A high-stability composite wheel hub processing machine tool

Abstract

The application discloses a high-stability composite wheel hub processing machine tool and relates to the technical field of machine tool processing. The machine tool comprises a bed body, a mounting top connected to the bed body through a multi-shaft linkage mechanism, a mounting bottom plate fixed to the bottom of the mounting top, a plurality of second sliding grooves formed in the upper end of the mounting bottom plate, a fixing column installed at the central position of the upper end of the mounting bottom plate, a first gear connected to the outer end groove of the fixing column through a motor, a first internal tooth ring meshedly connected to the outer end of the first gear, and an adjusting plate connected to the lower end of the first internal tooth ring. The mounting bottom plate, the adjusting plate and the mounting sliding block are matched to set a plurality of drill bits, and the plurality of drill bits can be synchronously adjusted at corresponding positions according to the punching positions of wheel hub bolt holes of different specifications. The adjusting assembly and the oil component are matched to quickly switch and adjust the positions of the plurality of drill bits and the polishing head when the bolt holes are polished.

Description

Technical Field

[0001] This invention relates to the field of machine tool processing technology, specifically to a machine tool for processing highly stable composite wheel hubs. Background Technology

[0002] Composite wheels, with their composite material properties, can improve stability during use. When processing composite wheels, a machining tool is usually required to perform turning, milling, drilling and grinding operations on the wheel on a single machine, which reduces the number of clamping operations and improves production efficiency.

[0003] However, in actual use, existing machine tools have varying distances between bolt holes and the center of the wheel hub for drilling bolt holes and deburring the hole walls. Before drilling, the machine tool's control computer parameters need to be adjusted according to the drilling positions on different wheel hubs. Furthermore, the traditional single drill and grinding head design requires changing the drill and grinding heads during drilling and grinding, and the drilling sequence and stroke parameters also need to be adjusted synchronously. This results in overly complex programs and numerous production steps for existing machine tools, impacting production efficiency and processing stability. Therefore, it is inconvenient to design multiple drill and grinding heads and adjust the dimensional program to adapt the drilling positions for different wheel hub specifications, or to optimize the drilling and grinding steps through mechanical switching of drill and grinding heads. Summary of the Invention

[0004] The purpose of this invention is to provide a high-stability composite wheel hub machining machine tool to solve the problems mentioned in the background art, such as the inconvenience of existing machining machines in adapting drilling positions to different wheel rail specifications by designing multiple drill bits and grinding heads and coordinating simple size program adjustments, as well as the problem of optimizing drilling and grinding steps by mechanically switching drill bits and grinding heads. The technical solution of this invention addresses the problem of the overly simplistic nature of existing technical solutions and provides a solution that is significantly different from existing technologies.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a machine tool for processing high-stability composite hubs, comprising a bed, wherein the bed is connected to a mounting top via a multi-axis linkage mechanism, a mounting base plate is fixed to the bottom of the mounting top, the upper end of the mounting base plate is provided with multiple second sliding grooves, a fixed column is mounted at the center of the upper end of the mounting base plate, a first gear is connected to the outer end of the fixed column via a motor in the groove, the outer end of the first gear is meshed with a first internal gear ring, the lower end of the first internal gear ring is connected to an adjusting plate, the adjusting plate is rotatably mounted on the outside of the fixed column via a bearing, the upper end of the adjusting plate is provided with multiple first sliding grooves, a first column is slidably connected in the first sliding groove, the lower end of the first column is connected to a mounting slider, the mounting slider is slidably disposed inside the second sliding groove, multiple outer end protrusions of the mounting slider are connected to second gears via a motor, the outer ends of the second gears are meshed with first gear rings, the first gear rings are mounted on an adjusting assembly, the adjusting assembly is disposed on the mounting slider;

[0006] An oil hydraulic assembly is disposed between the mounting base plate and the adjustment assembly, and the oil hydraulic assembly is used for adjusting the rotation of the adjustment assembly;

[0007] The oil assembly includes a first oil tank, which is fixed to the bottom of the groove at the top of the mounting top. A first plug is slidably connected to the inner cavity of the first oil tank. An electric actuator is connected to the outer end of the first plug, which is fixed to the bottom of the groove at the top of the mounting top. The inner cavity of the first oil tank is connected to multiple second oil tanks through multiple hoses. The second oil tank is fixed to the top of the protrusion on the left side of the mounting slider. A second plug is slidably connected to the inner cavity of the second oil tank through a spring. A second post is connected to the outer end of the second plug through a protrusion. The second post is rotatably mounted on the top of the protrusion on the left side of the mounting slider through a bearing.

