Switching type spray head assembly and 3D printer

Abstract

The utility model relates to the technical field of 3D printing, and particularly discloses a switching type spray head assembly and a 3D printer, the switching type spray head assembly comprises a first spray head, a second spray head and a switching device, the first spray head is connected with the switching device, and the second spray head is arranged on one side of the first spray head; the switching device comprises a moving part, a switching part and a driving part, wherein a sliding groove is formed in the moving part; when the moving part moves, the lifting block moves in the inclined direction of the inner side wall of the sliding groove so as to drive the lifting block to slide along the guiding part; and a mechanical movement switching mode is adopted, so that the control process is more convenient and faster, the energy loss is reduced, and the operation process is stable.

Description

Technical Field

[0001] The utility model relates to the technical field of 3D printing, and more specifically to a switchable nozzle assembly and a 3D printer. Background Art

[0002] 3D printing technology is often used to make models in the fields of mold manufacturing, industrial design, etc., and later gradually used for direct manufacturing of some products. At present, there are parts printed using this technology. This technology has a large number of applications in jewelry, footwear, industrial design, architecture, engineering and construction (AEC), automobiles, aerospace, dental and medical industries, education, geographic information systems, civil engineering, guns and other fields.

[0003] Existing 3D printers usually use a dual-nozzle structure, which can be switched back and forth during the printing process to meet the printing needs of different parts and different locations. However, in the existing switching device, it usually uses an electric drive to achieve the switch between the two nozzles, which increases energy consumption, and when errors occur in the nozzle switching, it is not possible to intuitively see whether the nozzle is switched in place. Utility Model Content

[0004] The utility model provides a switchable nozzle assembly and a 3D printer to solve the problems existing in the above-mentioned background technology.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0006] In the first aspect, the utility model provides a switchable nozzle assembly, comprising a first nozzle, a second nozzle and a switching device, wherein the first nozzle is connected to the switching device, and the second nozzle is arranged on a side of the first nozzle; the switching device comprises: a moving part, on which a sliding groove is arranged; a lifting block, on a first side of the lifting block, the first nozzle is arranged; a guide part, the guide part is fixedly arranged on one side of the moving part and movably passed through the lifting block, and the second side of the lifting block abuts against the inner wall of the sliding groove; when the moving part moves, the lifting block moves along the direction of the inner wall of the sliding groove to drive the lifting block to slide along the guide part.

[0007] In some embodiments of the present application, a plurality of pulleys are provided along the moving direction of the moving member, and the pulleys abut against the moving member.

[0008] In some embodiments of the present application, the switching device also includes a fixed part, and a limiting groove is provided on the movable part, and the limiting groove abuts against the fixed part; when the movable part moves, the limiting groove and the fixed part move relative to each other, and when the fixed part abuts against the side wall of the limiting groove, the fixed part limits the movable part.

[0009] In some embodiments of the present application, an elastic member is further included, wherein the elastic member abuts against the lifting block, and the lifting block slides along the guide member to enable the elastic member to generate a restoring force.

[0010] In some embodiments of the present application, a sliding portion is provided on the lifting block, and the lifting block is connected to the guide member via the sliding portion; or

[0011] In some embodiments of the present application, the first nozzle is a resin nozzle or a fiber nozzle, and the second nozzle is a resin nozzle or a fiber nozzle; or the first nozzle is a resin nozzle, and the second nozzle is a fiber nozzle.

[0012] In some embodiments of the present application, the resin spray head includes a first material guide pipe, and a cooling element, a heating element and a first nozzle are respectively arranged on the material guide pipe along the spraying direction of the resin spray head.

[0013] In some embodiments of the present application, the fiber nozzle includes a material guide assembly, a cutting assembly and a second nozzle; the material guide assembly includes a second material guide tube and a third material guide tube, there is a gap between the second material tube and the third material guide tube, one end of the third material guide tube is connected to the second nozzle, and the other end is opposite to the second material guide tube; the cutting assembly includes a driving assembly and a cutter, the driving assembly is transmission-connected to the cutter, the cutter is arranged on one side of the gap, and the driving assembly drives the cutter to cut the raw material passing through the gap.

