Rotary part self-adaptive follow-up tool system

Abstract

The invention relates to the technical field of machining tools, in particular to a rotary part self-adaptive follow-up tool system which comprises a mounting base and a rotary table, the mounting base is connected with a machining table of a rotary part machining tool, the rotary table is rotationally arranged at the top of the mounting base, and a positioning mechanism is rotationally arranged at the top of the rotary table. In the process that the rotating plate rotates along with the expansion shaft, the sliding table and the expansion driving lever are driven to rotate together, the expansion driving lever slides along the track of the arc-shaped groove, the circle center of the arc-shaped groove is located on the side, away from the center tray, of the expansion shaft, and therefore the expansion driving lever generates radial thrust on the expansion driving lever when the expansion driving lever slides in the second-stage expansion guide block; the sliding table is forced to slide in the length direction of the rotating plate, the positioning base and the positioning column are driven to move in the direction away from the center tray, the two-stage expansion effect is achieved, the inner supporting range is further enlarged, and inner supporting and positioning of a large-aperture valve are facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machining tooling, in particular to a rotary part adaptive follow-up tooling system. BACKGROUND

[0002] The valve adaptive follow-up tooling is an automatic device used in the process of valve machining, assembly, etc., which can automatically adjust the position, posture or parameter according to the characteristics of the valve or the changes of the working environment, so as to realize high-precision operation. In order to facilitate the machining of the outer part of the valve, the inner support tooling is generally used to machine the outer surface of the valve in the art. The existing inner support tooling adopts the structure of "fixed cone surface + single support block". The radial expansion stroke of the support block is directly determined by the taper and length of the center shaft. Once designed and formed, the maximum and minimum inner support diameters are locked. Most conventional toolings can only cover ±10%-15% of the inner diameter fluctuation (for example, a tooling with a nominal fit of DN100 can only adapt to DN90-DN110 in practice). It cannot meet the machining needs of cross-series and cross-specification valves. For example, a multi-specification valve production line for DN50-DN200 requires 4-5 sets of different toolings. Not only does it occupy storage space, but it also increases equipment investment costs. In view of this, we propose a rotary part adaptive follow-up tooling system to solve the above technical problems. SUMMARY

[0003] The present application provides the following technical scheme: a rotary part adaptive follow-up tooling system, comprising: A mounting base connected to the machining table of a rotary part machining machine; A turntable rotatably arranged on the top of the mounting base, wherein the top of the turntable is rotatably provided with a positioning mechanism; The positioning mechanism has a first expansion part and a second expansion part. The first expansion part includes a center tray and an expansion piece fixed on the center tray. The center tray is rotatably installed on the top of the turntable and is adapted to rotate the expansion piece for first expansion to expand the second expansion part and position the valve body.

[0004] As a preferred scheme of the present application, the bottom of the center tray is fixedly provided with a power shaft, the power shaft is connected to the mounting base through a rotating connecting piece, the center tray has three equally angularly distributed flanges, and the top of the center tray is equally angularly provided with three positioning grooves for accommodating the flanges. The flanges are embedded in the positioning grooves and are fixed by bolts. The bottom of the power shaft is provided with a power source, and the bottom of the power shaft is connected to the output shaft of the power source.

[0005] As a preferred scheme of the present application, the inside of the pick plate is provided with a vertical expansion shaft, the bottom of the expansion shaft is fixedly provided with a planetary gear, the top of the rotary table is fixedly provided with a sun gear, the planetary gear is engaged with the periphery of the sun gear, the top of the expansion shaft is fixedly provided with a rotating plate, the top of the rotating plate is slidably provided with a sliding table through a sliding guide along the length direction of the rotating plate, and the top of the sliding table is fixedly provided with a positioning base.

[0006] As a preferred scheme of the present application, the bottom of the sliding table is fixedly provided with an expansion lever, the side of the rotating plate close to the expansion lever is provided with a slot for accommodating the movement of the expansion lever, the top of the pick plate is fixedly provided with a secondary expansion guide, the top of the secondary expansion guide is provided with an arc-shaped slot for guiding the path of the expansion lever, the expansion lever is slidably arranged in the arc-shaped slot, the center of the arc-shaped slot is not concentric with the center of the expansion shaft, and the center of the arc-shaped slot is located on the side of the expansion shaft away from the center tray.

