CN115503196A

CN115503196A - Injection mold ejection mechanism and injection mold

Info

Publication number: CN115503196A
Application number: CN202211181817.4A
Authority: CN
Inventors: 梁良; 吴洲武; 李和先
Original assignee: Shenzhen Youruikang Mould Technology Co ltd
Current assignee: Shenzhen Youruikang Mould Technology Co ltd
Priority date: 2022-09-27
Filing date: 2022-09-27
Publication date: 2022-12-23
Anticipated expiration: 2042-09-27
Also published as: CN115503196B

Abstract

The invention discloses an injection mold ejection mechanism and an injection mold, and relates to the technical field of injection molds. The injection mold ejection mechanism comprises a supporting plate, wherein an ejection device is arranged on the surface of the supporting plate, the ejection device comprises a pushing device, a sliding plate is fixedly mounted at the output end of the pushing device, and a moving rod is slidably mounted on the surface of the sliding plate. This injection mold ejection mechanism, the inside gas of ejection frame can be extruded to the closing plate, when the closing plate can't be at the inside rebound of ejection frame, the closing plate can promote ejection frame rebound, ejection frame rebound can promote the inside piece rebound that moulds of bed die, the inside gas of ejection frame can be followed ejection frame both sides and discharged when ejection frame moves to the recess outside, can flow between piece and bed die through ejection frame spun gas realization, thereby can avoid moulding the adhesion on the inner wall of bed die.

Description

Injection mold ejection mechanism and injection mold

Technical Field

The invention relates to the technical field of injection molds, in particular to an injection mold ejection mechanism and an injection mold.

Background

Injection molding is a way of producing plastic articles by melting plastic to shape into a desired shape.

The utility model discloses a patent publication number is CN 216609914U's utility model relates to an injection mold ejection mechanism, comprises a workbench, workstation up end middle part fixedly connected with bed die, bed die up end plug-in connection has the last mould, ejecting device is installed to workstation up end one end, thrust unit is installed to the workstation up end other end, this utility model relates to an injection mold technical field, this injection mold ejection mechanism have solved the inconvenient problem that will mould the piece and take out and cause staff's hand scald easily when taking out of current injection mold. Above-mentioned utility model in through ejector pin rebound with moulding in the bed die ejecting, but have certain compliance when moulding the piece and not cooling the shaping completely, lead to moulding can laminate and can't break away from on the inner wall of bed die, and promote to mould a removal through ejector pin completely and also can lead to moulding a sunken damage.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides an injection mold ejection mechanism and an injection mold, and solves the problems in the background technology.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme: the utility model provides an injection mold ejection mechanism and injection mold, includes the backup pad, the surface of backup pad is provided with ejecting device, and ejecting device includes thrust unit, thrust unit's output fixed mounting has the slide, the surperficial slidable mounting of slide has the carriage release lever, the top of carriage release lever is slided and is cup jointed ejecting frame, the inner wall slidable mounting of ejecting frame has the closing plate, the top of carriage release lever is fixed with the bottom of closing plate, the inner wall of ejecting frame articulates there is the hang plate, the inner wall slidable mounting of ejecting frame has trapezoidal piece, the inside slidable mounting of trapezoidal piece has the elastic plate, one side that trapezoidal piece kept away from each other sets up to the inclined plane, and the through-hole has been seted up to ejecting frame's both sides, and pushing device can drive the slide rebound, and the slide can drive the carriage release lever rebound under the effect of the blockking of stopper and shell fragment when the slide rebound, can drive the closing plate to ejecting frame inside rebound when the carriage release lever rebound, can extrude the inside gas of ejecting frame when the closing plate rebound, and can drive the ejecting frame rebound outside of push out the frame, and can drive the outside of ejecting frame outside the spring and can drive the push out the spring when the outside of trapezoidal piece.

Preferably, the surface of the moving rod is fixedly provided with a limiting block, a torsion spring is arranged between the inclined plate and the ejection frame, the inclined plate is in contact with the sealing plate, and the sealing plate can be reset through the inclined plate.

Preferably, a first spring is arranged between the trapezoidal block and the ejection frame, and a second spring is arranged between the elastic plate and the trapezoidal block.

