IES80390B2 - A method and a mould for moulding a component - Google Patents

Abstract

A mould (2) for forming four identical spindles (1) in one shot with accurately located ratchet engaging gears (11) at respective opposite ends thereof comprises four mould cavities (19). The mould (2) is a four part mould comprising a first die plate (25) and a second die plate (29) and secondary dies (16). Cavities (49,50) in the first and second die plates (25,29), respectively, form the ratchet engaging gears (11), while respective halves of a cylindrical barrel (5) of the spindle (1) are formed by half portions (48) of the mould cavities (19), which are formed in the secondary dies (16). The first and second die plates (25) and (29) are located in first and second main dies (14,15), and as the dies (14,15) are moved towards each other, the secondary dies (16) are urged together for forming with the main dies (14,15) the mould cavities (19). By forming the ratchet engaging gears (11) in the first and second die plate (25,29) the gears (11) are located with relatively high angular accuracy relative to each other around a longitudinal axis (10). .

Description

LIMERICK, IRELAND.

(C) Copyright 1998, Government of Ireland.

S 8 0 3 9 0 S 9 70 8 1 8 i Appucen&· Ka~ A method and a mould for moulding a component The present invention relates to a method and a mould for moulding a component of the type which defines a longitudinally extending axis, and a pair of end formations at respective axially opposite ends thereof, and the invention also relates to a component formed by the method, typically, an elongated spindle of the type used in tensioning apparatus of a motor vehicle seatbelt, although needless to say, the invention is not limited to such a spindle.

In general, spindles for use in tensioning apparatus for motor vehicle seatbelts are of metal, typically, aluminium, and are cast. In order to function with the precision required, such spindles must be dimensionally particularly accurate. In general, such spindles define a central longitudinally extending axis, and are provided with ratchet engaging formations, which may be ratchet engaging gears or otherwise located on respective axially opposite ends of the spindle. It is essential that the ratchet engaging formations should be accurately located relative to each other angularly around the longitudinal axis of the spindle.

Otherwise, ratchets which engage the respective ratchet engaging formations will function incorrectly, and in the event of an accident, one or both of the ratchets may fail to engage the corresponding ratchet engaging gear, thereby leading to failure of the spindle locking for retaining the seatbelt. The need for dimensional accuracy of the ratchet engaging formations on the respective axially opposite ends of such spindles will be well known to those skilled in the art.

Typically, such spindles are cast in aluminium, and are moulded in a four part mould. Such four part moulds, in general, comprise a pair of main dies, which are carried on respective carrier plattens of a moulding press, and which are urged towards each other by the moulding press. A pair of secondary dies are slidably carried on one of the main dies, and as the main dies are urged towards each other by the moulding press, the main dies cooperate with the secondary dies for urging the secondary dies together for defining a mould cavity within which the spindle is moulded. Typically, such moulds for moulding seatbelt spindles comprise a number of cavities, typically, four cavities. In general, the cavities are located in the mould so that one side half of the spindle is formed in one of the main dies, and the other side half is formed in the other main die.

The ratchet engaging formations at the respective axially opposite ends of the spindle are formed in the secondary dies. In general, because of the construction of such four part moulds, the accuracy with which the secondary dies can be aligned with each other is limited, and in general, it is particularly difficult to ensure accurate angular location of the respective end formations of the spindle relative to each other around the longitudinal axis using such four part moulds in this way.

There is therefore a need for a method and a mould for moulding a spindle for use in tensioning apparatus of a vehicle seatbelt which overcomes these problems. There is also a need for a method and a mould for moulding any component having a longitudinally extending axis and end formations located at respective axially opposite ends of the component where accurate angular location of the end formations relative to each other around the longitudinal axis of the component is desirable. Additionally, there is a need for a spindle for a seatbelt tensioning apparatus with ratchet engaging end formations relatively accurately located relative to each other angularly around the longitudinal axis of the spindle, and there is also a need for a component which defines a longitudinally extending axis and which comprises end formations at respective axially opposite ends of the component which are relatively accurately located relative to each other angularly around the longitudinal axis.

The present invention is directed towards providing such a method, a mould, a component and a spindle.