[0007] As a preferred scheme of the present application, the sliding guide comprises a linear sliding block fixedly arranged on the top of the rotating plate, and a linear guide slidably arranged in the linear sliding block, and the top of the linear guide is fixedly arranged on the bottom of the sliding table through bolts.

[0008] As a preferred scheme of the present application, the end of the positioning base away from the center tray is threadedly provided with an adjusting screw, the end of the sliding table away from the center tray is fixedly provided with an adjusting block, the adjusting screw is movably arranged in the adjusting block, a plurality of adjusting nuts are threadedly arranged on the adjusting screw, and the adjusting nuts are arranged on both sides of the adjusting block and abut against the side surface of the adjusting block.

[0009] As a preferred scheme of the present application, the inside of the pick plate is provided with a bearing mounting hole for accommodating the expansion shaft, the bearing mounting hole is provided with a center bearing, the expansion shaft is rotatably connected with the bearing mounting hole through the center bearing, and the top of the pick plate is detachably provided with a bearing pressing strip for pressing the center bearing in the bearing mounting hole through bolts.

[0010] As a preferred scheme of the present application, the top of the pick plate is fixedly provided with a limiting lever, the limiting lever is located on the side of the rotating plate away from the slot, and in the initial state, the outer surface of the limiting lever abuts against the side surface of the rotating plate for positioning the angle of the rotating plate.

[0011] As a preferred scheme of the present application, the periphery of the rotary table is fixedly provided with an outer gear ring, the outer gear ring is engaged with the gear of an external power source, and the gear of the power source is suitable for driving the rotary table to rotate.

[0012] As a preferred scheme of the present application, the top of the rotating table is fixedly provided with a sheet metal shell, the sheet metal shell is located at the periphery of the positioning mechanism, a plurality of the bottom of the cantilever plate is commonly provided with a sheet metal top cover, the sheet metal top cover is located at the top of the sheet metal shell, the sheet metal top cover and the sheet metal shell form a dustproof space for the positioning mechanism, and the top of the sheet metal top cover is provided with three tracking grooves corresponding to the positions of the three secondary expansion guide blocks.

[0013] Compared with the prior art, the present application has the following beneficial effects: 1. In the present application, after the driving source drives the power shaft to rotate, the power shaft drives the center tray, the cantilever plate, the expansion shaft and the planetary gear to rotate together, the planetary gear rotates along the periphery of the sun gear, the planetary gear generates autorotation and drives the expansion shaft to autorotate due to the meshing of the planetary gear and the sun gear, so that the rotating sliding table drives the positioning column to rotate together through the connection of the positioning base, and finally the three positioning columns are expanded to the periphery in a first level, and the three expanded positioning columns are used for supporting and positioning the inner wall of the valve body.

[0014] 2. In the present application, during the rotation of the rotating plate along with the expansion shaft, the rotating plate drives the sliding table and the expansion lever to rotate together, so that the expansion lever slides along the arc-shaped groove track, and the center of the arc-shaped groove is located at the side away from the center tray of the expansion shaft, so that the expansion lever generates a radial thrust during the sliding of the expansion lever inside the secondary expansion guide block, forcing the sliding table to slide along the length direction of the rotating plate, and driving the positioning base and the positioning column to move together away from the center tray, realizing the secondary expansion effect, further increasing the supporting range, and being beneficial to supporting and positioning the valve body with a large aperture.

[0015] 3. In the present application, the adjusting nuts on both sides of the adjusting block are adjusted, so that the position of the positioning base can be adjusted through the tension of the adjusting screw, so as to compensate for the problem that the distances from the three positioning bases to the center of the center tray are inconsistent due to error accuracy during processing and assembly, so that when the three positioning columns support the valve body, the center of the valve body is concentric with the machine tool processing shaft, and the processing accuracy is improved.