[0014] In some embodiments of the present application, a resin feeding structure is further included, and the resin feeding structure is located on one side of the resin nozzle to feed the resin nozzle.

[0015] In a second aspect, a 3D printer is provided, comprising a 3D printer body and any one of the switchable nozzle assemblies described above.

[0016] Compared with the prior art, the utility model can realize the back and forth switching of the first nozzle by setting a moving part, a lifting block and a guide part, so that a height difference is formed between the first nozzle and the second nozzle. When the first nozzle is lowered, the first nozzle prints, and when the first nozzle is raised, the second nozzle starts printing. The electric energy drive in the traditional switching device is changed to a mechanical drive, and its working process is more stable and can reduce energy loss; by observing the relative position of the lifting block in the sliding groove, the relative position of the first nozzle can be observed more intuitively, and if an error occurs, it can be discovered in advance and stopped in time; the switching method using mechanical movement is also conducive to reducing the overall size of the nozzle, making the control process more convenient and fast, and the process stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the switchable nozzle assembly of the embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of the structure of the switching device according to an embodiment of the present application.

[0019] Figure 3 It is a schematic diagram of the structure of the moving part in the embodiment of the present application.

[0020] Figure 4 It is a schematic diagram of the structure of the resin nozzle in the embodiment of the present application.

[0021] Figure 5 It is a front view of the fiber nozzle in the embodiment of the present application.

[0022] Figure 6 It is a schematic diagram of the structure of the fiber nozzle in the embodiment of the present application.

[0023] Figure 7 It is a structural schematic diagram of the resin feeding structure in the embodiment of the present application.

[0024] Description of reference numerals:

[0025] 1- first nozzle;

[0026] 2- second nozzle;

[0027] 3-switching device; 310-moving member; 311-sliding slot; 312-limiting slot; 320-lifting block; 330-guide member; 340-sliding wheel; 350-fixing member; 360-elastic member;

[0028] 4-resin nozzle; 410-first material guide pipe; 420-cooling element; 430-heating element; 440-first nozzle;

[0029] 5-fiber nozzle; 510-material guide assembly; 520-cutting assembly; 521-cutter; 522-driving assembly; 533-second nozzle; 530-rotating shaft; 540-fiber fixing seat; 550-blade seat;

[0030] 6-resin feeding structure; 601-first roller; 602-second roller; 603-spring. DETAILED DESCRIPTION

[0031] Example 1

[0032] This embodiment provides a switchable nozzle assembly, please refer to Figure 1-3A switchable nozzle assembly includes a first nozzle 1, a second nozzle 2 and a switching device 3, wherein the first nozzle 1 is connected to the switching device 3, and the second nozzle 2 is arranged on one side of the first nozzle 1; the switching device 3 includes: a moving member 310, on which a sliding groove 311 is arranged; a lifting block 320, on which the first side of the lifting block 320 is arranged the first nozzle 1; a guide member 330, wherein the guide member 330 is fixedly arranged on one side of the moving member 310 and movably passes through the lifting block 320, and the second side of the lifting block 320 abuts against the inner side wall of the sliding groove 311; when the moving member 310 moves, the lifting block 320 moves along the inclined direction of the inner side wall of the sliding groove 311 to drive the lifting block 320 to slide along the guide member 330.

[0033] In some embodiments, for ease of explanation, this embodiment introduces a mounting plate, wherein a movable member 310 is horizontally arranged on the mounting plate, the movable member 310 is rod-shaped, and can move in a horizontal direction, a sliding groove 311 is arranged on the movable member 310, and the two side walls of the sliding groove 311 are inclined, and its bottom is horizontal, and the inclination angle of the two side walls is an obtuse angle, which is convenient for the subsequent movement of the lifting block 320; a first nozzle 1 is fixedly arranged on one side of the lifting block 320, and the other side of the lifting block 320 that is away from the first nozzle 1 is movably connected with the movable groove, and can move along the movable groove; the guide member 330 is vertically arranged relative to the horizontal direction of the movable member 310, and a plurality of guide members 330 can be selected, and a plurality of guide members 330 can make the lifting block 320 more stable and less likely to shake when moving, and the movable block is passed through the lifting block 320; the second nozzle 2 is fixedly arranged on one side of the first nozzle 1.