According to the invention there is provided a method for moulding a component defining a longitudinal axis and having end formations at respective axially opposite ends thereof, the method comprising moulding the component in a four part mould having a first main die and a second main die, at least one of the main dies being moveable relative to the other main die in a direction towards and away from each other, and a pair of secondary dies, the secondary dies being slidably mounted on the first main die and being moveable relative to each other in a direction transversely of the direction of relative movement of the main dies, the secondary dies being cooperable with the main dies so that as the main dies are being moved towards each other the secondary dies are urged together for forming with each other and the main dies a mould cavity for moulding the component, the mould cavity defining the longitudinal axis of the component, wherein the component is moulded with the longitudinal axis thereof extending from one of the main dies to the other of the main dies, and the respective end formations are moulded one in each of the main dies for accurately locating the end formations on the component relative to each other angularly around the longitudinal axis.

Preferably, the longitudinal axis of the component defined by the mould cavity extends perpendicularly between the main dies, and advantageously, the longitudinal axis of the component defined by the mould cavity extends parallel to the direction of relative movement of the main dies.

In one embodiment of the invention the component is moulded in a moulding press, the mould being located in the moulding press with the longitudinal axis of the component defined by the mould cavity extending parallel to the line of action of the force in the moulding press for urging the main dies towards each other. In one aspect of the invention the main dies are mounted on respective corresponding main plattens in the moulding press.

In a further embodiment of the invention the component comprises a side formation on a side thereof, the side formation being located intermediate the end formations. Preferably, the side formation is formed by at least one of the secondary dies.

In one embodiment of the invention the component is of metal.

In another embodiment of the invention the component is of cast metal.

In another embodiment of the invention the metal of the component is aluminium.

Preferably, the material from which the component is to be moulded is delivered in fluent form into the mould cavity, and preferably, the material is delivered into the mould cavity in liquid form, and advantageously, the material is delivered into the mould cavity in molten form.

In one embodiment of the invention the component is an elongated spindle, and in another embodiment of the invention the spindle is for use in a tensioning apparatus for tensioning a motor vehicle seat belt, and in which case the end formations on the respective axially opposite ends of the component are ratchet engaging formations, typically, gears, for example, ratchet engaging gears.

Additionally, the invention provides a mould for moulding a component defining a longitudinal axis and having end formations at respective axially opposite ends thereof, the mould being a four part mould, and comprising a first main die and a second main die, at least one of the main dies being moveable relative to the other main die in a direction towards and away from each other, and a pair of secondary dies, the secondary dies being slidably mounted on the first main die and being moveable relative to each other in a direction transversely of the direction of relative movement of the main dies, the secondary dies being cooperable with the respective main dies so that as the main dies are being moved towards each other, the secondary dies are urged together for forming with each other and the respective main dies a mould cavity for moulding the component, the mould cavity defining the longitudinal axis of the component, wherein the mould cavity is located with the longitudinal axis of the component defined by the mould extending from one of the main dies to the other of the main dies, and the main dies define the respective end formations of the component so that the end formations are located accurately on the component relative to each other angularly around the longitudinal axis .

Preferably, a means for urging the secondary dies together as the main dies are being moved towards each other is provided. Advantageously, the means for urging the secondary dies together comprises a pair of spaced apart elongated guide bars extending from the second main die on respective opposite sides of the longitudinal axis of the component defined by the mould cavity, the guide bars diverging outwardly from each other from the second main die and being arranged for engaging corresponding receiving means in the respective secondary dies as the main dies are being moved towards each other for urging the secondary dies together. Advantageously, each receiving means comprises a guide bore for receiving one of the corresponding guide bars, the respective guide bores extending through the secondary dies from the first main die and converging towards each other so that on engagement with the guide bars as the main dies are being moved together, the guide bars and guide bores cooperate with each other for urging the secondary dies together.

In one embodiment of the invention a locating means is provided on one of the main dies for accurately locating the secondary dies relative to each other and relative to the main dies about the longitudinal axis of the component defined by the cavity. Preferably, the locating means is provided on the second main die and comprises at least one locating plug extending from the second main die for engaging corresponding locating recesses formed in the secondary dies. Ideally, the locating recesses in the secondary dies together define the periphery of the locating plug.

