WO2001023123A1

WO2001023123A1 - Improved casting apparatus

Info

Publication number: WO2001023123A1
Application number: PCT/EP1999/007410
Authority: WO
Inventors: Jacques Guyon
Original assignee: Federal-Mogul Chasseneuil Sas
Priority date: 1998-04-01
Filing date: 1999-09-30
Publication date: 2001-04-05
Also published as: GB2335876A; GB9806878D0

Abstract

A casting apparatus is described comprising first and second half core moulds, a vertically displaceable centre core located between the first and second half core moulds, a ring core located about the half core molds to limit the horizontal separation of the half core moulds, and first and second outer half moulds, characterised in that the first half mould is static and the second half mould is provided with means to displace it towards and away from the first half mould.

Description

Improved Casting Apparatus

The present invention relates to an improved casting apparatus and to a method of using the apparatus to manufacture a plurality of articles. The method has particular, though not exclusive, utility in the manufacture of pistons for use in internal combustion engines.

A casting apparatus is known for the manufacture of pistons for use in internal combustion engines. A piston cavity into which molten material is to be cast is defined by a casting apparatus comprising a pair of half core moulds, a vertically displaceable centre core located between the pair of half core moulds, a ring core located about the half core moulds to limit the horizontal separation of the half core moulds, and a pair of outer half moulds. Each of the moulds, the core moulds and the outer half moulds, are individually horizontally displaceable. In use the cavity is formed and molten material is introduced into the cavity to form a cast body and allowed to solidify. When the cast body has sufficient integrity, the centre core is withdrawn to allow each of the core moulds to be displaced towards one another. Each of the outer half moulds is then displaced away from the cast body until sufficient clearance is provided to allow the cast body to be vertically removed from the casting apparatus.

However, the use of such an apparatus presents a number of problems. Each of the moulds must be provided with means to enable the mould to be displaced. If any one of the individual means becomes inoperable, the casting apparatus cannot be used until repairs have been effected. Further, space must be provided to allow the moulds to move. In particular, space must be provided within the casting apparatus to allow the outer half moulds to be moved sufficiently far away from the cast body to allow the cast body to be removed from the casting apparatus. Accordingly there is a need for a casting apparatus, that in respect to each cast body manufactured, requires fewer moving parts leading to a decreased risk of stoppages and occupies less space leading to a moie productive use of factory space. According to the present invention, we provide a casting apparatus comprising means defining a casting cavity at a first location in which a cast body is manufactured, the means defining the casting cavity comprising first and second half core moulds, a vertically displaceable centre core located between the first and second half core moulds, a ring core located about the half core moulds to limit the horizontal separation of the half core moulds, and first and second outer half moulds, characterised in that displacement means are provided to displace the cast body to a second location in the casting to the first location to allow removal of the cast body.

Preferably the second outer half mould remains stationary throughout a casting cycle.

Preferably, movement of the half core moulds is determined by movement of the second outer half mould. Preferably or alternatively, the second outer half mould is provided with displacement means to displace it towards and away from the first outer half mould.

Preferably, the displacement means comprises hydraulically or pneumatically operated piston means.

Preferably the ring core includes a circumferential bead which is adapted for engagement with complementary recesses formed on the first and the second outer half moulds.

Preferably the first outer half mould is secured to a fixed platen and the second outer half mould is secured to a moveable platen. More preferably the ring core includes a radially outwardly extending flange having a shoulder and each moveable platen is provided on a lower surface with a recess, the recesses and the shoulder being adapted to abut one another.

Such a casting apparatus, in respect to each cast body manufactured, requires only means to displace one of the moulds horizontally in the casting assembly. Accordingly space in the casting apparatus is required only for one such means.

According to a second aspect of the invention a method of manufacture of a cast body using a casting apparatus according to the first aspect of the invention comprises the steps of i) forming a casting cavity at a first location within the casting apparatus; ii) introducing molten material to the casting cavity to form a cast body; iii) allowing the cast body to cool; and iv) removing the cast body from the casting apparatus; characterised in that after the cast body has achieved sufficient integrity it is moved to a second location within the casting apparatus at which location it can be removed from the casting apparatus.

