority date: 1999-07-20
Filing date: 2000-07-20
Publication date: 2001-01-25
Also published as: GB2352199B; AU6696600A; GB9916832D0; GB2352199A; GB0017774D0

Abstract

For the manufacture of a mould such as a sand mould for casting metal products use is made of a primary pattern member (11) a surface of which is used to create a first part of a required mould shape, and a secondary pattern member (13) carried by and movable relative to said primary pattern member, said secondary pattern member having a surface which is used to create another part of a required mould shape, said primary pattern member being of a shape removable from a mould in a first direction (B) without damage to the mould, said secondary pattern member being movable in unison with the primary pattern member in said first direction (B) and being selectively moveable relative to the primary pattern member in a second direction (A) which is inclined relative to said first direction, the secondary pattern member being movable to an extended position for an operation of creating a required mould shape and movable to a retracted position after a required mould shape has been created and prior to removal of the primary pattern member from a mould. The secondary pattern member may be moved to an extended position either before or after mould material has been shaped by said surface of the primary pattern member and thereby to enable a surface of the secondary pattern member to create another part of a required mould shape, before the secondary pattern member is moved to a retracted position.

Description

"MOULD MANUFACTURE"

This invention relates to a method of and apparatus for the manufacture of a mould and in particular, although not exclusively, to the manufacture of a mould for use in producing a substantially rigid product by a casting technique.

For the manufacture of cast metal products it is well known to make use of a sand mould. To form a sand mould to the required shape it is usual to employ a pre-shaped pattern piece which is either pressed into a volume of sand to create a desired mould shape, or used as a base or core onto or around which sand is compacted. Whilst that technique is successful and economical for creating moulds required for the manufacture of products of a simple shape and can be employed both to create outer moulds that define the outer surface shape of a product as well as to core moulds which define an inner surface shape of a product, it is not easily and economically employed for the manufacture of moulds of a complex shape such as a shape having undercut regions.

In the case of manufacture of a mould having an undercut region, which makes impossible the removal of a pattern piece in a single operation, it is known to use a plurality of individual pattern pieces which are removed in sequence following shaping of the mould. That sequential operation however is time consuming and difficult to employ economically as part of an automatic or semi-automatic procedure for the manufacture of a mould.

The present invention seeks to provide a method of and apparatus for the manufacture of a mould which is more suitable for use as part of an automatic or semi-automatic procedure.

In accordance with one aspect of the present invention apparatus for the manufacture of a mould comprises a primary pattern member a surface of which is used to create a first part of a required mould shape, and a secondary pattern member carried by and movable relative to said primary pattern member, said secondary pattern member having a surface which is used to create another part of a required mould shape, said primary pattern member being of a shape removable from a mould in a first direction without damage to the mould and said secondary pattern member being movable in said first direction in unison with the primary pattern member when the primary pattern member moves in said first direction, said secondary pattern member being selectively movable relative to the primary pattern member in a second direction which is inclined relative to said first direction, and actuation means whereby the secondary pattern member may be moved to an extended position for an operation of creating a required mould shape and may be moved to a retracted position after a required mould shape has been created and prior to removal of the primary pattern member from a mould.

In accordance with another aspect of the present invention a method for the manufacture of a mould comprises providing a multi-part pattern member comprising a primary pattern member having a surface at least a part of which is used to create a first part of a required mould shape and a secondary pattern member having a surface which is used to create another part of a required mould shape, said primary pattern member being of a shape removable from a mould in a first direction without damage to the mould and said secondary pattern member being movable in said first direction in unison with the primary pattern member when the primary pattern member moves in said first direction, and the secondary pattern member being selectively movable relative to the primary pattern member in a second direction which is inclined relative to said first direction, said method comprising moving the secondary pattern member to an extended position either before or after mould material has been shaped by said surface of the primary pattern member and thereby to enable a surface of the secondary pattern member to create another part of a required mould shape, moving the secondary pattern member to a retracted position, and then removing the primary pattern member from the mould in said first direction.

The second direction of movement of the secondary pattern member may be substantially perpendicular relative to the first direction of movement of the primary pattern member.

The primary pattern member may comprise a cavity into and outwards from which the secondary pattern member is movable. The secondary member preferably can be retracted to a position at which it lies wholly within said cavity, and optionally with an exposed surface lying substantially flush with an adjacent mould shaping surface region of the primary pattern member. The actuation means may be an integral part of a secondary pattern member, or separate. The actuation means may be operable by hand, or, for example, by mechanical, electromechanical or hydraulic equipment.