[0034] During use, the movable member 310 is slid in the horizontal direction. At this time, the sliding groove 311 starts to move, and one side of the lifting block 320 is gradually raised or lowered along its side wall driven by the sliding groove 311, so that the lifting block 320 rises or falls along the direction of the guide member 330, thereby realizing the height adjustment of the first nozzle 1 and forming a height difference between it and the second nozzle 2.

[0035] By setting the moving part 310, the lifting block 320 and the guide part 330, the first nozzle 1 can be switched back and forth to form a height difference between it and the second nozzle 2. When the first nozzle 1 is lowered, the first nozzle 1 is printed, and when the first nozzle 1 is raised, the second nozzle 2 starts to print. The electric energy drive in the traditional switching device 3 is changed to a mechanical drive, and its working process is more stable and can reduce energy loss; by observing the relative position of the lifting block 320 in the sliding groove 311, the relative position of the first nozzle 1 can be observed more intuitively, and if there is an error, it can be discovered in advance and stopped in time; the switching method using mechanical movement is also conducive to reducing the overall size of the nozzle, making the control process more convenient and stable.

[0036] In one embodiment, a plurality of sliding wheels 340 are provided along the moving direction of the moving member 310, and the sliding wheels 340 abut against the moving member 310. Preferably, the sliding wheels 340 are cam followers, and the sliding wheels 340 are used to reduce the friction force when the moving member 310 moves, and facilitate the sliding of the moving member 310 in the horizontal direction, so that the switching and adjustment process of the nozzle is more convenient and labor-saving, and the energy loss is reduced.

[0037] Preferably, the switching device 3 further comprises a fixing member 350, and a limiting groove 312 is provided on the moving member 310, and the limiting groove 312 abuts against the fixing member 350; when the moving member 310 moves, the limiting groove 312 and the fixing member 350 move relative to each other, and when the fixing member 350 abuts against the side wall of the limiting groove 312, the fixing member 350 fixes the moving member 310. The fixing member 350 is a fixed block, which is fixedly arranged above the moving member 310, and a limiting groove 312 is also provided on the moving member 310, and the side wall of the limiting groove 312 is at a ninety-degree or acute angle, and the bottom thereof is horizontal, so that when the fixing member 350 is close to the side wall, it cannot move, thereby limiting the entirety of the moving member 310, and preventing the moving member 310 from sliding out of the device and causing damage to the equipment.

[0038] In some embodiments, an elastic member 360 is further included, and the elastic member 360 abuts against the lifting block 320, and the lifting block 320 slides along the guide member 330 so that the elastic member 360 generates a reset force. Specifically, the elastic member 360 is a compression spring 603, and the compression spring 603 is arranged above the lifting block 320. At the same time, as the lifting block 320 passes through the guide member 330, when the lifting block 320 rises along the side wall of the sliding groove 311, it is stretched or compressed and deformed. When the lifting block 320 descends along the side wall of the sliding groove 311, at this time, the compression spring 603 will give the lifting block 320 a reset force to make the lifting block 320 descend. By adding the compression spring 603, it can make the switching device 3 more stable during use, and prevent the lifting block 320 from getting stuck during the descent process, etc., which affects the printing effect.

[0039] Furthermore, a sliding part is provided on the lifting block 320, and the lifting block 320 is connected to the guide member 330 through the sliding part. The sliding part is preferably an oil-free bushing, which can reduce the friction between the lifting block 320 and the guide member 330, making the sliding of the lifting block 320 along the guide member 330 easier and more labor-saving.