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

Figures 1 to 4 show in vertical section the steps in the operation of a known apparatus;

Figure 5 shows a plan view of the apparatus shown in Figures 1 to 4;

Figure 6 shows in vertical section a part of an apparatus according to the present invention;

Figure 7 shows a plan view of the apparatus shown in Figure 6;

Figure 8 shows in schematic form a side view of the means for moving a casting apparatus according to a second embodiment of the present invention in a first position;

Figure 9 shows in schematic form a plan view of the apparatus in the position shown in Figure 8;

Figure 10 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in a second position;

Figure 11 shows in schematic form a plan view of the apparatus in the position shown in Figure 10;

Figure 12 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in a third position; Figure 13 shows in schematic form a plan view of the apparatus in the position shown in Figure 12;

Figure 14 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in a forth position;

Figure 15 shows in schematic form a plan view of the apparatus in the position shown in Figure 14;

Figure 16 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in a fifth position;

Figure 17 shows in schematic form a plan view of the apparatus in the position shown in Figure 16;

Figure 18 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in a sixth position;

Figure 19 shows in schematic form a plan view of the apparatus in the position shown in Figure 18;

Figure 20 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in a seventh position;

Figure 21 shows in schematic form a plan view of the apparatus in the position shown in Figure 20;

Figure 22 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in an eighth position; Figure 23 shows in schematic form a side view of the means for moving a casting apparatus according to the second embodiment of the present invention in a ninth position; and

Figure 24 shows in schematic form a plan view of the apparatus in the position shown in Figure 23.

Reference is first made to Figures 1 to 4, which illustrate a known casting apparatus 1. The apparatus is generally symmetrical about an axis 2. The axis of symmetry 2 is coincident with the vertical axis of a vertically moveable centre core 3. The centre core 3 extends through a mounting base 4.

The casting apparatus 1 generally comprises first and second half core moulds 8,18, the vertically displaceable centre core 3 being located between the first and second half core moulds, a ring core 9 located about the half core moulds 8,18 to limit the horizontal separation of the half core moulds, and first and second outer half moulds 5,15.

Each half core mould 8,18 is mounted on a separate moveable platen 25,35. Each half core mould 8,18 is generally 'L' shaped and comprises a horizontal member by which each half core mould 8,18 is secured to each moveable platen 25,35 and a vertical member comprising a lower broader portion and an upper thinner portion. At an upper end of the upper thinner portion of the half core mould 8,18, there is an enlarged bulbous portion.

The ring core 9 is located about the broader portion of the vertical members of the half core moulds, and rests upon the horizontal members of the half core moulds. The ring core 9 is general cylindrical comprising a generally upright wall 22, a radially outwardly extending flange 23 at a lower end of the wall and a protrusion or bead 21 about an upper end of the wall 2. When the half mould assemblies are held in a retracted position, the broader lower portions of the vertical member of the half core mould^'s abut the inner surface of the wall 22 of the ring core 9. The flange 23 of the ring core 9 forms a shoulder 24.

Each outer half mould 5,15 is mounted on a separate moveable platen 27,37. Each outer half mould 5,15 is generally half cylindrical in form and includes a recess 20,30 extending around the periphery of the mould and a generally cylindrical protrusion 33,34 extending radially inward from the outer half mould 5,15. The underside of each moveable platen 27,37 is provided with a recess 31,32.

Means 6,16 defining a half orifice are located above the outer half mould 5,15.

Mould clamping means are provided for displacing each of the moulds, the half core moulds and the outer half moulds. Conveniently each of the mould clamping means comprise pistons 10,11,12,13 connected to a moveable platen 25,27,35,37 by a piston rod 26,28,36,38. In this way each moveable platen 25,27,35,37 can be displaced between an advanced and a retracted position as required.

