Movable launder cover heating device

Abstract

The utility model discloses a movable launder cover heating device, relates to the technical field of aluminum alloy casting, and aims to solve the problem that a heated launder is heated unevenly, a lifting device is arranged at the top of a movable chassis so as to move along with the movable chassis, and the lifting device is provided with a lifting guide rod perpendicular to the movable chassis. The lifting device comprises a lifting support, the lifting support and the movable chassis are arranged in parallel, a launder cover is arranged on the lifting support, and the launder cover ascends and descends along the lifting guide rod along with the lifting support so that the launder cover can move to the position, needing to be heated, of the launder. A heating element is installed on the launder cover and connected with an electrical control device, the electrical control device is arranged on the top of the lifting guide rod and arranged on the side deviating from the lifting support, the heating element is controlled by the electrical control device to bake the launder, and it is guaranteed that the launder is heated evenly and the temperature is controllable in the baking process.

Description

Technical Field

[0001] The utility model relates to the technical field of aluminum alloy casting, and more specifically to a movable flow channel cover heating device. Background Art

[0002] The aluminum casting channel (referred to as the launder) is made of refractory materials. Before casting, the refractory launder needs to be baked for a certain period of time to remove the moisture attached to the refractory material and make the refractory material reach a certain temperature to reduce the temperature drop of the aluminum liquid, ensure the molding of the aluminum alloy casting and improve the internal metallurgical quality of the ingot. There are two types of aluminum casting launders: open and closed. The so-called closed type means that the launder needs to be fully sealed with a cover during casting, and inert gas is introduced into the sealed space to isolate the air and prevent the aluminum liquid from being oxidized.

[0003] Traditional aluminum alloy casting launders are usually baked with natural gas, but closed launders are inconvenient to bake with natural gas, and there are problems such as uneven baking, uncontrolled temperature, easy damage to the seal on the launder cover, and deformation of structural parts. Some current sealed launders have electric heating devices at the back end, but the heating capacity is often insufficient, so that the moisture in the launder cannot be completely dried. The liquid metal flows out of the static furnace and absorbs a lot of heat when it flows through the launder, so that the aluminum liquid flows to the end, causing a serious temperature drop, and it is difficult to ensure the ingot molding.

[0004] Therefore, how to solve the problem of uneven heating of the heated flow channel is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0005] In view of this, the purpose of the utility model is to provide a mobile launder cover heating device, which moves the launder cover to the position where the launder needs to be baked by moving the mobile chassis and lifting the lifting device, and controls the heating element to bake the launder through an electrical control device, thereby ensuring that the launder is heated evenly and the temperature is controllable during the baking process.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A mobile launder cover heating device, comprising:

[0008] Mobile chassis;

[0009] A lifting device is arranged on the top of the mobile chassis. The lifting device is provided with a lifting guide rod perpendicular to the mobile chassis. The lifting device is lifted and moved along the lifting guide rod. The lifting device includes a lifting bracket. The lifting bracket is lifted and moved along the lifting guide rod. The lifting bracket is arranged parallel to the mobile chassis.

[0010] The flow channel cover is arranged on the lifting bracket. The flow channel cover is lifted and moved along the lifting guide rod. A heating element is installed on the flow channel cover. The heating element is connected to the electrical control device. The electrical control device is arranged on the top of the lifting guide rod. The electrical control device is arranged on the side away from the lifting bracket.

[0011] Preferably, the mobile chassis comprises:

[0012] A bottom plate, wherein a wheel support is arranged at the bottom of the bottom plate, and four wheel supports are arranged evenly around the bottom plate;

[0013] There are four wheels, which are mounted on corresponding wheel supports, and the wheels are arranged at the bottom of the base plate through the wheel supports.

[0014] Preferably, the lifting device comprises:

[0015] The oil cylinder is arranged on the bottom plate along the height direction of the lifting guide rod, and a rotating handle is arranged on the oil cylinder, and the rotating handle is fixed to the oil cylinder;

[0016] A manual lifting rod is arranged on the bottom plate in parallel with the oil cylinder, and the manual lifting rod is used to raise the oil cylinder;

[0017] The sprocket device is arranged on the top of the oil cylinder.