[0040] Example 2

[0041] This embodiment is similar to the embodiment 1, except that the first nozzle 1 is a resin nozzle 4 or a fiber nozzle 5, and the second nozzle 2 is a resin nozzle 4 or a fiber nozzle 5. The first nozzle 1 can be a resin nozzle 4, and the second nozzle 2 can be a fiber nozzle 5, or the first nozzle 1 is a fiber nozzle 5 and the second nozzle 2 is a resin nozzle 4, and the first nozzle and the second nozzle can also be fiber nozzles, which can be any combination of two, and this embodiment is not specifically limited. The nozzle designed by this method can realize the back and forth switching of the first nozzle 1, so that a height difference is formed between it and the second nozzle 2. When the first nozzle 1 is lowered, the first nozzle 1 is printed, and when the first nozzle 1 is raised, the second nozzle 2 starts to print. The electric energy drive in the traditional switching device 3 is changed to a mechanical drive, and its working process is more stable and can reduce energy loss; by observing the relative position of the lifting block 320 in the sliding groove 311, the relative position of the first nozzle 1 can be observed more intuitively, and the control process is more convenient and stable.

[0042] Example 3

[0043] This embodiment is similar to embodiment 2. Figure 4-7 As shown, further, the first nozzle 1 is a resin nozzle 4, and the second nozzle 2 is a fiber nozzle 5, wherein the resin nozzle 4 performs resin printing, and its function is the same as conventional FDM (fused deposition modeling technology) printing, heating and melting the filamentary thermoplastic material, extruding it through a fine nozzle, and depositing it layer by layer until the entire entity is shaped. In continuous carbon fiber printing, the main printing is performed on the outer surface of the part, including the upper and lower layers of the part, i.e., the side edge layers, and part of it is also used for internal filling. The fiber nozzle 5 performs continuous carbon fiber prepreg (carbon fiber composite filament) printing, by extruding the prepreg through the nozzle, and filling the continuous carbon fiber filament layer by layer into the interior of the part, thereby greatly improving the performance of the part, and realizing the combination of 3D printing of resin materials and continuous carbon fiber composite material laying, and both resin printing and fiber laying can provide an effective and stable nozzle device.

[0044] In some embodiments of the present application, the resin nozzle 4 includes a first material guide tube 410, and a cooling member 420, a heating member 430 and a first nozzle 440 are respectively arranged on the material guide tube along the spraying direction of the resin nozzle 4. The resin enters the resin nozzle 4 through the first material guide tube 410, and passes through the cooling member 420 and the heating member 430 in sequence, wherein the heating member 430 is a heating rod, and the cooling member 420 is a cooling block. The resin melts when passing through the area of ​​the heating member 430, and the melted resin is finally extruded through the first nozzle 440. The cooling member 420 dissipates the heat conducted from the heating block to avoid the temperature of the entire nozzle being too high, causing the resin to melt prematurely. The temperature difference inside the resin nozzle 4 is very important for printing. If the overall temperature is high and the resin is in a molten state inside the entire nozzle, it is easy to cause material blockage, and the high temperature area needs to be concentrated in the heating block area. Specifically, the first nozzle 440 is a key accessory for resin printing. Compared with conventional FDM printing nozzles, a stainless steel capillary is welded at the rear end of the fixed thread to guide the material. The added stainless steel tube guide can effectively guide the resin filament into the heating block area, and can avoid the leakage of the nozzle tail when printing with conventional FDM nozzles; an effective temperature difference can be formed between the cooling element 420 and the heating element 430, and it is not easy to form material blockage inside the nozzle. Preferably, the size of the stainless steel tube can be modified, and a section of Teflon tube can be installed inside to guide the material, so that the feeding is smoother.