With the associated moveable platens 26,36 in the advanced position, the outer half moulds 5,15 on either side of the axis of symmetry 2 abut one another, and the horizontal member of each moveable platen 26,36 extends beneath the ring core 9. In particular, the bead 21 of the ring core 9 is located within the recesses 20,30 of the outer half moulds 5,15. At the same time the moveable platens associated with the half core moulds are in the retracted position. The recesses 31,32 on the underside of these moveable platens abut the shoulder 31 of the ring core 9. In addition, with the moveable platens 27,37 associated with the outer half moulds in the advanced position, the opposing means 6,16 defining a half orifice come together to from a riser to allow the egress of molten material. The outer half moulds also include recesses which come together to form a runner to allow the passage of molten metal into the mould.

Further, with the moveable platens associated with the half core moulds located in the retracted position, the moveable platens associated with the outer half moulds in the advanced position and the centre core 3 located between the half core moulds, each of the protuberances 33,34 abuts the outer surface of one of the half core moulds. The protuberances 33,34 serve to form the gudgeon pin holes in a cast piston.

With the moveable platens in these positions a casting cavity is defined. Molten material is introduced into the casting cavity to form a cast body 40. The cast body will include the solidified material from the runner 41 (Figure 5) and the riser 42. Once the cast body has achieved sufficient rigidity the centre core 3 is removed from between the half core moulds 8,18 to a position at which it does not interfere with any subsequent movement of the half core moulds (Figure 1).

Next, the moveable platens associated with the outer half moulds 5,15 are moved to the retracted position (Figure 2).

Finally, the moveable platens associated with the half core moulds are moved to the advanced position (Figure 3).

The cast body 40 may now be removed from the casting assembly (Figure 4).

It can be seen from Figure 5 that a number of cast bodies may be manufactured in a single cycle by using each of the pistons, piston rods and moveable platens to displace more than a single mould. In this Figure, on each side of the apparatus there can be seen a single moveable platen 27,37, each carrying four outer half moulds 5,15;43;44;45. Each platen 27,37 is driven by two pistons 10,46:11 ,47 by way of their associated piston rods 28,48,38,49. By the use of a similar construction applied in relation to the half core moulds, it will easily be understood that four cast bodies can be manufactured in a single processing cycle.

It will be seen that the casting axis, and the axis of movement of the clamping means are all coincident with the axis of symmetry. Further, it will be understood that for the cast body 40 of Figures 1 to 5 to be removed, the outer half moulds 5,15 need to be moved sufficiently apart to remove the protuberances 33,34 from the cast body 40, and also the half core moulds 8,18 need to be moved sufficiently close together to allow the cast body 40 to pass over the bulbous portions of the half core moulds. This requires the actuation of each and every mould clamping piston. The time interval before the apparatus can be used again following casting is largely related to the time delay in allowing all of the moulds to move sufficiently far to allow for the clearances noted above to remove the cast body 40 and then return the moulds to a position whereby the casting cavity is defined once again.

There is a need for a simpler casting apparatus that allows faster processing of castings. Turning to Figures 6 to 24, there are shown two similar embodiments of a casting apparatus according to the present invention; reference is particularly made to the apparatus of Figures 6 and 7 in describing the moulds and the formation of the casting cavity, and to the apparatus of Figures 8 to 24 in describing the means by which the moulds are adapted for movement. Like numerals are used to indicate like parts throughout.

The casting apparatus shown in Figures 6 and 7 allows for the production of eight cast bodies, four on either side of the casting apparatus. The casting apparatus shown in Figures 8 to 24 allows for the production of four cast bodies, two on either side of the casting apparatus. In each case, the apparatus for the production of each set of cast bodies mirrors the apparatus on the other side, and the means for producing each of the sets of cast bodies on each side of the casting apparatus run together in parallel. For this reason, the following description unless otherwise indicated will refer to the production of a single cast body on one side of the apparatus. As can clearly be seen this apparatus allows for the production of approximately twice the number of cast bodies by a casting apparatus occupying a similar amount of floor space to that of the illustrated prior art.

The apparatus is provided with a base 50. A vertically displaceable centre core 60 is adapted to extend through an opening (not shown) in the base. The centre core 60 is moveable between an advanced position and a retracted position.