[0018] Preferably, the sprocket device comprises:

[0019] The sprocket shaft is set in T shape, and the bottom end of the sprocket shaft is connected to the oil cylinder;

[0020] There are two chain gears, which are arranged at both ends of the sprocket shaft, and the chain gears are rotatably connected to the sprocket shaft;

[0021] The first chain is arranged in the circumferential direction of the chain gear, one end of the first chain is connected to the lifting bracket, and the other end of the first chain is connected to the crossbeam of the lifting guide rod.

[0022] Preferably, the lifting bracket comprises:

[0023] The first bracket is set in a U-shaped shape and is arranged in the groove of the lifting guide rod along the height direction of the lifting guide rod;

[0024] The second bracket is arranged perpendicular to the first bracket and is arranged parallel to the bottom plate.

[0025] Preferably, four second chains are symmetrically provided at the bottom of the second bracket, the second chains are fixed to the second bracket by screws and nuts, and the second chains are used to fix the flow channel cover.

[0026] Preferably, four pulleys are symmetrically provided on both sides of the first bracket, and the four pulleys are fixed to the first bracket through pulley fixing members, so that the first bracket moves along the groove.

[0027] Preferably, the flow channel cover comprises:

[0028] The cover body is provided with a U-shaped mounting hole, and the U-shaped mounting hole is provided through the cover body from the end surface of the cover body;

[0029] A stainless steel tube is arranged on the top of the cover body and is arranged along the length direction of the cover body;

[0030] There are two junction boxes, which are symmetrically arranged on the top of the cover body;

[0031] There are four connecting pieces, which are symmetrically arranged on the top of the cover body, and the connecting pieces are arranged one by one corresponding to the second chains;

[0032] There are four positioning pieces, which are symmetrically arranged on both sides of the cover body.

[0033] Preferably, a temperature measuring couple is provided on the top of the cover body, and the temperature measuring couple is connected to the electrical control device through a cable.

[0034] Preferably, the heating element is set to be U-shaped, the heating element is arranged in cooperation with the U-shaped mounting hole, and a fastener is provided at the end of the heating element to fix the position of the heating element and the cover body, and the heating element is a silicon carbon rod.

[0035] The mobile launder cover heating device provided by the utility model comprises a movable chassis, a lifting device, a launder cover, a heating element and an electrical control device; specifically, the lifting device is arranged on the top of the movable chassis so that the lifting device moves with the movable chassis, the lifting device is provided with a lifting guide rod perpendicular to the movable chassis so that the lifting device is lifted and moved along the lifting guide rod, the lifting device comprises a lifting bracket, the lifting bracket is arranged in parallel with the movable chassis, a launder cover is arranged on the lifting bracket, the launder cover is lifted and moved along the lifting guide rod with the lifting bracket so that the launder cover is moved to the position where the launder needs to be heated, a heating element is installed on the launder cover, the heating element is connected to the electrical control device, the electrical control device is arranged on the top of the lifting guide rod, the electrical control device is arranged on the side away from the lifting bracket, the heating element is controlled by the electrical control device to bake the launder, so as to ensure that the launder is heated evenly during baking and the temperature is controllable; the mobile launder cover heating device arranged in the above manner can reduce the temperature drop in the casting beginning process, facilitate the process control, and ensure that the temperature at the end of the launder meets the process requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0037] Figure 1 It is a left side view of the mobile launder cover heating device provided by the utility model;

[0038] Figure 2 A front view of the flow channel cover provided by the utility model;

[0039] Figure 3 It is a rear view of the mobile launder cover heating device provided by the utility model;

[0040] Figure 4 A front view of the mobile launder cover heating device provided by the utility model;

[0041] Figure 5 A top view of the flow channel cover provided by the utility model;

[0042] Figure 6 This is a cross-sectional view of the heating element provided by the utility model.

