Cold extrusion forming of spiral extrusion machine

Machinery and Equipment Vacuum Extrusion Molding Machine Spiral Cold-drawing Forming Cai Zuguang (Xiangtan Xintan Ceramics Machinery Co., Ltd., Hunan 411102) The drawing method for unrolling materials; detailed description of the spiral manufacturing method for cold-drawn spiral surfaces. It has the advantages of simple production process, low cost and good quality of spiral surface forming. It is the best way for wall and floor tile manufacturers to manufacture spirals and facilitate maintenance of vacuum extrusion molding machines.

Vacuum extrusion molding machine is the key equipment for plastic extrusion molding of special-shaped products such as honeycomb ceramics, ceramic rods, ceramic plungers, and wall tiles. The spiral has the effects of crushing, stirring, kneading, mixing evenly and extruding tightly on the ceramic slurry, and promotes the ceramic slurry to become a green body with a certain shape and size. It can be seen that the spiral is the key component of the vacuum extrusion molding machine, but it is prone to wear. In order to ensure the normal operation of the vacuum extrusion molding machine, it is necessary to replace the worn spiral in time. Because the traditional manufacturing method of the spiral is formed by casting and then mechanical cutting, the production cycle is long, and it is very difficult for the manufacturer of wall and floor tiles with poor mechanical manufacturing capability to process and manufacture the spiral. Herein, the author introduces a spiral manufacturing method for manufacturing a simple and cold-drawn spiral surface.

2 Helix unfolding and blanking As shown in the figure, the spiral of the vacuum extrusion molding machine can be roughly divided into equal-width cylinder spirals (such as mud spirals and mud spirals), constant-width cone spirals (such as cone spirals), and unequal widths. Cylindrical helix (such as auger) and unequal conic helix (such as cone helix) in four structural forms. When using a cold drawing to form a spiral surface, the helical surface must first be unfolded into a flat pattern for easy feeding. In practical production, the helical surface in one lead can usually be expanded into a notched ring, and the error is small, which will not affect the working performance.

2.1 isotropic cylindrical spiral vacuum extrusion machine spiral structure. 1.1 Dimension calculation According to the formation principle of the spiral surface, the actual length of the internal and external spiral lines in a lead diagram is shown as follows. By solving the right angle triangle: 1-=V(!Q2+H12=V, and according to the ring For nature, find the inner and outer radii Ri and Rd of the unfolding ring of a constant-height cylindrical spiral surface within a lead to satisfy the following relationship: Rh then the notch angle of the unrolling ring is “=36!-i8K= The radius of the outer edge is considered everywhere after the machining allowance C is connected sleekly, that is, a drawing diagram of the cylindrical spiral surface of a lead and the like is drawn by cold drawing (shaded part shown in a).

2.2 Constant-width conic spiral 2.2.1 Calculation of the size By substituting the large-end hub size of a constant-width conical helix into the above-mentioned formula for the equal-width cylinder helix, one can derive the radius of the inner circle of a lead-out imaginary equal-helix cylinder. The central angle of the ring notch" and the length of the inner chord of the unfolding ring-notch portion A = 2R * Sinf. For ease of solution, the constant width circle 2.2.2 can be used as the material to be expanded. 1) Take any point O as the center to R1 The radius is drawn on the circle, and the length of the notch is calculated by taking the length of the chord A and the length of each chord and connecting it to the circle center O. Then, measure the radius of the spiral inwards according to the direction of the spiral ( N-1)E, where: n=1,2,3,...,m Obtain each point. Connect each point sleekly to obtain the lead-out line of the inner helix of a conical helix with a lead; then use an equal-width cone. Each point of the inner line of the helix of the helix is ​​obtained by measuring the width B of the helicoid outwardly in the radial direction, and by smoothly connecting the points, an approximate development view of a helix of the same width of the lead is obtained.

(2) The radius of the outer edge of the above-mentioned unfolded drawing is considered to be rounded to connect the points in consideration of the machining allowance C, that is, an unrolled blank drawing of a lead-cone-width conical helix surface is formed by cold drawing (the hatched portion shown in b).