The casting apparatus comprises first and second half core moulds 61 ,81 , the vertically displaceable centre core 60 being located between the first and second half core moulds, a ring core 90 located about the half core moulds 61 ,81 to limit the horizontal separation of the half core moulds, and first and second outer half moulds 64,84.

Each half core mould 61 ,81 is generally 'L' shaped and comprises a substantially horizontal member and a substantially vertical member, the substantially vertical member comprising a lower broader portion and an upper thinner portion. At an upper end of the upper thinner portion of each half core mould 61 ,81 there is an enlarged bulbous portion. The first half core mould 61 and the second half core mould 81 are configured such that in use the inner surfaces of the half core moulds are adapted to abut the centre core 60. The first half core mould 61 is secured by the substantially horizontal portion of the mould 61 to a first moveable platen 62. The first moveable platen 62 is connected to a first rod 51. The first rod 51 is provided with first, second and third stop members 52,53,54.

The second half core mould 81 is mounted for limited movement within a tray or recess 79 formed in a second moveable platen 80. The second moveable platen 80 is connected to a pair of rods 146,147. Each rod is provided at identical points along its length with two stop members 140,141. Supports 71 are provided through which each of the rods 146,147 is supported and guided for movement between each of the stop members 140,141. The pair of rods 146,147 are used to move the second moveable platen 80 between an advanced position and a retracted position. The second moveable platen 80 is provided with an opening through which that portion of the rod 51 between the third stop 54 and the first moveable platen 62 is adapted in use to pass.

The first and second moveable platens 62,80 are constrained for movement within a passage defined within a mounting assembly (not shown). A spacer element 72 is provided at an open end of the passage to retain the first and second moveable platens within the mounting assembly. The spacer element 72 is provided with an opening extending between front and rear faces of the spacer element 72. The spacer element is, in use, disposed between the second and third stops 53,54 on the rod 51.

The ring core 90 is located about the broader portion of the vertical members of the half core moulds, and rests upon the horizontal members of the half core moulds. The ring core 90 is general cylindrical comprising a generally upright wall, a radially outwardly extending flange 92 at a lower end of the wall and a circumferential protrusion or bead 91 about an upper end of the wall. The flange 92 of the ring core 90 forms a shoulder 93.

Each outer half mould 64,84 is generally half cylindrical in form and includes a recess 76,86 extending around the inner periphery of the mould and a generally cylindrical protrusion 77,87 extending radially inward from the outer half mould 64,84. The recesses 76,86 are of complementary shape to the circumferential bead 91 formed on the ring core 90. Means 65,85 defining a half orifice are located above each outer half mould 64,84.

The first outer half mould 64 is fixedly mounted to a fixed platen 82. The underside of the fixed platen 82 is provided with a recess 83. The shoulder 93 formed on the upper surface of the radial flange 92 of the ring core 90 is adapted in use to abut the internal surface of the recess 83.

The second outer half mould 84 is fixedly mounted on a third moveable platen 74. Movement means are provided comprising a piston cylinder 55 connected to the moveable platen 74 by a piston rod 148. It will be understood that any other convenient movement means may be used to move the platen 74 between an advanced position and a retracted position. A flange 73 depends from the third moveable platen 74. The flange 73 may be secured to or be integral with the third moveable platen 74. The flange 73 has first and second side faces. An opening extends between the first and second side faces of the flange 73 to allow the passage of the first rod 51 between the first and second stop members 52,53 on the first rod 51.

The underside of the third moveable platen 74 is provided with a recess 75 similar to that of the first outer half mould 64. The shoulder 93 formed on the upper surface of the radial flange 92 of the ring core 90 is adapted in use to abut the internal surface of the recess 75.