[0016] 4. In the present application, the power source drives the power shaft to rotate reversely, so that the first expansion part and the secondary expansion part reset, and finally the cantilever plate rotates with the reversely rotating center tray and touches the outer surface of the limit stop rod, that is, the positioning mechanism returns to the initial state, so as to prevent the reverse angle from being too large during the resetting process of the power source driving the power shaft. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present application; Figure 2 It is a schematic diagram of the internal structure of the sheet metal shell in the present application; Figure 3Structure diagram of the mounting base in the application; Figure 4 Structure diagram of the positioning mechanism in the application; Figure 5 Structure diagram of the mounting base in the application; Figure 4 Structure diagram of the mounting base in the application; Figure 6 Structure diagram of the mounting base in the application; Figure 5 Structure diagram of the mounting base in the application; Figure 7 Structure diagram of the mounting base in the application; Figure 8 Structure diagram of the mounting base in the application; Figure 9 Structure diagram of the mounting base in the application;

[0018] In the figure: 100, mounting base; 200, rotary table; 301, center tray; 302, positioning groove; 303, pick plate; 3031, bearing mounting hole; 304, expansion shaft; 305, planetary gear; 306, sun gear; 307, rotating plate; 3071, accommodation groove; 308, sliding table; 309, positioning base; 3010, positioning column; 3011, expansion lever; 3012, secondary expansion guide block; 3013, arc-shaped groove; 3014, power shaft; 3015, linear sliding block; 3016, linear guide rail; 3017, adjusting block; 3018, adjusting screw; 3019, adjusting nut; 3020, center bearing; 3021, bearing pressing strip; 3022, limit stop lever; 400, outer gear ring; 500, sheet metal shell; 501, sheet metal top cover; 502, tracking groove. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0020] Please refer to Figures 1-9 The technical solutions provided by the application specifically include the following embodiments: The application discloses a rotary part adaptive follow-up tool system, which comprises a mounting base 100 and a rotary table 200, the mounting base 100 is connected with a machining table of a rotary part machining machine tool, the rotary table 200 is rotationally arranged on the top of the mounting base 100, a positioning mechanism is rotationally arranged on the top of the rotary table 200, the positioning mechanism comprises a first expansion part and a second expansion part, the first expansion part comprises a center tray 301 and an expansion piece fixed on the center tray 301, the center tray 301 is rotationally arranged on the top of the rotary table 200, the center tray 301 is adapted to rotate the expansion piece to expand the first expansion part, so that the second expansion part is expanded, and a valve body is positioned and machined.

[0021] Further, with specific reference to Figure 4 、 Figure 5 、 Figure 7 、 Figure 8 illustrated: A power shaft 3014 is fixedly arranged on the bottom of the center tray 301, the power shaft 3014 is connected with the mounting base 100 through a rotating connecting piece, the rotating connecting piece can be a plane bearing with a suitable specification, so as to ensure the stability of the connection between the power shaft 3014 and the mounting base 100, the center tray 301 is provided with three pick plates 303 which are distributed at equal angles, three positioning grooves 302 for accommodating the pick plates 303 are arranged on the top of the center tray 301 at equal angles, the pick plates 303 are embedded in the positioning grooves 302, so that the pick plates 303 cannot shake left and right, and the pick plates 303 are fixed through bolts, so that the pick plates 303 cannot be loosened, a power source is arranged on the bottom of the power shaft 3014, the bottom of the power shaft 3014 is connected with an output shaft of the power source, and the power source can be a motor or other driving equipment.

[0022] The expansion shafts 304 are arranged in the picking plate 303, the bottom of the expansion shafts 304 is fixedly installed with the planetary gears 305, the top of the rotating table 200 is fixedly installed with a sun gear 306, the planetary gears 305 are engaged with the outer periphery of the sun gear 306, after the driving power shaft 3014 is driven to rotate by the driving source, the center tray 301, the picking plate 303, the expansion shaft 304 and the planetary gears 305 rotate together, the planetary gears 305 rotate along the outer periphery of the sun gear 306, the planetary gears 305 generate autorotation and drive the expansion shaft 304 to autorotate due to the engagement of the planetary gears 305 and the sun gear 306, the top of the expansion shaft 304 is fixedly installed with the rotating plate 307, so that the rotating plate 307 rotates with the expansion shaft 304, the top of the rotating plate 307 is slidably installed with the sliding table 308 along the length direction of the rotating plate 307 through the sliding guide, so that the sliding table 308 rotates with the rotating plate 307 through the connection of the guide sliding part, the top of the sliding table 308 is fixedly installed with the positioning base 309, the top of the positioning base 309 is fixedly installed with the positioning column 3010, so that the rotating sliding table 308 drives the positioning column 3010 to rotate through the connection of the positioning base 309, finally, the three positioning columns 3010 perform one-stage expansion to the outer periphery, and the three expanded positioning columns 3010 are used for supporting and positioning the inner wall of the valve body.