Advantageously, a pair of spaced apart locating plugs are provided for engaging corresponding locating recesses in the secondary dies, the secondary dies extending between the locating plugs.

In another embodiment of the invention a retaining means is provided for releasably retaining the secondary dies together. Preferably, the retaining means comprises a pair of side walls extending from the second main die for engaging corresponding side walls on the respective secondary dies as the secondary dies are being urged together. Advantageously, the side walls extending from the second main die diverge outwardly from each other from the second main die for engaging the secondary dies with a wedging action as the main dies are moved towards each other.

Advantageously, the side walls of the secondary dies converge towards each other from the first main die for cooperating with the side walls of the second main die with a wedging action.

In another embodiment of the invention at least one of the secondary dies defines a side formation for forming a corresponding side formation on the component intermediate the end formations on the ends thereof.

In one embodiment of the invention the mould cavity defines an elongated spindle. Preferably, the mould cavity defines an elongated spindle for use in tensioning apparatus of a motor vehicle seatbelt.

In one embodiment of the invention the end formations defined by the respective main dies are ratchet engaging formations. Typically, the end formations defined by the main dies are gears, for example, ratchet engaging gears.

Further the invention provides a moulding press comprising the mould according to the invention.

The invention also provides a component moulded using the method according to the invention, and further, the invention provides a component which is moulded using the mould according to the invention. The invention also provides a component which is moulded in the moulding press according to the invention.

In one embodiment of the invention the component is of metal, for example, cast metal, and in one aspect of the invention aluminium.

In another embodiment of the invention the component is an elongated spindle defining a longitudinally extending axis .

In another embodiment of the invention the spindle is -Λ. for use in a tensioning apparatus of a motor vehicle seatbelt.

Ideally, a pair of end formations are located at respective axially opposite ends of the spindle, the end formations being located accurately relative to each other angularly around the longitudinal axis, and each end formation may comprise a ratchet engaging formation, for example, a gear, typically, a ratchet engaging gear.

In another embodiment of the invention a side formation is formed on a side of the component intermediate the end formations .

Further the invention provides a spindle defining a longitudinally extending axis, and having a pair of end formations located at axially opposite ends thereof, the spindle being formed according to the invention.

In one embodiment of the invention the spindle is formed using the mould according to the invention.

The invention will be more clearly understood from the following description of a preferred embodiment thereof which is given by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a moulding press according to the invention comprising a mould also according to the invention for forming a component, namely, a spindle according to the invention using a method, also according to the invention, Fig. 2 is a perspective view of the spindle formed using the method according to the invention for use in tensioning apparatus of a motor vehicle seatbelt, Fig. 3 is another perspective view of the spindle of Fig. 2, Fig. 4 is a front elevational view of the spindle 15 of Fig. 2, Fig. 5 is an end view of the spindle of Fig. 2 from one end, Fig. 6 is an end view of the spindle of Fig. 2 from the other end, Fig. 7 is a perspective view of one part of the mould according to the invention, Fig. 8 is a perspective view of another part of the mould according to the invention, Fig. 9 is a front elevational view of the part of 5 the mould of Fig. 7, Fig. 10 is a front elevational view of the part of the mould of Fig. 8, Fig. 11 is a sectional side elevational view of the two parts of the mould of Figs. 7 and 8 on the lines XI-XI of Figs. 9 and 10, Fig. 12 is a sectional side elevational view of the two parts of the mould of Fig. 11 illustrated in a different position, Fig. 13 is a plan view of the two parts of the 15 mould of Figs. 7 and 8 on the line XIII-XIII of Fig. 11, and Fig. 14 is a sectional plan view of the parts of the mould of Fig. 13 illustrated in a different position on the line XIV-XIV of Fig. 12.

Referring to the drawings there is illustrated a spindle indicated generally by the reference numeral 1 which has been moulded by a moulding method according to the invention in a mould also according to the invention which is indicated generally by the reference numeral 2, and which is illustrated in Figs. 7 to 14, in a moulding press 3 illustrated in Fig. 1. In this embodiment of the invention the spindle 1 which is illustrated in Figs. 2 to 6 is of the type which is used in tensioning apparatus (not shown) of a motor vehicle seatbelt. Such spindles 1 will be well known to those skilled in the art. Before describing the mould 2 and method for moulding the spindle 1, the spindle 1 will first be briefly described.