Preferably, the surface of backup pad is provided with the cooling and mends warm device, and the cooling and mend warm device includes cooling device, sealed frame and connecting pipe, cooling device fixed mounting is in the bottom of backup pad, sealed frame passes through connecting pipe and cooling device intercommunication, the inside fixed mounting of backup pad has electric putter, electric putter's output fixed mounting has the baffle, the baffle slides and runs through the connecting pipe, the bottom fixed mounting of baffle has the transfer line, the one end fixed mounting that the baffle was kept away from to the transfer line has the jam piece, the gas vent has been seted up to the bottom of sealed frame, opens cooling device, drives the baffle rebound through electric putter, and baffle rebound can drive the opening on the baffle and get into the inside of connecting pipe, makes the baffle can relieve the spacing to the connecting pipe, can drive the jam piece rebound through the transfer line during baffle rebound, and the jam piece rebound can seal up the gas vent to the bottom of sealed frame, makes the cooling gas that cooling device produced can get into the inside of sealed frame, can seal up the connecting pipe when the baffle rebound, and the jam piece can open the gas vent, discharges the inside cooling gas of sealed frame.

Preferably, the surface of sealed frame is provided with the heat sink, and the heat sink includes the arc frame, arc frame fixed mounting is on the surface of sealed frame, the top fixed mounting of arc frame has the heat sink, the top fixed mounting of jam piece has the diaphragm, the fixed surface of diaphragm installs the slider, can open the gas vent of sealed frame bottom when blockking up the piece downstream, can be with the inside cooling gas discharge of sealed frame, can drive diaphragm and slider downstream when blockking up the piece downstream, can remove the sealed of arc frame with sealed frame intercommunication department through the slider downstream, makes the inside steam of heat sink frame can get into the inside of sealed frame through the arc frame.

Preferably, the surface of baffle has seted up the opening, the jam piece contacts with the gas vent, the heat absorption frame passes through arc frame and the inside intercommunication of sealed frame, makes the baffle can relieve the sealing to the connecting pipe through the opening, makes the inside steam of heat absorption frame can get into the inside of sealed frame.

Preferably, the surface of slide is provided with the shake device, and the shake device includes the elastic block, elastic block fixed mounting is on the surface of slide, be provided with the shell fragment between slide and the stopper, the fixed surface of carriage release lever installs the arc piece, and ejection frame upwards promotes the resistance of moulding the piece and receiving and is greater than the elasticity of shell fragment, makes the slide can slide on the surface of carriage release lever, and the slide can drive the elastic block when moving the surface of carriage release lever and remove, can strike the arc piece when the elastic block removes, can drive the carriage release lever and ejection frame when the arc piece receives the striking and produce the vibration.

Preferably, the surface of the moving rod is fixedly provided with an arc-shaped elastic sheet, the surface of the arc-shaped elastic sheet is fixedly provided with a convex block, the bottom of the supporting plate is fixedly provided with a lantern ring, and the moving rod can drive the arc-shaped elastic sheet and the convex block to move when moving upwards.

An injection mold comprising: the lower die comprises an ejection mechanism, and the sealing frame is fixedly mounted at the bottom of the lower die.

(III) advantageous effects

The invention provides an injection mold ejection mechanism, which has the following beneficial effects:

(1) The push-out mechanism of the injection mold can drive the sliding plate and the moving rod to move upwards through the pushing device, the moving rod can push the sealing plate to move upwards in the push-out frame, the sealing plate can extrude gas in the push-out frame, when the sealing plate cannot move upwards in the push-out frame, the sealing plate can push the push-out frame to move upwards, the push-out frame can push the plastic part in the lower mold to move upwards, the gas in the push-out frame can be discharged from two sides of the push-out frame when the push-out frame moves towards the outer side of the groove, the gas sprayed out through the push-out frame can flow between the plastic part and the lower mold, and therefore the plastic part can be prevented from being adhered to the inner wall of the lower mold, when the push-out frame moves towards the outer side of the groove, the spring can push the trapezoidal block to move towards the outer side of the push-out frame, and the plastic part can be further prevented from being adhered to the inner part of the lower mold through the elastic plate and the trapezoidal block.