[0023] Further, with specific reference to Figure 8 、 Figure 9 shown: The sliding guide comprises a linear slider 3015 fixedly installed on the top of the rotating plate 307, and a linear guide rail 3016 slidably installed in the linear slider 3015, the top of the linear guide rail 3016 being fastened and installed on the bottom of the sliding table 308 by bolts, the sliding table 308 being accurately limited to be slidable along the length direction of the rotating plate 307 through the sliding guide action of the linear slider 3015 and the linear guide rail 3016, the bottom of the sliding table 308 being fixedly installed with the expansion lever 3011, the side of the rotating plate 307 close to the expansion lever 3011 being provided with a displacement slot 3071 for accommodating the movement of the expansion lever 3011, the displacement slot 3071 being provided to avoid the interference between the expansion lever 3011 and the main body of the rotating plate 307 during the sliding of the expansion lever 3011 along the length direction of the rotating plate 307, the top of the pick plate 303 being fixedly installed with a secondary expansion guide block 3012, the top of the secondary expansion guide block 3012 being provided with an arc-shaped slot 3013 for path guiding of the expansion lever 3011, the expansion lever 3011 being slidably arranged in the arc-shaped slot 3013, the rotating plate 307 driving the sliding table 308 and the expansion lever 3011 to rotate together during the rotation of the expansion shaft 304, so that the expansion lever 3011 slides along the trajectory of the arc-shaped slot 3013, the center of the arc-shaped slot 3013 being different from the center of the expansion shaft 304, and the center of the arc-shaped slot 3013 being located on the side of the expansion shaft 304 away from the center tray 301, so that the expansion lever 3011 generates a radial thrust on the expansion lever 3011 during the sliding of the expansion lever 3011 in the secondary expansion guide block 3012, forcing the sliding table 308 to slide along the length direction of the rotating plate 307, and driving the positioning base 309 and the positioning column 3010 to move together away from the center tray 301, realizing the secondary expansion effect, further increasing the supporting range, and being beneficial to the supporting and positioning of the valve with a large diameter.

[0024] Further, with specific reference to Figure 9 shown: An adjusting screw 3018 is threaded onto the end of the positioning base 309 furthest from the central tray 301. An adjusting block 3017 is fixedly mounted onto the end of the slide table 308 furthest from the central tray 301. The adjusting screw 3018 moves through the interior of the adjusting block 3017, and several adjusting nuts 3019 are threaded onto the adjusting screw 3018. These nuts are evenly distributed on both sides of the adjusting block 3017 and abut against its sides. By adjusting the adjusting nuts 3019 on both sides of the adjusting block 3017, the position of the positioning base 309 can be adjusted by the tension of the adjusting screw 3018. It is important to note that a groove needs to be cut into the top of the positioning base 309, and bolts are inserted into the groove to secure it to the slide table 308. The threaded groove facilitates the movement of the positioning base 309 without interference from the fixing bolts. At the same time, the groove and bolts provide guidance for the positioning base 309 along the adjustment direction. Ultimately, the position of the positioning base 309 can be adjusted to compensate for the problem of inconsistent distances between the three positioning bases 309 and the center of the central tray 301 due to errors in machining and assembly. This ensures that when the three positioning columns 3010 support the valve body, the center of the valve body is concentric with the machining axis of the machine tool, thus improving machining accuracy.