The spindle 1 is of cast aluminium, and comprises a central cylindrical barrel 5 extending between circular end flanges 6. A slot 8 extends radially and axially through the barrel 5. A pair of stub shafts 9 extend axially from each end of the barrel 5. The stub shafts 9 and end flanges 6 are co-axial with the cylindrical barrel 5 and define a longitudinally extending central axis 10. Ratchet engaging end formations, in this case, ratchet engaging gears 11 are located at respective opposite ends of the spindle 1 on the end flanges 6 for engaging ratchets (not shown) in the tensioning mechanism (also not shown) of the motor vehicle seat belt. It is essential that the ratchet engaging gears 11 at the respective opposite ends should be accurately located angularly relative to each other around the central axis 10, and this is achieved by moulding the spindle 1 using the method according to the invention in the mould 2 which will now be described.

Referring to Figs. 7 to 14, the mould 2 is a four part mould comprising a first main die 14 and a second main die 15 and a pair of secondary dies 16 which in use are mounted in the moulding press 3, see Fig. 1. The secondary main dies 16 are slidably mounted on the first main die 14, and are arranged as will be described below so that as the main dies 14 and 15 are being moved towards each other in the direction of the arrow A, the secondary dies 16 are urged together in the direction of the arrows B, so that the secondary dies 16 define with each other and with the first and second main dies 14 and 15 four mould cavities 19 for moulding four of the spindles 1 in each shot. The first and second main dies 14 and 15 are mounted on a moveable carrier platten 20 and a stationary carrier platten 21, respectively, of the moulding press 3 so that as the platten 20 is moved in the direction of the arrow A towards the platten 21 in the moulding press 3 in an axial direction relative to the moulding press 3, namely, along an axis 22 defined by the moulding press 3 the first main die 14 is moved towards the second main die 15.

The first main die 14 comprises a first die plate 25 which is secured to a first die plate carrier 26, which in turn is secured to the moveable carrier platten 20 in the moulding press 3. A pair of secondary die carriers 27 are slidably carried on the first die plate carrier 26 through the first die plate 25, and slidably carry the secondary dies 16 across the first die plate 25. The second main die 15 comprises a second die plate 29 which is located in a recess 30 in a second die plate carrier 32. The second die plate 29 is located in a base 31 of the recess 30, and sits proud of the base 31 so that when the first and second die plate carriers 26 and 32 are urged towards each other into their final position with the mould 2 closed, the secondary dies 16 are tightly sandwiched between the first die plate 25 and the second die plate 29 so that the four mould cavities 19 are sealably closed. The second die plate carrier 32 is mounted on the stationary platten 21 of the moulding press 3.

An urging means for urging the secondary die carriers 27 and in turn the secondary dies 16 together as the main dies 14 and 15 are moving towards each other comprises three pairs of guide bars 34 which extend from the second die plate carrier 32 from the base 31 of the recess 30. The guide bars 34 extend from the base 31 on respective opposite sides of the mould cavities 19 and diverge outwardly from each other for engaging corresponding receiving means, namely, receiving bores 36 which extend through the secondary die carriers 27. The receiving bores 36 extend through the secondary die carriers 27 from the first die plate carrier 26 and converge towards each other from the first die plate 25 so that as the guide bars 34 engage the receiving bores 36 and the first main die 14 is moved further towards the second main die 15, the secondary die carriers 27 are in turn urged towards each other, thus, urging the secondary dies 16 together for forming the mould cavities 19.

A locating means for accurately locating the secondary dies 16 relative to the main dies 14 and 15 comprises a pair of locating plugs 38 which are formed on respective opposite top and bottom walls 39 of the recess 30 for engaging corresponding locating recesses 40, of which a half 41 of each recess 40 is formed on the respective secondary dies 16. The locating plugs 38 are of semi-circular cross-section, and the locating recesses 40 are likewise of corresponding semi-circular cross-section and each defines the cross-section of the corresponding locating plug 38 for locating the secondary dies 16 relative to each other and relative to the main dies 14 and 15 as the secondary dies 16 are urged together.