[0043] Figure 1-Figure 6 , the reference numerals include:

[0044] 1-mobile chassis, 11-bottom plate, 12-wheel support, 13-wheel;

[0045] 2-lifting device, 21-lifting guide rod, 22-lifting bracket, 221-first bracket, 222-second bracket, 23-oil cylinder, 24-manual lifting rod, 25-sprocket device, 251-sprocket shaft, 252-chain gear, 253-first chain;

[0046] 3-flow trough cover, 31-cover body, 32-stainless steel pipe, 33-junction box, 34-connector, 35-positioning piece;

[0047] 4- Heating element;

[0048] 5- Rotate the handle;

[0049] 6- Second chain;

[0050] 7-Pulley;

[0051] 8- Thermocouple. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0053] It should be noted that the directional words such as "upper" and "lower" described below are defined based on the drawings in the specification.

[0054] The core of the utility model is to provide a movable launder cover heating device, which moves the launder cover 3 to the position where the launder needs to be baked by moving the mobile chassis 1 and lifting the lifting device 2, and controls the heating element 4 to bake the launder through the electrical control device, ensuring that the launder is heated evenly and the temperature is controllable during the baking process.

[0055] Please refer to Figure 1 and Figure 2 A mobile launder cover heating device comprises a mobile chassis 1, a lifting device 2, a launder cover 3, a heating element 4 and an electrical control device.

[0056] Specifically, the lifting device 2 is arranged on the top of the mobile chassis 1 so that the lifting device 2 moves with the mobile chassis 1. The lifting device 2 is provided with a lifting guide rod 21 perpendicular to the mobile chassis 1 so that the lifting device 2 can be lifted and moved along the lifting guide rod 21. The lifting device 2 includes a lifting bracket 22, and the lifting bracket 22 is arranged parallel to the mobile chassis 1. A flow channel cover 3 is provided on the lifting bracket 22. The flow channel cover 3 is lifted and moved along the lifting guide rod 21 with the lifting bracket 22 so that the flow channel cover 3 moves to the position where the flow channel needs to be heated. A heating element 4 is installed on the flow channel cover 3, and the heating element 4 is connected to the electrical control device. The electrical control device is arranged on the top of the lifting guide rod 21, and the electrical control device is arranged on the side away from the lifting bracket 22. The heating element 4 is controlled by the electrical control device to bake the flow channel to ensure that the flow channel is heated evenly during baking and the temperature is controllable.

[0057] The movable launder cover heating device arranged in the above manner can reduce the temperature drop during the beginning of casting, facilitate process control, and ensure that the temperature at the end of the launder meets the process requirements.

[0058] In the above embodiment, the mobile chassis 1 includes a base plate 11, a wheel 13 support 12 and a wheel 13. Four wheel 13 supports 12 are provided at the bottom of the base plate 11. The four wheel 13 supports 12 are evenly arranged around the base plate 11. Four wheels 13 are provided. The four wheels 13 are installed on corresponding wheel 13 supports 12. The wheels 13 are arranged at the bottom of the base plate 11 through the wheel 13 supports 12.

[0059] It should be noted that a positioning hole is provided on the wheel 13 support 12, and a positioning screw is provided in the positioning hole. The wheel 13 support 12 is fixed to the bottom of the base plate 11 by the positioning screw. The wheel 13 support 12 is provided to connect the wheel 13 to the base plate 11, and the base plate 11 and the device on the base plate 11 are driven to move by the wheel 13.

[0060] Among them, the wheel 13 support 12 and the wheel 13 are set to four and distributed around the base plate 11 to make the entire device more stable when moving. However, in actual life, there is no limit to the number of wheel 13 support 12 and wheels 13, as long as the above-mentioned technical effect can be achieved.

[0061] Please refer to Figure 3 The lifting device 2 includes a cylinder 23, a manual lifting rod 24 and a sprocket device 25. The cylinder 23 is arranged on the bottom plate 11 along the height direction of the lifting guide rod 21. A rotating handle 5 is fixedly arranged on the cylinder 23. The manual lifting rod 24 is arranged on the bottom plate 11 parallel to the cylinder 23. The manual lifting rod 24 is used to lift the cylinder 23. The sprocket device 25 is arranged on the top of the cylinder 23.