2.3 Unequal width cylindrical spiral 2.3.1 Dimensional calculation Substituting the size of the large end of the unequal width cylindrical screw hub into the above formula for the constant width cylindrical helix to obtain the inside of the lead line of the hypothetical equal width cylindrical spiral surface of a lead. The radius RnR of the outer ring, the central angle of the ring notch" and the inner chord length of the unfolded ring notch (= 2+ * Sinf. For ease of solution, the inner spiral of the unequal cylinder spiral may be divided into m equal parts ( Taking into account the convenience of mapping and the error is small, usually m*12) is chosen, then the inner helical line of a lead unequal width cylindrical spiral is unrolled and each aliquot length is A*2+*Sin, while the unequal width cylinder The difference between the size of the hub and the radius of the hub is 24, then the difference between the size and the hub radius of the unequal cylindrical helix.

2.3.2 The drawing of the unrolled material is centered on any point 0, and the concentric circles are drawn on the radius of the mass, and the outer circumference is the unfolding line of the outer spiral of the unequal-width cylindrical helix.

On the inner circumference, take the spiral length of the spiral and take the chord length A and each chord length A of the notch and connect it to the center 0; then, measure the direction of the spiral from each point in the radial direction (m- 1)E, where n*1,2,3...,m obtains points. By connecting each point sleekly, the unfolding line of the inner spiral of the cylindrical spiral with different lead widths is obtained; the unfolding line of the inner and outer spirals is obtained. The enclosed pattern is an approximate unfolded view of a helicoidal plane with a different lead width.

After the machining allowance C is taken into consideration in the radial direction of the outer edge of the approximately developed diagram, the points are rounded and connected, that is, an unfolded blank drawing diagram of a cylindrical spiral surface of unequal lead width is formed by cold drawing (for example, a shaded portion is shown).

2.4 Unequal-width conic spirals 2.4.1 Dimensional calculations Substituting the large-end size of unequal-width conical helix planes into the above-mentioned formula for a constant-width cylinder helix, one can find the interior of the unfolding ring of a constant-width cylindrical helix of a lead. The radius of the outer circle is +, +, and the central angle of the ring gap is! And to expand the outer chord length of the annular notch portion A*2+sinf. In order to facilitate the solution, the outer spiral of the unequal-width conic helix can be divided into m equal parts (since the ease of drawing and the error are small, etc., usually m is selected. *12), then a lead with unequal width of the conical helix surface of the external helix unfolds each chord length A*2-R236-! , At the same time, the difference between the widths of the ends of the unequal width of the conical helix (B-=), then the difference between the widths of the ends of the unequal width of the conical helix, E*==1. 2.4.2 Drawing of the material Take any point 0 as the center and draw a concentric circle with +, +2 as the radius. The inner circle is the unfolding line of the inner spiral of the unequal-width cone spiral.

On the other circumference, the length of the outer chord A and the length of each chord A of the notch portion are taken along the spiral of the spiral and connected to the center 0; the direction of the helix is ​​taken inwards from the radial direction at each point (n- 1)E, where n*1,2,3...,m obtains each point. The sleek connection of the points results in the unfolding line of the outer spiral of the lead with unequal conic helix; The resulting image is an approximate unfolded view of a conical helicoid with a different lead width.

After considering the machining allowance C at the radius of the outer edge of the above-mentioned expansion diagram, the points are rounded and connected. That is, an unfolded cutting chart of a conical spiral surface with unequal lead width is drawn by cold drawing (shaded portion shown by d).

3 Spiral cold drawing 3.3.1 Pretreatment of the unrolled material After unwinding the material with the oxygen block flame cutting material, the internal surface of the ring is polished with an electric angle grinder and the vise On the upper end of the ring-shaped unwinding material gap, the ends of the annular unwinding material are forced to be flush (as shown), and the annular unrolled material is axially displaced by a certain distance according to the spiral direction (as shown, for the purpose of facilitating cold-drawn forming of the spiral surface and Easy installation, usually 40 to 50mm staggered.) Then cold-formed process joints are welded on the outer sides of the ring-shaped unrolled material (process holes with a diameter of 20mm are machined on the two process joints, as shown) , Convenient for cold drawn forming spiral face fashion clips.