(2) This injection mold ejection mechanism, can drive the baffle through electric putter and block up the piece and remove, block up the piece and when sealed to the gas vent, the inside that the opening on the baffle can get into the connecting pipe can be relieved the baffle and to the sealing of connecting pipe, the cooling gas that makes cooling device produce can get into the inside of sealed frame, can cool off the bed die through the cooling frame, can seal the connecting pipe when the baffle moves down, it can open the gas vent to block up the piece, the inside cooling gas of sealed frame of discharge, the temperature of avoiding the bed die crosses lowly and leads to partial plastics to solidify fast and influence the mobile effect of plastics in the bed die.

(3) This injection mold ejection mechanism can adsorb the high temperature on bed die surface through the heat absorption frame and save, and when sealed frame blowout cooling gas, the inside high-temperature gas of heat absorption frame can get into the inside improvement sealed frame of sealed frame and bed die's temperature through the arc frame, further avoids the temperature of bed die to cross the effect of moulding plastics of influence excessively.

(4) This injection mold ejection mechanism, when the slide drives the slide bar rebound, when the resistance that ejecting frame rebound received is greater than the elasticity of shell fragment, the slide can make the elasticity piece can strike the arc piece at the surface movement of carriage release lever, make carriage release lever and bed die can produce the vibration, thereby can improve the effect of moulding the piece from the inside break away from of bed die, can drive arc shell fragment and lug rebound when the carriage release lever rebound, the lug rebound makes can strike the bed die, thereby can improve the frequency of bed die vibration.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic view of the overall multi-angle structure of the present invention;

FIG. 3 is a schematic view of a limiting block structure according to the present invention;

FIG. 4 is a schematic view of the cooling apparatus of the present invention;

FIG. 5 is a schematic view of the baffle structure of the present invention;

FIG. 6 is a schematic view of the internal structure of the sealing frame according to the present invention;

FIG. 7 is a schematic cross-sectional view of the lower mold of the present invention;

FIG. 8 is a schematic view of the internal structure of the ejector frame of the present invention;

FIG. 9 is a schematic cross-sectional view of a trapezoidal block of the present invention;

FIG. 10 is a schematic view of the heat absorbing frame of the present invention.

In the figure: 1. a support plate; 2. a lower die; 3. an upper die; 41. a pushing device; 42. a slide plate; 43. a travel bar; 44. ejecting the frame; 45. a sealing plate; 46. an inclined plate; 47. a trapezoidal block; 48. an elastic plate; 51. a cooling device; 52. a sealing frame; 53. a connecting pipe; 54. an electric push rod; 55. a baffle plate; 56. a transmission rod; 57. a plugging block; 58. a heat absorbing frame; 59. an arc frame; 510. a transverse plate; 511. a slider; 6. a limiting block; 71. an elastic block; 72. an arc-shaped block; 73. an arc-shaped elastic sheet; 74. a bump; 75. a collar.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

Referring to fig. 1-10, the present invention provides a technical solution: an injection mold ejection mechanism and an injection mold comprise a support plate 1, wherein an ejection device is arranged on the surface of the support plate 1, the ejection device comprises a pushing device 41, a sliding plate 42 is fixedly arranged at the output end of the pushing device 41, a moving rod 43 is slidably arranged on the surface of the sliding plate 42, an ejection frame 44 is slidably sleeved at the top of the moving rod 43, a sealing plate 45 is slidably arranged on the inner wall of the ejection frame 44, the top of the moving rod 43 is fixed with the bottom of the sealing plate 45, an inclined plate 46 is hinged to the inner wall of the ejection frame 44, a trapezoidal block 47 is slidably arranged on the inner wall of the ejection frame 44, an elastic plate 48 is slidably arranged inside the trapezoidal block 47, one side, away from each other, of the trapezoidal block 47 is arranged to be an inclined plane, through holes are formed in two sides of the ejection frame 44, the pushing device 41 can drive the sliding plate 42 to move upwards, when the sliding plate 42 moves upwards, the sliding plate 42 drives the moving rod 43 to move upwards under the blocking action of the limiting block 6 and the elastic sheet, when the moving rod 43 moves upwards, the sealing plate 45 is driven to move upwards towards the inside of the ejection frame 44, when the sealing plate 45 moves upwards, the gas inside the ejection frame 44 can be extruded, when the sealing plate 45 cannot continue to move upwards inside the ejection frame 44, the sealing plate 45 pushes the ejection frame 44 to move upwards, the gas inside the ejection frame 44 can be discharged from two sides of the ejection frame 44, when the ejection frame 44 moves to the outer side of the groove, the trapezoidal block 47 is driven to move towards the outer side of the ejection frame 44 under the action of the first spring, and the elastic plate 48 is driven to move towards the outer side of the trapezoidal block 47 under the action of the second spring.