[0062] It can be understood that the oil cylinder 23 is raised by the manual lifting rod 24, thereby driving the sprocket device 25 on the top of the oil cylinder 23 to move upward along the lifting guide rod 21, and the rotating handle 5 fixed on the oil cylinder 23 is rotated to move the oil cylinder 23 downward, thereby driving the sprocket device 25 on the top of the oil cylinder 23 to move downward along the lifting guide rod 21.

[0063] Please refer to Figure 4 The sprocket device 25 includes a sprocket shaft 251, a chain gear 252 and a first chain 253. The sprocket shaft 251 is set to be T-shaped. The bottom end of the sprocket shaft 251 is connected to the cylinder 23 so that the sprocket shaft 251 can be lifted and moved along with the cylinder 23. There are two chain gears 252, which are arranged at both ends of the sprocket shaft 251. The chain gears 252 are rotatably connected to the sprocket shaft 251. The first chain 253 is arranged in the circumferential direction of the chain gear 252. One end of the first chain 253 is connected to the lifting bracket 22, and the other end of the first chain 253 is connected to the crossbeam of the lifting guide rod 21.

[0064] It should be noted that the chain gear 252 rotates around the sprocket shaft 251 to drive the first chain 253 wound around the chain gear 252 to rotate, thereby driving the lifting bracket 22 to move up and down.

[0065] In the above embodiment, the lifting bracket 22 includes a first bracket 221 and a second bracket 222. The first bracket 221 is set in a U-shape. The first bracket 221 is set in the groove of the lifting guide rod 21 along the height direction of the lifting guide rod 21, and the second bracket 222 is set perpendicular to the first bracket 221 and parallel to the bottom plate 11.

[0066] It can be understood that the first bracket 221 is arranged in the groove of the lifting guide rod 21, so that the first bracket 221 can be lifted and moved along the groove of the lifting guide rod 21 to avoid the first bracket 221 from being deflected during the lifting process, and the second bracket 222 is connected to the first bracket 221, so that the second bracket 222 can be lifted and moved with the lifting of the first bracket 221 to ensure the synchronization of the lifting of the first bracket 221 and the second bracket 222.

[0067] On the basis of the above embodiment, four second chains 6 are symmetrically provided at the bottom of the second bracket 222 . The second chains 6 are fixed to the second bracket 222 by screws and nuts. The second chains 6 are used to fix the flow channel cover 3 .

[0068] It should be noted that the second bracket 222 is used to connect to the flow channel cover 3, and the second bracket 222 is connected to the flow channel cover 3 by setting screws, nuts and the second chain 6.

[0069] Among them, four second chains 6 are provided to make the connection between the second bracket 222 and the flow channel cover 3 more stable, but in actual life, there is no limit to the number of second chains 6 as long as the above-mentioned technical effect can be achieved.

[0070] In the above embodiment, four pulleys 7 are symmetrically disposed on both sides of the first bracket 221 , and the four pulleys 7 are fixed to the first bracket 221 through pulley 7 fixing members, so that the first bracket 221 moves along the groove.

[0071] It can be understood that, by providing the pulley 7, the first bracket 221 is moved in the groove, and the lifting and lowering movement of the first bracket 221 is completed, thereby driving the second bracket 222 to perform the lifting and lowering movement.

[0072] Among them, four pulleys 7 are provided to enable the first bracket 221 to move more smoothly in the groove, but in actual life, there is no limit to the number of pulleys 7 as long as the above-mentioned technical effect can be achieved.

[0073] Please refer to Figure 5The flow trough cover 3 includes a cover body 31, a stainless steel tube 32, a junction box 33, a connector 34 and a positioning member 35. The cover body 31 is provided with a U-shaped mounting hole, and the U-shaped mounting hole is set from the end surface of the cover body 31 through the cover body 31, so that the heating element 4 passes through the cover body 31, and the convection trough is heated more evenly. The stainless steel tube 32 is arranged at the top of the cover body 31 and is arranged along the length direction of the cover body 31 to fix the position of the cable on the cover body 31. There are two junction boxes 33, and the cables connected to the electrical control device are connected to the junction boxes 33. The two junction boxes 33 are symmetrically arranged at the top of the cover body 31 to balance the weight of the cover body 31. There are four connectors 34, and the four connectors 34 are symmetrically arranged at the top of the cover body 31. The connectors 34 and the second chains 6 are arranged one by one. There are four positioning members 35, and the four positioning members 35 are symmetrically arranged on both sides of the cover body 31 to fix the position of the cover body 31 and the flow trough.