[0025] For further details, please refer to [link / reference]. Figure 8 As shown: The cantilever plate 303 has a bearing mounting hole 3031 inside to accommodate the expansion shaft 304. A central bearing 3020 is installed inside the bearing mounting hole 3031. The expansion shaft 304 is rotatably connected to the bearing mounting hole 3031 through the central bearing 3020. The central bearing 3020 makes the rotatable connection between the expansion shaft 304 and the bearing mounting hole 3031 more stable, and at the same time, the rotational damping of the expansion shaft 304 is smaller. Therefore, the wear of the expansion shaft 304 will be less. A bearing pressure strip 3021 is detachably installed on the top of the cantilever plate 303 by bolts to press the central bearing 3020 into the bearing mounting hole 3031, so that the central bearing 3020 is not easy to climb out of the bearing mounting hole 3031, and is also not easy to wobble inside the bearing mounting hole 3031.

[0026] For further details, please refer to [link / reference]. Figure 5 As shown: The top of the pick plate 303 is fixedly provided with a limiting rod 3022, which is located on the side of the rotating plate 307 away from the accommodation groove 3071, and in the initial state, the outer surface of the limiting rod 3022 abuts against the side surface of the rotating plate 307, which is used for the angle positioning of the rotating plate 307 in the initial state. After processing, the power source drives the power shaft 3014 to rotate reversely, so that the primary expansion part and the secondary expansion part reset, and finally the pick plate 303 rotates with the reversely rotating central tray 301 to abut against the outer surface of the limiting rod 3022, that is, the positioning mechanism returns to the initial state, so as to prevent the power source from driving the power shaft 3014 to reset the angle excessively.

[0027] Further, with reference to Figure 2 , it is shown that: The rotating table 200 is fixedly provided with an outer gear ring 400 on the periphery, the outer gear ring 400 is engaged with an external power source gear, and is suitable for driving the outer gear ring 400 to rotate by the power source gear. The power source can be a motor. The outer gear ring 400 is driven to rotate by the power source, further drives the rotating table 200 to rotate on the top of the mounting base 100, and then drives the valve positioned by the inner support to rotate, so as to adapt the valve to the machining shaft of the machining machine tool.

[0028] Further, with reference to Figure 1 , it is shown that: The rotating table 200 is fixedly provided with a sheet metal shell 500 on the top, the sheet metal shell 500 is located on the periphery of the positioning mechanism, a sheet metal top cover 501 is commonly provided on the bottom of the plurality of pick plates 303, the sheet metal top cover 501 is located on the top of the sheet metal shell 500, and the sheet metal top cover 501 and the sheet metal shell 500 form a dustproof space for the positioning mechanism. The dustproof space can isolate the positioning mechanism inside from dust to a certain extent. Three tracking grooves 502 corresponding to the positions of the three secondary expansion guide blocks 3012 are provided on the top of the sheet metal top cover 501, which are adapted to the track of the arc-shaped groove 3013. The provision of the tracking grooves 502 can prevent the sheet metal top cover 501 from interfering with the expansion lever 3011 during the sliding of the expansion lever 3011 along the secondary expansion guide block 3012.

[0029] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and deformations can be made to the embodiments without departing from the principles and spirits of the present application.

Claims

1. An adaptive follow-up tooling system for rotating parts, characterized in that: include: Mounting base (100) is connected to the machining table of a rotary parts processing machine tool; A turntable (200) is rotatably mounted on the top of the mounting base (100), and a positioning mechanism is rotatably mounted on the top of the turntable (200); The positioning mechanism has a primary expansion section and a secondary expansion section. The primary expansion section includes a central tray (301) and an expansion member fixed on the central tray (301). The central tray (301) is rotatably mounted on the top of the turntable (200), which is suitable for the central tray (301) to rotate and drive the expansion member to rotate for primary expansion, so that the secondary expansion section expands and positions the valve body.

2. The adaptive follow-up tooling system for rotating parts according to claim 1, characterized in that: A power shaft (3014) is fixedly installed at the bottom of the central tray (301). The power shaft (3014) is connected to the mounting base (100) through a rotating connector. The central tray (301) has three cantilever plates (303) distributed at equal angles. The top of the central tray (301) is provided with three positioning grooves (302) at equal angles for accommodating the cantilever plates (303). The cantilever plates (303) are embedded in the positioning grooves (302) and fixed by bolts. A power source is provided at the bottom of the power shaft (3014), and the bottom of the power shaft (3014) is connected to the output shaft of the power source.