In order to create a casting cavity, all of the moulds are in their respective advanced positions. In this position, the third moveable platen 74 abuts the fixed platen 82 while both the third moveable platen 74 and the fixed platen 82 abut the ring core 90. In particular, the recesses 75, 85 on the underside of each of these platens abut the shoulder 93 of the flange 92 of the ring core 90. Also, the recesses 76, 86 of the outer half moulds 64,84 abut the peripheral bead 91 of the ring core 90. Each of the protuberances 77, 87 of the outer half moulds 64,84 abut one of the upper portions of the half core moulds 61, 81. Finally, the opposing means 25,85 defining a half orifice come together to form a riser to allow the egress of molten material from the casting cavity. At the same time, other half passages (not shown) in the outer half moulds come together to form a runner to allow the ingress of molten material to the casting cavity.

Molten material is directed into the casting cavity through the runner. Molten metal then fills the mould. The mould is known to be full when excess molten material has risen to the riser. The molten material may now be allowed to cool and to form a cast body 100. It can be seen that the cast body 100 is cast about an axis 56. Once the cast body 100 has achieved sufficient rigidity the centre core 60 is removed from between the half core moulds 61,81 to a position at which it does not interfere with any subsequent movement of the half core moulds (Figures 8 and 9).

The piston cylinder 55 is then actuated to withdraw the piston rod 148. This withdraws the moveable_platen 74 from an advanced position toward a retracted position (Figures 10 and 11). The second outer half mould 84 is in this way displaced away from the cast body 100 and the first outer half mould 64. The depending flange 73 is moved with the moveable platen along rod 51 from a position adjacent the second stop 53 on the rod 51 until a first face of the depending flange 73 comes into contact with the first stop 52 on the rod 51.

The cylinder continues to withdraw the moveable platen 74 and the associated depending flange 73. Accordingly, the rod 51 is now induced to move in the direction of the moveable platen 74. Since the first inner mould is fixedly attached by the platen to the other end of the rod, the first inner mould is also induced to move to separate the cast body 100 from the first outer half mould 64.

Subsequent movement of the piston rod moves the first inner half mould into contact with the second inner half mould. The second inner half mould then moves along the tray in which it rests, until it reaches an edge of the tray. The second inner half mould will tend to pivot about this point. This has the effect of loosening the second inner half mould from the casting.

Further movement of the piston rod moves the rod 51 from a position at which the second stop 53 is adjacent to a first face of spacer element 72 to a position at which the third stop 54 is adjacent to a second face of the spacer element 72 (Figures 12 and 13). Further movement of the rod 51 in this direction moves both the inner half moulds together and in this way prevents the two inner half moulds being brought too close to one another (Figures 14 and 15)

Withdrawal of the piston rod ceases when the first and second inner half moulds, together with the associated cast body 100, have been moved sufficiently far away from the first outer mould 64 to allow the cast body 100 to be freely removed from the casting assembly (Figures 16 and 17). At this point the first inner half moulds are in a position at which the second stops 141 on each of their associated rods 146,157 are adjacent to their respective supports 71.

The cast body 100 having been removed from the casting apparatus, the moulds are now returned to their initial positions to reform the casting cavity.

The piston cylinder is actuated to move the second outer half mould back towards the first outer half mould. The moveable platen 74 is moved towards the advanced position (Figures 18 and 19), together with the depending flange 73.

The flange passes over the rod 51 until the second face of the flange abuts the second stop member 53. (Figures 20 and 21). Further movement of the third moveable platen 74 and the associated flange 73 pushes the rod 51 and the associated first inner half core back towards the initial position (Figure 22). The first inner half core moves away from the second inner half core taking the ring core with it. The ring core, in a region oppositely disposed to that in contact with the first inner half core contacts the second inner half core to pull the second inner half core with it. It will be understood that in this way the inner half moulds are arranged at their maximum separation. At the same time the second stop 53 on the rod 51 contacts the spacer element 72 on the mounting assembly containing the moveable platens and the associated inner moulds and then moves the mounting assembly until (Figures 23 and 24) the inner moulds are returned to their initial positions (Figures 8 and 9). At this point the second inner half mould is in a position at which the first stops 140 on each of the associated rods 146,147 are adjacent to their respective supports 71.

Finally the vertically displaceable inner core 60 can be actuated to move between the first and second inner half core moulds to reform the casting cavity.