A retaining means for retaining the secondary dies 16 together during moulding of the spindles 1 in this embodiment of the invention is formed by a pair of outwardly diverging side walls 42 of the recess 30 which engage correspondingly converging side walls 43 of the secondary die carriers 27 with a wedging type action. Thus, as the main dies 14 and 15 are moved towards each other and the secondary dies 16 are urged together by the guide bars 34, when the secondary dies 16 are fully urged together, the action of the side walls 42 on the side walls 43 wedge the secondary dies 16 together for retaining the secondary dies 16 tightly together.

Four parallel guide rods 45 extend from the second die plate carrier 32 for engaging corresponding parallel guide bores 46 in the first die plate carrier 26 for guiding the first and second die plate carriers 25 and 32 as the die plate carriers 25 and 32 and in turn the main dies 14 and 15 are being urged towards and away from each other by the action of the plattens 20 and 21 of the moulding press 3.

Turning now to the mould cavities 19, each mould cavity19 defines one of the spindles 1. The secondary dies 16 each define a half portion 48 of the central part of each mould cavity 19. In other words, one of the secondary dies 16 defines the half portion 48 which forms one half of the cylindrical barrel 5 of the spindle 1, while the other secondary die 16 defines the other half portion 48 of the cavity 19 which forms the other half of the cylindrical barrel 5 of the spindle 1. Side formations which are to be formed on the barrel 5, for example, the slot 8 are formed by the respective half portions 48. The circular end flanges 6, the ratchet engaging gears 11 and the stub shafts 19 at the respective axially opposite ends of the spindle 1 are formed by cavities 49 and 50 in the first and second die plate 25 and 29, respectively. The detailed shapes formed in the portions 48 and the cavities 49 and 50 for forming the side and end formations of the spindle 1 are not illustrated. Accordingly, when the secondary dies 16 have been urged tightly together by the action of the first and second main dies 14 and 15 being moved towards each other, the secondary dies 16 are sandwiched between the first and second die plates 25 and 29, and thereby, the four mould cavities 19 are formed. The mould cavities 19 each define a longitudinally extending central axis 52, which in turn coincides with the longitudinal central axis 10 of the spindle 1. The central axes 52 of the mould cavities 19 extend perpendicularly from the first and second die plates 25 and 29, and extend generally parallel to the line of action of the force of the moulding press 3 which urges the plattens 20 and 21 and in turn the first and second main dies 14 and 15 towards each other in the direction of the arrow A.

Galleries (not shown) for carrying heating and cooling liquids through the first and second main dies 14 and 15 are provided. Such galleries for heating and/or cooling fluids will be well known to those skilled in the art. Delivery ducts for delivering molten aluminium into the cavities 19 are provided in the mould 2, although, these are not illustrated. However, the provision of such delivery ducts will be well known to those skilled in the art.

In use the mould 2 mounted in the moulding press 3, and the galleries for cooling fluid are connected to a suitable cooling fluid source. The platten 20 under the force of the moulding press 3 is moved in the direction of the arrow A towards the platten 21 for in turn moving the first and second main dies 14 and 15 towards each other. The action of the guide bars 34 on the receiving bores 36 urge the secondary dies 16 together in the direction of the arrows B for forming the four mould cavities 19. As the secondary dies 16 are coming close together, the locating recesses 40 engage the locating plugs 38 for accurately aligning the secondary dies 16 with each other and with the main dies 14 and 15 so that the half portions 48 of the main cavities 19 which are formed in the secondary dies 16 are accurately located and aligned relative to the end cavities 49 and 50 in the first die plate 25 and the second die plate 29, respectively. As the first die carrier plate 26 is urged into its final position relative to the second die plate carrier 32, the diverging side walls 42 of the recess 30 act on the converging side walls 43 of the secondary die carriers 27 for tightly securing the secondary dies 16 together. The molten aluminium is then delivered through the delivery duct (not shown) into the four mould cavities 19 and the mould 2 is retained securely closed until the aluminium has solidified. The platten 20 is then moved away from the platten 21, thereby moving the first and second dies 14 and 15 apart, and in turn, the secondary dies 16 apart. The moulded spindles 1 are then removed from the mould 2, and the mould 2 is ready for moulding the next shot of four spindles 1.