[0008] Preferably, the plurality of first slides are opened at equal angles, and the number of the plurality of first slides corresponds to the number of second slides.

[0009] Preferably, the adjusting assembly includes a rotating column, which is rotatably disposed inside the mounting slider slot. Rotary tubes are slidably disposed within the two slots of the rotating column. Connecting columns are rotatably mounted on the inner sides of both rotating tubes via bearings. A first toothed ring is connected to the outer top of each connecting column. A second toothed ring is mounted on the outer side of the top of the rotating column. A mounting plate is fixed to the top of the rotating column. Adjusting toothed sleeves are rotatably connected to the two holes of the mounting plate via bearings. Both adjusting toothed sleeves are disposed outside the rotating tubes. A second internal toothed ring is disposed outside the two adjusting toothed sleeves. The second internal toothed ring is fixed to a protrusion on the outer side of the mounting slider. A first toothed disc is connected to the outer side of the second toothed ring, and the first toothed disc is mounted on the oil assembly.

[0010] Preferably, both of the two rotating tubes have threaded grooves on their outer sides, and the two rotating tubes are slidably connected to the inner protrusions of the two adjusting sleeves through the threaded grooves.

[0011] Preferably, the two outer teeth of the rotating tube are designed with one upper and one lower, and the inner side of the second tooth ring meshes with the lower outer tooth of one of the rotating tubes.

[0012] Preferably, a drill bit and a grinding head are respectively installed at the lower ends of the two connecting columns, and the diameter of the first toothed disc is larger than the diameter of the second toothed ring.

[0013] Preferably, a first toothed disc is installed on the outer side of the top of the second column.

[0014] Preferably, the No. 2 oil tank and the No. 2 plug are designed in an arc shape, and the center of the arc design of the No. 2 oil tank and the No. 2 plug corresponds to the center of the No. 2 column.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] This invention uses a first gear to drive a first internal gear ring and an adjusting plate to rotate and adjust the position of the first slide groove. When the first slide groove is rotated and adjusted, a first column drives a mounting slider to adjust its position in the second slide groove, so that the drill bit connecting column is adjusted to the corresponding drilling position. This allows multiple drill bits to be synchronously adjusted according to the drilling positions of different specifications of wheel hub bolt holes. This optimizes the drilling processing steps and dimensional parameter adjustments in the control computer program, improves the drilling efficiency for multiple bolt holes of different specifications of wheel hubs, and enhances the stability during drilling.

[0017] This invention, through the coordination of oil between a primary oil tank and multiple secondary oil tanks, enables the secondary plug to synchronously drive the secondary column to rotate. This, in turn, drives the secondary gear ring, rotating column, mounting plate, adjusting gear sleeve, and connecting column to rotate synchronously via a first gear disc. This completes the positional switching between the drill bit connecting column and the grinding head connecting column. Simultaneously, the linkage between the secondary internal gear ring and the two adjusting gear sleeves allows the two rotating tubes to move vertically relative to each other within the two adjusting gear sleeves, completing the extension and retraction adjustment of the drill bit connecting column and the grinding head connecting column. This enables rapid switching between the drill bit and the grinding head after hub drilling is completed, optimizing the adjustment of grinding processing steps and movement parameters in the control computer program, further improving production efficiency and stability. Attached Figure Description

[0018] Figure 1 This is a front view schematic diagram of the mounting top and mounting base of the present invention;

[0019] Figure 2 This is a schematic diagram of the overall front view of the present invention;

[0020] Figure 3This is a schematic diagram of the internal structure of the present invention, viewed from the top section.

[0021] Figure 4 This is a schematic diagram showing the disassembled structure of the mounting base plate, fixing column, first gear, and adjusting plate of the present invention.

[0022] Figure 5 This is a schematic diagram of the mounting base plate and mounting slider structure of the present invention;

[0023] Figure 6 This is a schematic diagram of the mounting slider and adjustment assembly structure of the present invention;

[0024] Figure 7 This is a schematic diagram of the disassembled structure of the mounting slider and adjustment components of the present invention;

[0025] Figure 8 This is a schematic diagram of the rotating column, mounting plate, adjusting gear sleeve, and No. 2 internal gear ring of the present invention;

[0026] Figure 9 This is a cross-sectional view of the oil component of the present invention;

[0027] Figure 10 This is a schematic diagram of the No. 2 oil tank and the No. 2 plug of the present invention.