[0074] It should be noted that, through the cooperation of the connecting piece 34 and the second chain 6, the cover body 31 is connected to the second bracket 222, so that the cover body 31 moves with the movement of the second bracket 222, and the cover body 31 is moved to the position where the flow channel needs to be heated by lifting and lowering the second bracket 222. The cover body 31 is fixed on the flow channel by the positioning piece 35, and a heating element 4 is set at the bottom of the cover body 31 to achieve heating of the flow channel.

[0075] Among them, there are four connecting members 34 and positioning members 35 to make the connection between the cover body 31 and the second bracket 222 and the flow channel more stable. The positioning members 35 are provided to prevent the cover body 31 from being offset from the flow channel during use, resulting in uneven heating.

[0076] In actual life, there is no limit to the number of connecting members 34 and positioning members 35 as long as the above technical effects can be achieved.

[0077] In the above case, a temperature measuring couple 8 is provided on the top of the cover body 31, and the temperature measuring couple 8 is connected to the electrical control device through a cable.

[0078] It can be understood that the thermocouple 8 can measure whether the temperature of the cover body 31 is consistent with the temperature at which the flow channel needs to be heated. The thermocouple 8 transmits the measurement result to the electrical control device in real time through the cable. The temperature control meter in the electrical control device displays the temperature of the cover body 31. If the heating temperature is not reached, the parameters of the power regulator in the electrical control device are adjusted to change the heating degree of the heating element 4 so that the temperature of the cover body 31 reaches the requirement; if the temperature of the cover body 31 reaches the requirement, the thermocouple 8 transmits the measurement result to the electrical control device in real time through the cable and displays it through the temperature control meter, and the heating element 4 is powered off.

[0079] Please refer to Figure 6 The heating element 4 is set to be U-shaped, the heating element 4 is arranged in cooperation with the U-shaped mounting hole, and a fastener is provided at the end of the heating element 4 to fix the position of the heating element 4 and the cover body 31. The heating element 4 is a silicon carbon rod.

[0080] It should be noted that the heating element 4 is configured to be U-shaped and passes through the U-shaped mounting hole at the bottom of the cover body 31 so that the end of the heating element 4 extends out of the upper end surface of the cover body 31, and the end of the heating element 4 is clamped with a fastener to prevent the heating element 4 from falling.

[0081] Among them, the heating element 4 is a silicon carbon rod, which has the characteristic of fast heating, can reduce the baking time, and can be raised to the baking temperature in a short time. In addition, the silicon carbon rod is not easy to deform at high temperature, so as to reduce the use and consumption of the heating element 4 and reduce the cost of auxiliary materials.

[0082] In summary, the mobile launder cover heating device provided by the utility model uses electric heating to bake the launder, which is cleaner and more environmentally friendly and reduces the use of non-renewable resources; an electrical control device is provided to make the baking process more convenient and controllable, and the heating element 4 is set to a silicon carbon rod to extend the service life of the heating element 4. The launder is fully heated by the heating element 4 to reduce the temperature drop during the beginning of casting, thereby facilitating process control, ensuring the one-time execution of the process, and improving product consistency.

[0083] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from other entities, but do not necessarily require or imply any actual relationship or order between these entities.