The stopper 6 is fixedly mounted on the surface of the moving rod 43, a torsion spring is provided between the inclined plate 46 and the ejector frame 44, the inclined plate 46 is in contact with the sealing plate 45, and the sealing plate 45 can be returned by the inclined plate 46.

A first spring is arranged between the trapezoidal block 47 and the ejection frame 44, and a second spring is arranged between the elastic plate 48 and the trapezoidal block 47, so that the ejection frame 44 can be positioned in the groove, and two sides of the ejection frame 44 can be sealed through the groove.

The surface of the supporting plate 1 is provided with a cooling and temperature compensating device, the cooling and temperature compensating device comprises a cooling device 51, a sealing frame 52 and a connecting pipe 53, the cooling device 51 is fixedly arranged at the bottom of the supporting plate 1, the sealing frame 52 is communicated with the cooling device 51 through the connecting pipe 53, an electric push rod 54 is fixedly arranged inside the supporting plate 1, a baffle 55 is fixedly arranged at the output end of the electric push rod 54, the baffle 55 slides to penetrate through the connecting pipe 53, a transmission rod 56 is fixedly arranged at the bottom of the baffle 55, a blocking block 57 is fixedly arranged at one end, far away from the baffle 55, of the transmission rod 56, an exhaust port is formed in the bottom of the sealing frame 52, the cooling device 51 is opened, the baffle 55 is driven to move upwards through the electric push rod 54, the baffle 55 can drive an opening in the baffle 55 to enter the connecting pipe 53, the baffle 55 can release the limit of the connecting pipe 53, the blocking block 57 can be driven to move upwards through the transmission rod 56 when the baffle 55 moves upwards, the blocking block 57 can seal the exhaust port at the bottom of the sealing frame 52, and cooling gas generated by the cooling device 51 can enter the sealing frame 52.

The surface of sealed frame 52 is provided with the heat sink, the heat sink includes arc frame 59, arc frame 59 fixed mounting is on the surface of sealed frame 52, the top fixed mounting of arc frame 59 has heat absorption frame 58, the top fixed mounting who blocks up piece 57 has diaphragm 510, the fixed surface of diaphragm 510 installs slider 511, can open the gas vent of sealed frame 52 bottom when moving down through blocking up piece 57, can discharge the inside cooling gas of sealed frame 52, can drive diaphragm 510 and slider 511 to move down when blocking up piece 57 to move down, can remove the sealed of arc frame 59 and sealed frame 52 intercommunication department through slider 511 downward movement, make the inside hot gas of heat absorption frame 58 can get into the inside of sealed frame 52 through arc frame 59.

The surface of the baffle plate 55 is opened, the blocking block 57 contacts the exhaust port, the heat absorbing frame 58 communicates with the inside of the sealing frame 52 through the arc frame 59, the baffle plate 55 can be unsealed from the connecting pipe 53 through the opening, and hot air inside the heat absorbing frame 58 can enter the inside of the sealing frame 52.

The surface of slide 42 is provided with the shake device, the shake device includes elastic block 71, elastic block 71 fixed mounting is on the surface of slide 42, be provided with the shell fragment between slide 42 and the stopper 6, the fixed surface of carriage bar 43 installs arc piece 72, ejection frame 44 upwards promotes the resistance that moulds the piece and receive and is greater than the elasticity of shell fragment, make slide 42 can slide on the surface of carriage bar 43, slide 42 can drive elastic block 71 and remove when the surface movement of carriage bar 43, can strike arc piece 72 when elastic block 71 removes, can drive carriage bar 43 and ejection frame 44 when arc piece 72 receives the striking and produce the vibration.