[0028] In the diagram: 1. Bed; 2. Multi-axis linkage mechanism; 3. Mounting top; 4. Mounting base plate; 5. Fixed column; 6. First gear; 7. No. 1 internal gear ring; 8. Adjusting plate; 9. First slide groove; 10. No. 1 column; 11. Mounting slider; 12. Second slide groove; 13. Second gear; 14. First gear ring; 15. Adjusting assembly; 151. Rotating column; 152. Second gear ring; 153. Rotating pipe; 154. Connecting column; 155. Adjusting gear sleeve; 156. Mounting plate; 157. First gear disc; 158. No. 2 internal gear ring; 16. Oil assembly; 161. No. 1 oil tank; 162. No. 1 plug; 163. Electric actuator; 164. No. 2 oil tank; 165. No. 2 plug; 166. No. 2 column; 171. Drill bit; 172. Grinding head. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] Please see Figures 1 to 6This invention provides a technical solution: a high-stability composite wheel hub processing machine tool, including a bed 1, the bed 1 being connected to a mounting top 3 via a multi-axis linkage mechanism 2, a mounting base plate 4 fixed to the bottom of the mounting top 3, a plurality of second sliding grooves 12 being formed on the upper end of the mounting base plate 4, a fixing column 5 being installed at the center of the upper end of the mounting base plate 4, a first gear 6 being connected to a groove at the outer end of the fixing column 5 via a motor, a first internal gear ring 7 being meshed at the outer end of the first gear 6, an adjusting plate 8 being connected to the lower end of the first internal gear ring 7, the adjusting plate 8 being rotatably mounted on the outside of the fixing column 5 via a bearing, and a plurality of first sliding grooves 9 being formed on the upper end of the adjusting plate 8. All are inclined at equal angles. The number of multiple first slide grooves 9 corresponds to the number of second slide grooves 12. A first column 10 is slidably connected in the first slide groove 9. The lower end of the first column 10 is connected to a mounting slider 11. The mounting slider 11 is slidably disposed inside the second slide groove 12. The outer end protrusions of multiple mounting sliders 11 are connected to a second gear 13 through a motor. The outer end of the second gear 13 is meshed with a first gear ring 14. The first gear ring 14 is mounted on the adjustment component 15. The adjustment component 15 is disposed on the mounting slider 11. The oil component 16 is disposed between the mounting base plate 4 and the adjustment component 15. The oil component 16 is used to adjust the rotation of the adjustment component 15.

[0032] According to the drilling positions of different specifications of wheel hub bolt holes, when adjusting the position of drill bit 171, the control system of bed 1 turns on the motor connected to the first gear 6, and the first gear 6 drives the first internal gear ring 7 and the adjusting plate 8 to rotate and adjust the position of the first slide groove 9. When the first slide groove 9 is rotated and adjusted, the first column 10 drives the mounting slider 11 to adjust its position in the second slide groove 12, so that the connecting column 154 on drill bit 171 is adjusted to the corresponding drilling position, and the synchronous adjustment of the corresponding positions of multiple drill bits 171 is completed.

[0033] Example 2

[0034] Based on Example 1, please refer to Figures 1 to 10The adjusting component 15 is mounted on the mounting slider 11. The adjusting component 15 includes a rotating column 151, which is rotatably mounted inside the slot of the mounting slider 11. Rotary tubes 153 are slidably mounted in the two slots of the rotating column 151. Connecting columns 154 are rotatably mounted on the inner sides of both rotating tubes 153 via bearings. A first toothed ring 14 is connected to the outer top of the connecting column 154. A second toothed ring 152 is mounted on the outer top of the rotating column 151. The outer teeth of the two rotating tubes 153 are designed with one upper and one lower tooth. The inner side of the second toothed ring 152 meshes with the lower outer tooth of one of the rotating tubes 153. A mounting plate 156 is fixed to the top of the rotating column 151. Both holes of the mounting plate 156 are connected to... The bearing is rotatably connected to an adjusting gear sleeve 155. Both adjusting gear sleeves 155 are located on the outside of the rotating tube 153. Both rotating tubes 153 have threaded grooves on their outer sides. The two rotating tubes 153 are slidably connected to the inner protrusions of the two adjusting gear sleeves 155 through the threaded grooves. A second internal gear ring 158 is provided on the outside of the two adjusting gear sleeves 155. The second internal gear ring 158 is fixed on the outer protrusion of the mounting slider 11. A first gear disc 157 is connected to the outside of the second gear ring 152. The first gear disc 157 is installed on the oil assembly 16. A drill bit 171 and a grinding head 172 are respectively installed at the lower ends of the two connecting columns 154. The diameter of the first gear disc 157 is larger than the diameter of the second gear ring 152.