[0084] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0085] The above is a detailed introduction to a mobile launder cover heating device provided by the utility model. This article uses specific examples to illustrate the principle and implementation method of the utility model. The description of the above embodiment is only used to help understand the method and core idea of ​​the utility model. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the utility model, the utility model can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. A mobile launder cover heating device, characterized in that: include: Mobile chassis (1); A lifting device (2) is arranged on the top of the mobile chassis (1), the lifting device (2) is provided with a lifting guide rod (21) perpendicular to the mobile chassis (1), the lifting device (2) is lifted and moved along the lifting guide rod (21), the lifting device (2) comprises a lifting bracket (22), the lifting bracket (22) is lifted and moved along the lifting guide rod (21), and the lifting bracket (22) is arranged parallel to the mobile chassis (1); A flow channel cover (3) is arranged on the lifting bracket (22), the flow channel cover (3) is lifted and moved along the lifting guide rod (21), a heating element (4) is installed on the flow channel cover (3), the heating element (4) is connected to an electrical control device, the electrical control device is arranged on the top of the lifting guide rod (21), and the electrical control device is arranged on a side away from the lifting bracket (22); The mobile chassis (1) comprises: A bottom plate (11), wherein a wheel support (12) is provided at the bottom of the bottom plate (11), wherein four wheel supports (12) are provided, and the four wheel supports (12) are evenly arranged around the bottom plate (11); There are four wheels (13), the four wheels (13) are mounted on corresponding wheel supports (12), and the wheels (13) are arranged at the bottom of the base plate (11) through the wheel supports (12); The lifting device (2) comprises: An oil cylinder (23) is arranged on the bottom plate (11) along the height direction of the lifting guide rod (21); a rotating handle (5) is provided on the oil cylinder (23); and the rotating handle (5) is fixed to the oil cylinder (23); A manual lifting rod (24) is arranged on the bottom plate (11) in parallel with the oil cylinder (23), and the manual lifting rod (24) is used to lift the oil cylinder (23); A sprocket device (25) is arranged on the top of the oil cylinder (23); The sprocket device (25) comprises: The sprocket shaft (251) is set to be T-shaped, and the bottom end of the sprocket shaft (251) is connected to the oil cylinder (23); Two chain gears (252) are provided, and the two chain gears (252) are provided at two ends of the sprocket shaft (251), and the chain gears (252) are rotatably connected to the sprocket shaft (251); a first chain (253) arranged in the circumferential direction of the chain gear (252), one end of the first chain (253) being connected to the lifting bracket (22), and the other end of the first chain (253) being connected to the crossbeam of the lifting guide rod (21); The lifting bracket (22) comprises: A first bracket (221) is arranged in a U-shaped shape, and the first bracket (221) is arranged in a groove of the lifting guide rod (21) along the height direction of the lifting guide rod (21); A second bracket (222) is arranged perpendicular to the first bracket (221), and the second bracket (222) is arranged parallel to the bottom plate (11); Four second chains (6) are symmetrically arranged at the bottom of the second bracket (222), the second chains (6) being fixed to the second bracket (222) by means of screws and nuts, and the second chains (6) being used to fix the flow channel cover (3); The flow channel cover (3) comprises: A cover body (31), the cover body (31) being provided with a U-shaped mounting hole, the U-shaped mounting hole being provided from the end surface of the cover body (31) and penetrating the cover body (31), a temperature measuring thermocouple (8) being provided on the top of the cover body (31), the temperature measuring thermocouple (8) being connected to the electrical control device via a cable; A stainless steel tube (32) is arranged on the top of the cover body (31), and the stainless steel tube (32) is arranged along the length direction of the cover body (31); Two junction boxes (33) are provided, and the two junction boxes (33) are symmetrically arranged on the top of the cover body (31); There are four connecting members (34), the four connecting members (34) are symmetrically arranged on the top of the cover body (31), and the connecting members (34) and the second chains (6) are arranged in a one-to-one correspondence; There are four positioning members (35), and the four positioning members (35) are symmetrically arranged on both sides of the cover body (31); The heating element (4) is configured to be U-shaped, the heating element (4) being arranged in cooperation with the U-shaped mounting hole, a fastener being provided at the end of the heating element (4) to fix the position of the heating element (4) and the cover body (31), and the heating element (4) is a silicon carbon rod.

2. The mobile launder cover heating device according to claim 1, characterized in that: Four pulleys (7) are symmetrically arranged on both sides of the first bracket (221); the four pulleys (7) are fixed to the first bracket (221) via pulley fixing members, so that the first bracket (221) moves along the groove.

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