3. The adaptive follow-up tooling system for rotating parts according to claim 2, characterized in that: The cantilever plate (303) is rotatably provided with a vertical expansion shaft (304) inside. The bottom of the expansion shaft (304) is fixedly installed with a planetary gear (305). The top of the turntable (200) is fixedly installed with a sun gear (306). The planetary gears (305) are all meshed with the periphery of the sun gear (306). The top of the expansion shaft (304) is fixedly installed with a rotating plate (307). The top of the rotating plate (307) is slidably installed with a slide table (308) along the length direction of the rotating plate (307) through a sliding guide. The top of the slide table (308) is fixedly installed with a positioning base (309). The top of the positioning base (309) is fixedly installed with a positioning column (3010).

4. The adaptive follow-up tooling system for rotating parts according to claim 3, characterized in that: An expansion lever (3011) is fixedly installed at the bottom of the slide (308). A clearance groove (3071) for accommodating the movement of the expansion lever (3011) is provided on the side of the rotating plate (307) near the expansion lever (3011). A secondary expansion guide block (3012) is fixedly installed at the top of the pick plate (303). An arc-shaped groove (3013) for guiding the path of the expansion lever (3011) is provided through the top of the secondary expansion guide block (3012). The expansion lever (3011) is slidably disposed inside the arc-shaped groove (3013). The center of the arc-shaped groove (3013) is not concentric with the center of the expansion shaft (304), and the center of the arc-shaped groove (3013) is located on the side of the expansion shaft (304) away from the central tray (301).

5. The adaptive follow-up tooling system for rotating parts according to claim 4, characterized in that: The sliding guide includes a linear slider (3015) fixedly installed on the top of the rotating plate (307) and a linear guide rail (3016) slidably installed inside the linear slider (3015). The top of the linear guide rail (3016) is fastened to the bottom of the slide table (308) by bolts.

6. The adaptive follow-up tooling system for rotating parts according to claim 5, characterized in that: An adjusting screw (3018) is threaded onto one end of the positioning base (309) away from the central tray (301). An adjusting block (3017) is fixedly installed on one end of the slide (308) away from the central tray (301). The adjusting screw (3018) moves through the interior of the adjusting block (3017). Several adjusting nuts (3019) are threaded onto the adjusting screw (3018). The several adjusting nuts (3019) are evenly distributed on both sides of the adjusting block (3017) and abut against the side of the adjusting block (3017).

7. The adaptive follow-up tooling system for rotating parts according to claim 6, characterized in that: The cantilever plate (303) has a bearing mounting hole (3031) inside to accommodate the expansion shaft (304). A central bearing (3020) is provided inside the bearing mounting hole (3031). The expansion shaft (304) is rotatably connected to the bearing mounting hole (3031) through the central bearing (3020). A bearing pressure strip (3021) is detachably installed on the top of the cantilever plate (303) by bolts to press the central bearing (3020) inside the bearing mounting hole (3031).

8. The adaptive follow-up tooling system for rotating parts according to claim 7, characterized in that: A limiting rod (3022) is fixedly installed on the top of the cantilever plate (303). The limiting rod (3022) is located on the side of the rotating plate (307) away from the clearance groove (3071). In the initial state, the outer surface of the limiting rod (3022) abuts against the side of the rotating plate (307) for the initial angle positioning of the rotating plate (307).

9. The adaptive follow-up tooling system for rotating parts according to claim 8, characterized in that: An external gear ring (400) is fixedly installed on the periphery of the turntable (200). The external gear ring (400) meshes with an external power source gear and is suitable for the power source gear to drive the external gear ring (400) to rotate.

10. The adaptive follow-up tooling system for rotating parts according to claim 9, characterized in that: A sheet metal shell (500) is fixedly installed on the top of the turntable (200). The sheet metal shell (500) is located around the positioning mechanism. A sheet metal top cover (501) is installed on the bottom of multiple cantilever plates (303). The sheet metal top cover (501) is located on the top of the sheet metal shell (500). The sheet metal top cover (501) and the sheet metal shell (500) form a dustproof space for the positioning mechanism. Three tracking grooves (502) that are adapted to the trajectory of the arc groove (3013) are opened at the top of the sheet metal top cover (501) corresponding to the positions of the three secondary expansion guide blocks (3012).

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