The surface of the moving rod 43 is fixedly provided with an arc-shaped elastic sheet 73, the surface of the arc-shaped elastic sheet 73 is fixedly provided with a convex block 74, the bottom of the supporting plate 1 is fixedly provided with a lantern ring 75, and the moving rod 43 drives the arc-shaped elastic sheet 73 and the convex block 74 to move when moving upwards.

An injection mold comprising: go up mould 3 and bed die 2, bed die 2 fixed mounting is in the inside of backup pad 1, and the recess has been seted up to the inner wall bottom of bed die 2, and bed die 2 forms the die cavity with last mould 3 butt, and the die cavity is used for the injection moulding product, and bed die 2 includes foretell ejection mechanism, and heat absorption frame 58 passes through the heat pipe and contacts with bed die 2, and sealed frame 52 fixed mounting is in the bottom of bed die 2.

When the injection molding machine works (or is used), when injection molding is required, the injection molding machine is attached to a lower mold 2 through downward movement of an upper mold 3, high-temperature melting plastic is filled in the lower mold 2, a cooling device 51 is opened, a baffle 55 is driven to move upwards through an electric push rod 54, the baffle 55 moves upwards to drive an opening in the baffle 55 to enter the inside of a connecting pipe 53, the baffle 55 can be released from limiting the connecting pipe 53, the baffle 55 can drive a blocking block 57 to move upwards through a transmission rod 56 during upward movement, the blocking block 57 moves upwards to seal an exhaust port at the bottom of a sealing frame 52, cooling gas generated by the cooling device 51 can enter the inside of the sealing frame 52, the lower mold 2 can be cooled through the cooling gas in the sealing frame 52, and heat on the surface of the lower mold 2 can be adsorbed through a heat absorption pipe and the heat absorption frame 58.

Starting the pushing device 41, so that the pushing device 41 can drive the sliding plate 42 to move upwards, when the sliding plate 42 moves upwards, the sliding plate 42 can drive the moving rod 43 to move upwards under the blocking effect of the limiting block 6 and the elastic sheet, when the moving rod 43 moves upwards, the sealing plate 45 can be driven to move upwards towards the inside of the ejection frame 44, when the sealing plate 45 moves upwards, the gas inside the ejection frame 44 can be extruded, when the sealing plate 45 cannot continue to move upwards inside the ejection frame 44, the sealing plate 45 can drive the ejection frame 44 to move upwards, when the ejection frame 44 moves towards the outside of the groove, the sealing plate 45 can drive the trapezoidal block 47 to move towards the outside of the ejection frame 44 under the effect of the first spring, and when the ejection frame 44 moves towards the outside of the groove, the elastic plate 48 can be driven to move towards the outside of the trapezoidal block 47 under the effect of the second spring;

the resistance force borne by the plastic part pushed upwards by the ejection frame 44 is greater than the elastic force of the elastic sheet, so that the sliding plate 42 can slide on the surface of the moving rod 43, the sliding plate 42 can drive the elastic block 71 to move when moving towards the surface of the moving rod 43, the elastic block 71 can impact the arc-shaped block 72 when moving, the arc-shaped block 72 can drive the moving rod 43 and the ejection frame 44 to vibrate when being impacted, the vibration on the moving rod 43 can be transferred to the lower die 2, the moving rod 43 can drive the arc-shaped elastic sheet 73 and the lug 74 to move when moving upwards, the lug 74 can impact the lower die 2 when the arc-shaped elastic sheet 73 and the lug 74 move, and the lug 74 can vibrate through the lower die 2;