3.2 Preparation of cold-drawn mandrels The helical mandrels are machined in a manner similar to the structure of the screw hubs. The cylindrical mandrels shown in a are suitable for constant-width cylindrical spirals Spiral cold-drawing forming mandrel with wide conical helix, conical mandrel as shown in b for constant-width conic helix and unequal width (a) Cylindrical type (b) Cone-type cold drawing forming mandrel The helical mandrel for cold drawing of the spiral helix is ​​shown in the drawing. The ad and H in the figure are the major diameter, the minor diameter and the spiral lead of the screw hub respectively.

3.3 Cold-drawing forming As shown in the schematic drawing of cold drawn forming spiral surface, the cold-drawn forming mandrel is firmly fixed on the workbench through the bottom cylindrical positioning surface, hexagon bolts, flat washers and spring washers, etc., and then passed through cold drawing. Forming mandrel positioning Position the pre-treated helicoid unrolled material on the workbench and pass the welded joints, pin bearings, pins, cotter pins, hex bolts, hex nuts, flat washers and spring washers It is firmly fixed on the workbench; the other end is also fixed on the movable beam by welding joints, pin bearings, pin shafts, split pins, hexagon bolts, hexagon nuts, flat washers and spring washers; The vertical hydraulic jack will generate a predetermined displacement, and force the movable beam to move upwards gradually through a thrust plate, a thrust rod, etc., and gradually expand the spiral surface expansion material. By controlling the upward movement position of the movable beam, a lead spiral can be obtained. Cold drawing of the surface.

9 Worktable 10 Thrust plate 11 Vertical hydraulic jack 12 Schematic drawing of cold drawn forming helicoidal structure It is worth noting that: When the helical surface is cold drawn and unfolded, the force should be slow and uniform, and the spiral surface should be tapped continuously with a boring head. The outer edge of the material is unrolled, forcing the entire spiral surface to deform evenly until the inner surface of the spiral surface material is in close contact with the surface of the cold drawing forming mandrel. In order to reduce cold drawing resistance and improve the forming accuracy of the spiral surface, on the one hand, lithium sodium base grease or other lubricant should be applied on the working surface of the cold drawing forming mandrel and the inner surface of the spiral surface developing material; on the other hand, it should be ensured. The relative positions of the pin support on the movable beam and the pin support fixed on the work table ensure that the outer surfaces of both ends of the spiral surface are in a straight line and are parallel to the spiral axis. By changing the length of the thrust rod, the size of the cold drawn forming mandrel, and the vertical size of the hydraulic jack, a large variety of spiral surfaces can be obtained.

4Helicoid welding and processing remove the spiral surface formed by cold drawing, use the oxygen block flame cutting welding process joint to prepare for the next use; use the point angle grinder to polish the joint with the process joint. The spiral surface is processed according to the spiral structure. The internal hole and the two ends of the screw hub must be machined. Then the spiral surface is firmly welded to the screw hub by manual arc welding or carbon dioxide gas shielded welding. In the end, after the simple mechanical cutting process (that is, turning the inner hole, outer edge, both ends of the surface and the pin key groove or planing keyway, etc.) and grinding burr to achieve the requirements of the spiral work diagram, that is, the vacuum extrusion molding work spiral .

5 Conclusions The use of cold-drawn spiral forming spiral method manufacturing vacuum extrusion machine compared with the general application of the method of molding spiral, has the following advantages: 61) Short production cycle, can ensure the production schedule.

2) The forming quality of the spiral surface is good, there are no defects such as pores, sand holes, and loose, and the working surface is smooth and smooth, and the spiral lead is guaranteed.

The production process is simple and no membranes are needed. Its low production cost is particularly suitable for the use of wall and floor tile manufacturers with poor machinery manufacturing capabilities.

The scope of application is particularly wide. By changing the length of the thrust rod, the size of the cold drawn forming mandrel and the vertical hydraulic jack, the spiral size of the vacuum extrusion molding machine can be obtained.

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