It can be seen that there exists both a casting axis 56 at a first location in the casting apparatus and an axis 57 in a plane parallel to the casting axis 56 displaced horizontally from the casting axis 56 at a second location within the casting apparatus (Figure 7).

In this way, the casting of an individual piston requires less floor space and accordingly for a similar unit area of floor space twice the numbers of cast bodies can be manufactured. This can be seen by reference to Figure 7. This Figure shows a view similar to that of Figure 5. It can be seen that a number of cast bodies may be manufactured in a single cycle displacing more than a single mould during a cycle. In Figure 7, on each side of the apparatus there can be seen a single first moveable platen 74 carrying four outer half moulds 84,143,144,145. Each first moveable platen 74 is driven by two piston cylinders 55,155 by way of their associated piston rods 56,149. It will easily be understood that eight cast bodies 100 can be manufactured in a single processing cycle compared to the four cast bodies possible in the illustrated prior art compared to the four cast bodies possible in the illustrated prior art.

In the present invention it is necessary only for the second outer half mould, connected to the third moveable platen, and the centre core mould to be driven by respective first and second movement means. This arrangement requires fewer movement means for each casting cycle than that required in the previously discussed casting apparatus. In addition space in the casting apparatus is required only for two such movement means.

Further, in the event of failure of either the first or second movement means on a first side of the casting apparatus during manufacture of the cast bodies, it is possible to continue manufacture, albeit at a reduced rate, using the other side of the casting apparatus until repairs are made to the movement means on the first side. Thus, even in the event of such a breakdown some production remains. This is an advantage over the illustrated prior art.

Claims

1. A casting apparatus comprising means defining a casting cavity at a first location in which a cast body is manufactured, the means defining the casting cavity comprising first and second half core moulds, a vertically displaceable centre core located between the first and second half core moulds, a ring core located about the half core moulds to limit the horizontal separation of the half core moulds, and first and second outer half moulds, characterised in that displacement means are provided to displace the cast body to a second location in the casting apparatus from the first location to allow removal of the cast body.

2. A casting apparatus according to claim 1, characterised in that the first outer half mould remains stationary throughout a casting cycle.

3. A casting apparatus according to claim 1 or claim 2, characterised in that movement of the half core moulds is determined by movement of the second outer half mould.

4. A casting apparatus according to any previous claim, characterised in that the second outer half mould is provided with displacement means to displace it towards and away from the first outer half mould.

5. A casting apparatus according to any previous claim, characterised in that the displacement means comprises hydraulically or pneumatically operated piston means.

6. A casting apparatus according to any previous claim, characterised in that the ring core includes a circumferential bead which is adapted for engagement with complementary recesses formed on the first and the second outer half moulds.

7. A casting apparatus according to any previous claim, characterised in that the first outer half mould is secured to a fixed platen and the second outer half mould is secured to a moveable platen.

8. A casting apparatus according to claim 7, characterised in that ring core includes a radially outwardly extending flange having a shoulder and each moveable platen is provided on a lower surface with a recess, the recesses and the shoulder being adapted to abut one another.

9. A casting apparatus substantially as described herein with reference to and as illustrated in Figures 6 and 7 of the accompanying drawings.

10. A casting apparatus substantially as described herein with reference to and as illustrated in Figures 8 to 24 of the accompanying drawings.

11. A method of manufacture of a cast body using a casting apparatus according to any previous claim comprising the steps of i) forming a casting cavity at a first location within the casting apparatus; ii) introducing molten material to the casting cavity to form a cast body; iii) allowing the cast body to cool; and iv) removing the cast body from the casting apparatus characterised in that after the cast body has achieved sufficient integrity it is moved to a second location within the casting apparatus at which location it can be removed from the casting apparatus.

12. A method of manufacture of a cast body substantially as described herein with reference to and as illustrated in Figures 6 and 7 of the accompanying drawings.

13. A method of manufacture of a cast body substantially as described herein with reference to and as illustrated in Figures 8 to 24 of the accompanying drawings.