after the plastic part is separated from the lower die 2, the electric push rod 54 drives the baffle 55 to move downwards, the baffle 55 moves downwards to separate an opening on the baffle 55 from the connecting pipe 53, so that the baffle 55 can seal the connecting pipe 53, the baffle 55 can drive the blocking block 57 to move downwards through the transmission rod 56 when moving downwards, an exhaust port at the bottom of the sealing frame 52 can be opened when the blocking block 57 moves downwards, cooling gas in the sealing frame 52 can be exhausted, the transverse plate 510 and the sliding block 511 can be driven to move downwards when the blocking block 57 moves downwards, the sealing of the communication part of the arc-shaped frame 59 and the sealing frame 52 can be released when the sliding block 511 moves downwards, hot gas in the heat absorption frame 58 can enter the sealing frame 52 through the arc-shaped frame 59, and the temperatures of the sealing frame 52 and the lower die 2 can be improved.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides an injection mold ejection mechanism, includes backup pad (1), its characterized in that: the surface of backup pad (1) is provided with ejecting device, ejecting device includes thrust unit (41), the output fixed mounting of thrust unit (41) has slide (42), the surface slidable mounting of slide (42) has carriage release lever (43), the top slidable sleeve of carriage release lever (43) has ejecting frame (44), the inner wall slidable mounting of ejecting frame (44) has closing plate (45), the top of carriage release lever (43) is fixed with the bottom of closing plate (45), the inner wall of ejecting frame (44) articulates there is hang plate (46), the inner wall slidable mounting of ejecting frame (44) has trapezoidal piece (47), the inside slidable mounting of trapezoidal piece (47) has elastic plate (48).

2. An injection mold ejection mechanism as in claim 1, wherein: the surface of the moving rod (43) is fixedly provided with a limiting block (6), a torsion spring is arranged between the inclined plate (46) and the ejection frame (44), and the inclined plate (46) is in contact with the sealing plate (45).

3. An injection mold ejection mechanism as in claim 2, wherein: a first spring is arranged between the trapezoidal block (47) and the ejection frame (44), and a second spring is arranged between the elastic plate (48) and the trapezoidal block (47).

4. An injection mold ejection mechanism as in claim 3, wherein: the surface of backup pad (1) is provided with the cooling and mends warm device, and the cooling is mended warm device and is included cooling device (51), sealed frame (52) and connecting pipe (53), cooling device (51) fixed mounting is in the bottom of backup pad (1), sealed frame (52) are through connecting pipe (53) and cooling device (51) intercommunication, the inside fixed mounting of backup pad (1) has electric putter (54), the output fixed mounting of electric putter (54) has baffle (55), baffle (55) slide and run through connecting pipe (53), the bottom fixed mounting of baffle (55) has transfer line (56), the one end fixed mounting that baffle (55) were kept away from in transfer line (56) has jam piece (57), the gas vent has been seted up to the bottom of sealed frame (52).

5. An injection mold ejection mechanism as in claim 4, wherein: the surface of sealed frame (52) is provided with the heat sink, and the heat sink includes arc frame (59), arc frame (59) fixed mounting is on the surface of sealed frame (52), the top fixed mounting of arc frame (59) has heat sink frame (58), the top fixed mounting of jam block (57) has diaphragm (510), the fixed surface of diaphragm (510) installs slider (511).

6. The injection mold ejection mechanism and the injection mold of claim 5, wherein: the surface of the baffle plate (55) is provided with an opening, the blocking block (57) is contacted with the exhaust port, and the heat absorption frame (58) is communicated with the inside of the sealing frame (52) through an arc frame (59).

7. An injection mold ejection mechanism as in claim 6, wherein: the surface of slide (42) is provided with the shake device, and the shake device includes elastic block (71), elastic block (71) fixed mounting is on the surface of slide (42), be provided with the shell fragment between slide (42) and stopper (6), the fixed surface of carriage release lever (43) installs arc piece (72).

8. An injection mold ejection mechanism as in claim 7, wherein: the surface of the moving rod (43) is fixedly provided with an arc-shaped elastic sheet (73), the surface of the arc-shaped elastic sheet (73) is fixedly provided with a convex block (74), and the bottom of the supporting plate (1) is fixedly provided with a lantern ring (75).

9. An injection mold, comprising: the injection molding device comprises an upper die (3) and a lower die (2), wherein a groove is formed in the bottom of the inner wall of the lower die (2), the lower die (2) is abutted to the upper die (3) to form a cavity, the cavity is used for injection molding of a product, and the lower die (2) comprises the ejection mechanism as claimed in any one of claims 1 to 8.