The advantages of the invention are many. The main and most important advantage of the invention is that the ratchet engaging gears 11 which are located at the axially opposite ends of the spindle are accurately located relative to each other about the central axis of the spindle 1. This is achieved by virtue of the fact that the spindles 1 are formed with their longitudinally extending central axis 10 extending perpendicularly from the first and second die plates 25 and 29. The first and second die plates 25 and 29 can be located significantly more accurately relative to each other than can the secondary dies 16.

Accordingly, by forming the ratchet engaging gears 11 in the first die plate 25 and the second die plate 29, respectively, the accuracy of the angular location of the ratchet engaging gears 11 relative to each other around the central axis 10 is significantly greater than in the case of spindles which are formed by conventional methods whereby the central axis of the spindle 10 extends between the secondary dies, in other words, where the ratchet engaging gears at the respective axially opposite ends of the spindle are formed in the secondary dies.

By using the method and the mould according to the invention it has been found that the end formations on the axially opposite ends of a component are formed with an angular accuracy of ± 2 minutes relative to each other. In other words, the angular accuracy around the centre line of a component which is achieved by using the method and the mould according to the invention is + 2 minutes end to end irrespective of the axial length of the component, within reason. The method and the mould is particularly suitable for components of axial length in the range of 20mm to 250mm.

While the method and the mould have been described for moulding a spindle for tensioning apparatus of a seatbelt, it will be appreciated that the method and mould may be used for moulding any type of spindle, or indeed, any other type of component where it is desired to form end formations on respective axially opposite ends of the component which are accurately formed relative to each other around a longitudinal axis of the component. Needless to say, it will be appreciated that the component may be moulded of any other mouldable material besides aluminium.

Claims (5)

1. A method for moulding a component defining a longitudinal axis and having end formations at respective axially opposite ends thereof, the method comprising moulding the component in a four part mould having a first main die and a second main die, at least one of the main dies being moveable relative to the other main die in a direction towards and away from each other, and a pair of secondary dies, the secondary dies being slidably mounted on the first main die and being moveable relative to each other in a direction transversely of the direction of relative movement of the main dies, the secondary dies being cooperable with the main dies so that as the main dies are being moved towards each other the secondary dies are urged together for forming with each other and the main dies a mould cavity for moulding the component, the mould cavity defining the longitudinal axis of the component, wherein the component is moulded with the longitudinal axis thereof extending from one of the main dies to the other of the main dies, and the respective end formations are moulded one in each of the main dies for accurately locating the end formations on the component relative to each other angularly around the longitudinal axis.

2. A method as claimed in Claim 1 in which the component is moulded in a moulding press, the mould being located in the moulding press with the longitudinal axis of the component defined by the mould cavity extending parallel to the line of action of the 5 force in the moulding press for urging the main dies towards each other.

3. A method for moulding a component defining a longitudinal axis and having end formations at respective axially opposite ends thereof, the method 10 being substantially as described herein with reference to and as illustrated in the accompanying drawings.

4. A mould for moulding a component defining a longitudinal axis and having end formations at respective axially opposite ends thereof, the mould 15 being a four part mould, and comprising a first main die and a second main die, at least one of the main dies being moveable relative to the other main die in a direction towards and away from each other, and a pair of secondary dies, the secondary dies being slidably 20 mounted on the first main die and being moveable relative to each other in a direction transversely of the direction of relative movement of the main dies, the secondary dies being cooperable with the respective main dies so that as the main dies are being moved 25 towards each other, the secondary dies are urged together for forming with each other and the respective main dies a mould cavity for moulding the component, the mould cavity defining the longitudinal axis of the component, wherein the mould cavity is located with the 5 longitudinal axis of the component defined by the mould extending from one of the main dies to the other of the main dies, and the main dies define the respective end formations of the component so that the end formations are located accurately on the component relative to 10 each other angularly around the longitudinal axis.

5. A component moulded using the method according to any of Claims 1 to 3, and the mould according to Claim