[0035] The oil assembly 16 is disposed between the mounting base plate 4 and the adjusting assembly 15. The oil assembly 16 includes a primary oil tank 161, which is fixed to the bottom of the top groove of the mounting top 3. A primary plug 162 is slidably connected to the inner cavity of the primary oil tank 161. An electric actuator 163 is connected to the outer end of the primary plug 162 and is fixed to the bottom of the top groove of the mounting top 3. The inner cavity of the primary oil tank 161 is connected to multiple secondary oil tanks 164 through multiple hoses. The secondary oil tanks 164 are fixed to the top of the left protrusion of the mounting slider 11. The inner cavity of the second oil tank 164 is slidably connected to the second plug 165 by a spring. The second plug 165 is connected to the second column 166 by a protrusion on its outer end. The second column 166 is rotatably mounted on the top of the protrusion on the left side of the mounting slider 11 by a bearing. The second oil tank 164 and the second plug 165 are designed in an arc shape. The center of the arc design of the second oil tank 164 and the second plug 165 corresponds to the center of the second column 166. The first toothed disc 157 is installed on the outer side of the top of the second column 166. The oil assembly 16 is used to adjust the rotation of the adjustment assembly 15.

[0036] After the bolt holes in the wheel hub are drilled, and deburring is required, oil from the first oil tank 161 is forced into multiple second oil tanks 164. The increased oil level in the second oil tanks 164 pushes the second plug 165 to compress the spring, causing it to slide to one side within the second oil tank 164. This causes the second plug 165 to synchronously rotate the second column 166, which in turn drives the second gear ring 152, the rotating column 151, and the mounting plate 15 via the first gear disc 157. 6. Adjust the gear sleeve 155 and the connecting column 154 to rotate synchronously, so as to complete the position swap of the connecting column 154 on the drill bit 171 and the connecting column 154 on the grinding head 172. At the same time, with the linkage between the second internal gear ring 158 and the two adjusting gear sleeves 155, the two rotating tubes 153 move up and down relative to each other in the two adjusting gear sleeves 155 respectively, so as to complete the extension and retraction adjustment of the positions of the connecting column 154 on the drill bit 171 and the connecting column 154 on the grinding head 172.

[0037] Working principle: When using this high-stability composite hub processing machine tool, the operator first fixes the composite hub to be processed onto the fixing mechanism on the machine body 1. Then, according to the drilling position of the bolt holes of different specifications of hubs, the position of the drill bit 171 is adjusted accordingly. The control system of the machine body 1 turns on the motor connected to the first gear 6, and the first gear 6 drives the first internal gear ring 7 and the adjusting plate 8 to rotate and adjust the position of the first slide groove 9. When the first slide groove 9 is rotated and adjusted, the first column 10 drives the mounting slider 11 to adjust its position in the second slide groove 12, so that the connecting column 154 on the drill bit 171 is adjusted to the corresponding drilling position, and the synchronous adjustment of the corresponding positions of multiple drill bits 171 is completed. Then, the motor connected to the second gear 13 is turned on, and the first gear ring 14 and the connecting column 154 on the drill bit 171 are rotated. The multi-axis linkage mechanism 2 adjusts the position of the mounting top 3 downward, so that the connecting column 154 on the drill bit 171 moves downward and completes the drilling of the bolt holes of the hub.