The secondary pattern member may be of a unitary construction or may comprise two or more sections. It may comprise two sections a first of which is movable in said second direction of movement and the second of which is movable in a third direction. Optionally said second section may be movable in two directions each of which may be inclined (which term includes perpendicular) relative to said first direction, and one of said two directions may be parallel with said second direction in which said first of the two sections of the secondary pattern member is movable. The first section may comprise a guide surface inclined relative to said second direction to guide the second section for movement in a third direction relative to said first and second directions. The primary pattern member may comprise a cavity with a mouth region that is inclined and acts as a closure seat for the guide surface of the first section when said first section is in a retracted condition.

First and second sections of a secondary pattern member may comprise interlockable formations whereby movement of the second section to a retracted condition causes movement of the first section, at least after an initial period of movement of the second section.

At least a part of the secondary pattern member may be flexible. It may be movable in a guide which causes it to flex when the secondary member moves between extended and retracted positions. It may be guided by a cavity in the primary pattern member and having a non-linear shape in the direction of movement.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:

Figure la is a part section of part of a mould pattern in accordance with one embodiment of the invention; Figure lb is a view in the direction of arrow A of Figure la; Figure 2 is a side view of part of a mould pattern in accordance with another embodiment of the invention; Figures 3a-3d are part sections on the line A-A of Figure 2 with components in successive positions; Figure 4 is a view similar to that of Figure 3 of another embodiment and showing sequences for two directions of movement; Figure 5 is a part section of a mould pattern in accordance with a further embodiment of the invention, and Figure 6 shows another secondary pattern member.

With reference to Figures la and lb, a pattern piece 10 for shaping a sand mould into which molten metal is to be cast comprises a primary pattern member in the form of a body 11 having a cavity 12 in which a secondary pattern member in the form of a block 13 is slideable in the direction of arrow A. In use the pattern piece is removed from mould material in direction B which is perpendicular to A.

Figures 2 and 3 show a pattern body 20 having a recess 21 and two secondary pattern members 22,23 movable in a cavity 24 of the body 20.

Member 22 has a height "h" as viewed in Figure 3 which is equal to the height of the cavity, and comprises a guide surface 25.

Member 23 has a forward guide surface 26 which can slide over surface 25. Member 23 also has a rear guide surface 27 which can slide over a guide surface 28 of the body at the mouth region of the cavity 24.

In use, to retract from the position of Figure 3a, the member 22 is moved into the cavity, initially in a direction parallel with the inclination of the guide surfaces and then with the length direction of the cavity 24, as shown at Figures 3b and 3c. Finally the member 23 is retracted to the position shown at Figure 3d.

The retracted condition of the members 22,23 allows, in use, the pattern body 20 to be withdrawn from a mould, for example, in the direction of arrow C without any damage to mould material present in the recess 21.

Figure 4 shows a modified form of the embodiment of Figures 2 and 3 in which the two secondary pattern members 40,41 are provided with inter- engageable shoulders 42,43. Referring to the left-hand views, at the fourth down position of a retraction sequence the inner member 41 acts to retract the outer member 40 in consequence of engagement of the shoulder 42 with shoulder 43 of the outer member. In the reverse sequence of extension, as shown by the right-hand views, movement of the inner member urges the outer member outwards from the cavity 24 until member 40 reaches a stop (not shown). Member 41 then rides up over the inclined ramp surface of member 40 to reach the position shown in the top view of Figure 4. To allow the shoulders 42,43 to ride over one-another during the outwards movement the cavity is provided with relieved regions 44,45.

Figure 5 shows use of a flexible second pattern member which is in the form of a flexible plastics rod 50 slideable in a passage 51 in the body of a primary pattern member 52. The end 53 of the rod can lie extended to create a cylindrical cavity 55 in a sand mould 54, and then be retracted to lie wholly in the passage 51 to allow the body 52 to be removed from the mould 54 in the direction of arrow F without damage to the cylindrical cavity 55.

Figure 6 shows a flexible pattern member 60 in the form of a flexible plastics strip of a rectangular cross-section.