[0045] In one embodiment, the fiber nozzle 5 includes a material guide assembly, a cutting assembly 520 and a second nozzle 533; the material guide assembly includes a second material guide tube and a third material guide tube, there is a gap between the second material guide tube and the third material guide tube, one end of the third material guide tube is connected to the second nozzle 533, and the other end is directly opposite to the second material guide tube; the cutting assembly 520 includes a driving assembly 522 and a cutter 521, the driving assembly 522 is connected to the cutter 521 by transmission, the cutter 521 is arranged on one side of the gap, and the driving assembly 522 drives the cutter 521 to cut the raw material passing through the gap. By arranging the cutting assembly 520 on the fiber nozzle 5, the requirement for continuous beating of broken wires of continuous carbon fiber composites can be met. Among them, the driving assembly 522 can be a driving motor, a gear rack, a driving cylinder, etc., which is not limited in this application, and only needs to drive the cutter 521 to cut the wire passing through the second material guide tube and the third material guide tube.

[0046] The fiber nozzle 5 in the above embodiment also includes a rotating shaft 530, a fiber fixing seat 540, a blade seat 550, and a driving assembly 522 which is a servo. The rotating shaft 530 is connected to the blade seat 550 and installed on the fiber fixing seat 540. The blade seat 550 is installed with a cutter 521, wherein the cutter 521 is a tungsten steel cutter 521. The blade seat 550 is connected to the driving end of the servo, and the blade seat 550 is driven by the servo to rotate, and the blade can pass through the gap between the second material guide pipe and the third material guide pipe. The prepreg composite material enters from the first material guide pipe 410, and the servo drives the rotation to drive the blade to cut the prepreg composite material, and then re-pass through the second nozzle 533 with the conveying of the wire material, so as to realize the function of continuous beating after the wire is broken. When shearing, the rotation angle of the servo needs to be adjusted, and the gap between the second material guide tube and the third material guide tube also needs to be adjusted to just pass through the blade. If the gap is too small, collision is likely to occur. If the gap is too large, the wire cut will be severely deformed, which is easy to block the wire or even the wire cannot be passed into the third material guide tube again, and thus cannot pass through the nozzle. A section of Teflon catheter can also be inserted into the second nozzle 533 to guide the material, which also reduces the influence of temperature on the prepreg composite material, is conducive to the smooth extrusion of the wire and is not easy to block the material. The front end of the second nozzle 533 is rounded, and because of the wear-resistant characteristics of carbon fiber, the nozzle needs to be processed with wear-resistant materials to avoid the influence of nozzle wear on the printing quality and reduce the probability of wire breakage during wire printing. The fiber nozzle 5 is driven by a servo to achieve shearing, and the structure is simple and stable. By adjusting the material guide tubes above and below the blade, the deformation of the wire shearing point can be effectively controlled to achieve stable wire feeding.

[0047] In some embodiments, a resin feeding structure 6 is further included, and the resin feeding structure 6 is located on one side of the resin nozzle 4 to feed the resin nozzle 4. Specifically, the resin feeding structure 6 includes a first roller 601, a second roller 602, a spring 603, and a roller driving assembly 522. The roller driving assembly 522 is a stepper motor, and the driving end of the stepper motor is connected to the first roller 601. The first roller 601 and the second roller 602 are arranged opposite to each other, and the first roller 601 and the second roller 602 clamp the resin. The stepper motor drives the first roller 601 so that the resin is squeezed between the first roller 601 and the second roller 602, wherein the spring 603 is arranged on one side of the first roller 601, and the wire clamping force is adjusted by squeezing the spring 603 by adjusting the screw.

[0048] Example 4

[0049] The present embodiment provides a 3D printer, including a printer body and a switchable nozzle assembly, wherein the switchable nozzle assembly is arranged on the printer body. In some embodiments, the printer body includes a moving module, wherein a driving end of the moving module is transmission-connected to the switchable nozzle assembly, and the moving module can drive the switchable nozzle assembly to move. When the moving module drives the switchable nozzle assembly to move to one side along the x-axis, the moving part can be supported to move the moving part, thereby driving the lifting block to move, and finally adjusting the height of the nozzle.