Claims

CLAIMS:

1. Method for the manufacture of a mould comprising providing a multipart pattern member comprising a primary pattern member (11) having a surface at least a part of which is used to create a first part of a required mould shape and a secondary pattern member (13) having a surface which is used to create another part of a required mould shape, said primary pattern member being of a shape removable from a mould in a first direction (B) without damage to the mould and said secondary pattern member being movable in said first direction in unison with the primary pattern member when the primary pattern member moves in said first direction,and the secondary pattern member being selectively movable relative to the primary pattern member in a second direction (A) which is inclined relative to said first direction, said method comprising moving the secondary pattern member to an extended position either before or after mould material has been shaped by said surface of the primary pattern member and thereby to enable a surface of the secondary pattern member to create another part of a required mould shape, moving the secondary pattern member to a retracted position, and then removing the primary pattern member from the mould in said first direction.

2. Method according to claim 1, wherein said second direction (A) of movement of the secondary pattern member (13) is substantially perpendicular relative to said first direction (B) of movement of the primary pattern member (11).

3. Method according to claim 1 or claim 2, wherein the secondary pattern member comprises two sections (22,23) a second (22) of which is moved in two directions each inclined relative to said first direction for changing between extended and retracted positions.

4. Method according to claim 3, wherein first and second sections (40,41) of the secondary pattern member are provided with interlockable formations (42,43) and the first section (40) is moved to a retracted condition by action of the interlocking formations and movement of the second section (41) to a retracted condition.

5. Method according to any one of the preceding claims, wherein the secondary pattern member is moved to a retracted condition at which an exposed surface thereof lies substantially flush with an adjacent mould shaping surface region of the primary pattern member before removal from the mould.

6. Method according to any one of the preceding claims, wherein the secondary pattern member (13) is located in a cavity (12) provided by the primary pattern member (11) and is moved in said cavity to lie either in said extended position or said retracted position.

7. Method according to any one of the preceding claims, wherein the secondary pattern member is moved to an extended position after mould material has been shaped by a surface of the primary pattern member.

8. Method according to any one of the preceding claims, wherein use is made of a secondary pattern member (50) at least a part of which is flexible.

9. Apparatus for the manufacture of a mould comprising a primary pattern member a surface of which is used to create a first part of a required mould shape, and a secondary pattern member (13) carried by and movable relative to said primary pattern member, said secondary pattern member having a surface which is used to create another part of a required mould shape, said primary pattern member being of a shape removable from a mould in a first direction (B) without damage to the mould and said secondary pattern member being movable in said first direction in unison with the primary pattern member when the primary pattern member moves in said first direction, said secondary pattern member (13) being selectively movable relative to the primary pattern member in a second direction (A) which is inclined relative to said first direction, and actuation means whereby the secondary pattern member may be moved to an extended position for an operation of creating a required mould shape and may be moved to a retracted position after a required mould shape has been created and prior to removal of the primary pattern member from a mould.

10. Apparatus according to claim 9, wherein means is provided for movement of the secondary pattern member (13) in a direction substantially perpendicular relative to said first direction (B) of movement of the primary pattern member ( 11 ) .

11. Apparatus according to claim 9 or claim 10, wherein the primary pattern member (11) comprises a cavity (12) into and outwards from which the secondary pattern member (13) is movable.

12. Apparatus according to any one of claims 9 to 11, wherein the secondary pattern member has an exposed surface which lies substantially flush with an adjacent mould shaping surface region of the primary pattern member when the secondary pattern member is at a retracted position.

13. Apparatus according to any one of claims 9 to 12, wherein the secondary pattern member comprises at least two sections a second of which is movable in two directions each inclined relative to said first direction.

14. Apparatus according to claim 13, wherein a first (23) of said sections is movable relative to the primary pattern member substantially only in said second direction (A).

15. Apparatus according to claim 14, wherein said second direction of movement of a first (23) of said sections is parallel with one of the directions of movement of said second (22) of the at least two sections of the secondary pattern member.

16. Apparatus according to any one of claims 13 to 15, wherein the primary pattern member (20) comprises a cavity (24) in which the secondary pattern member (22,23) is movable and a mouth region of said cavity comprises a guide surface (28) inclined relative to said second direction to act as a guide surface for a second (22) of said two sections.

17. Apparatus according to claim 16, wherein the guide surface (28) is adapted to act as a closure seat for contact by a first section (22) of the secondary pattern member when in a retracted condition.

18. Apparatus according to any one of claims 13 to 17, wherein the first section (23) of the secondary pattern member comprises a guide surface (28) inclined relative to said second direction and adapted to guide the second section (22) for movement in a third direction inclined relative to said first and second directions.

19. Apparatus according to any one of claims 9 to 18, wherein at least a part of the secondary pattern member (50) is flexible and, in use, is arranged to flex when moving between extended and retracted positions.