[0050] The 3D printer provided in this embodiment can form a height difference between the two nozzles when switching the nozzles. When the first nozzle 1 is lowered, the first nozzle 1 prints, and when the first nozzle 1 is raised, the second nozzle 2 starts printing. The electric energy drive in the traditional switching device 3 is changed to a mechanical drive, and its working process is more stable and can reduce energy loss. By observing the relative position of the lifting block 320 in the sliding groove 311, the relative position of the first nozzle 1 can be observed more intuitively. If an error occurs, it can be discovered in advance and stopped in time. The switching method using mechanical movement is also conducive to reducing the overall size of the nozzle, making the control process more convenient and stable.

[0051] The drawings are only for illustrative purposes and cannot be construed as limiting the present invention. To better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged, or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are only for illustrative purposes and cannot be construed as limiting the present invention.

[0052] The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for exemplary explanations and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0053] In the description of this application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, the specific relationship represented can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, they can understand the specific meanings of the above terms in this application according to specific circumstances.

[0054] Obviously, the above embodiments of the utility model are only examples for clearly explaining the utility model, and are not intended to limit the implementation methods of the utility model. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the utility model should be included in the protection scope of the claims of the utility model.

Claims

1. A switchable nozzle assembly, It is characterized in that It includes a first nozzle, a second nozzle and a switching device, wherein the first nozzle is connected to the switching device, and the second nozzle is arranged on one side of the first nozzle; The switching device comprises: A moving member, wherein a sliding groove is provided on the moving member; A lifting block, wherein a first nozzle is disposed on a first side of the lifting block; A guide member, the guide member is fixedly arranged on one side of the moving member and movably passes through the lifting block, and the second side of the lifting block abuts against the inner side wall of the sliding groove; When the moving member moves, the lifting block moves along the direction of the inner side wall of the sliding groove to drive the lifting block to slide along the guide member.

2. The switchable nozzle assembly according to claim 1, It is characterized in that A plurality of pulleys are arranged along the moving direction of the moving member, and the pulleys abut against the moving member.

3. The switchable nozzle assembly according to claim 1, It is characterized in that The switching device further comprises a fixing member, the moving member is provided with a limiting groove, and the limiting groove abuts against the fixing member; When the movable member moves, the limiting groove and the fixed member move relative to each other. When the fixed member abuts against the side wall of the limiting groove, the fixed member limits the movable member.

4. The switchable nozzle assembly according to claim 1, It is characterized in that It also includes an elastic member, which is in contact with the lifting block, and the lifting block slides along the guide member to enable the elastic member to generate a restoring force.

5. The switchable nozzle assembly according to claim 1, It is characterized in that The lifting block is provided with a sliding part, and the lifting block is connected with the guide member through the sliding part.

6. The switchable nozzle assembly according to claim 1, It is characterized in that The first nozzle is a resin nozzle or a fiber nozzle, and the second nozzle is a resin nozzle or a fiber nozzle; or the first nozzle is a resin nozzle, and the second nozzle is a fiber nozzle.

7. The switchable spray head assembly according to claim 6, It is characterized in that The resin spray head comprises a first material guide pipe, and a cooling element, a heating element and a first nozzle are respectively arranged on the material guide pipe along the spraying direction of the resin spray head.

8. The switchable nozzle assembly according to claim 6, It is characterized in that The fiber nozzle comprises a material guiding component, a cutting component and a second nozzle; The material guide assembly comprises a second material guide pipe and a third material guide pipe, a gap is formed between the second material guide pipe and the third material guide pipe, one end of the third material guide pipe is connected to the second nozzle, and the other end faces the second material guide pipe; The cutting assembly comprises a driving assembly and a cutter, wherein the driving assembly is in driving connection with the cutter, the cutter is arranged at one side of the gap, and the driving assembly drives the cutter to cut the raw material passing through the gap.

9. The switchable spray head assembly according to claim 6, It is characterized in that It also includes a resin feeding structure, which is located on one side of the resin nozzle and is used to feed the resin nozzle.

10. A 3D printer, It is characterized in that It comprises a 3D printer body and a switchable nozzle assembly as described in any one of claims 1 to 9.

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