[0038] After the bolt holes in the wheel hub are drilled, and the bolt holes need to be deburred, the multi-axis linkage mechanism 2 moves upward to reset and adjust the position of the mounting top 3, and shuts off the motor connected to the second gear 13. At the same time, the electric push rod 163 is turned on to push the first plug 162 backward in the first oil tank 161, squeezing the oil in the first oil tank 161 into multiple second oil tanks 164. The oil in the second oil tanks 164 increases, pushing the second plug 165 to squeeze the spring and slide to one side in the second oil tank 164. The protrusion at one end of the second plug 165 drives the second column 166 and the first gear plate 157 to rotate. When the first gear plate 157 rotates, it drives the second gear ring 152 and the rotating column 151 to adjust their positions in the slot of the mounting slider 11, and the second plug... When the No. 2 oil tank 164 moves to its maximum position, the connecting post 154 on the drill bit 171 and the connecting post 154 on the grinding head 172 exchange positions. At the same time, during the above process, when the rotating post 151 rotates, it synchronously drives the mounting plate 156 and the adjusting gear sleeve 155 to rotate synchronously to adjust their positions. Meanwhile, when the adjusting gear sleeve 155 with the outer lower tooth rotates, it meshes with the No. 2 inner tooth ring 158, and rotates synchronously, driving the other meshing adjusting gear sleeve 155 to rotate in the opposite direction. When the two adjusting gear sleeves 155 rotate in opposite directions, they respectively drive the rotating tube 153 corresponding to the drill bit 171 to move upward and the rotating tube 153 corresponding to the grinding head 172 to move downward, completing the extension and retraction adjustment of the positions of the connecting post 154 on the drill bit 171 and the connecting post 154 on the grinding head 172.

[0039] After the positions of the drill bit 171 and the grinding head 172 are adjusted, the motor connected to the second gear 13 is turned on, which drives the first gear ring 14 and the connecting column 154 of the grinding head 172 to rotate in the rotating tube 153. The multi-axis linkage mechanism 2 drives the mounting top 3 to move downward, thus completing the grinding step of the grinding head 172 on the wheel hub bolt hole.

[0040] Contents not described in detail in this specification are prior art known to those skilled in the art. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Terms such as "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail" indicate orientations or positional relationships based on the accompanying drawings, and are used only for ease of description and simplification, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A machine tool for processing high-stability composite wheel hubs, characterized in that: The system includes a bed frame (1), which is connected to a mounting top (3) via a multi-axis linkage mechanism (2). A mounting base plate (4) is fixed to the bottom of the mounting top (3). The mounting base plate (4) has multiple second sliding grooves (12) on its upper end. A fixing column (5) is installed at the center of the upper end of the mounting base plate (4). A first gear (6) is connected to the groove at the outer end of the fixing column (5) via a motor. A first internal gear ring (7) is meshed with the outer end of the first gear (6). An adjusting plate (8) is connected to the lower end of the first internal gear ring (7). The adjusting plate (8) is rotatably mounted on the fixing column (5) via a bearing. On the outside, the upper end of the adjustment plate (8) is provided with a plurality of first slide grooves (9), a first column (10) is slidably connected in the first slide groove (9), and the lower end of the first column (10) is connected to an installation slider (11). The installation slider (11) is slidably disposed in the inner side of the second slide groove (12). The outer end protrusions of the plurality of installation sliders (11) are connected to a second gear (13) through a motor. The outer end of the second gear (13) is meshed with a first toothed ring (14). The first toothed ring (14) is mounted on the adjustment assembly (15). The adjustment assembly (15) is disposed on the installation slider (11). Oil assembly (16) is disposed between mounting base plate (4) and adjustment assembly (15), and the oil assembly (16) is used to adjust the rotation of adjustment assembly (15); The adjusting assembly (15) includes a rotating column (151), which is rotatably disposed inside the slot of the mounting slider (11). Rotary tubes (153) are slidably disposed within the two slots of the rotating column (151). Connecting columns (154) are rotatably mounted on the inner sides of both rotating tubes (153) via bearings. A first toothed ring (14) is connected to the outer top end of the connecting column (154). A second toothed ring (152) is mounted on the outer top end of the rotating column (151). A mounting plate is fixed to the top of the rotating column (151). (156) The two holes of the mounting plate (156) are rotatably connected to the adjusting sleeves (155) by bearings. The two adjusting sleeves (155) are both set on the outside of the rotating tube (153). The two adjusting sleeves (155) are provided with the second internal tooth ring (158) on the outside. The second internal tooth ring (158) is fixed on the outer protrusion of the mounting slider (11). The second tooth ring (152) is connected to the outside of the first tooth disc (157). The first tooth disc (157) is installed on the oil assembly (16).

2. The machine tool for processing a high-stability composite wheel hub according to claim 1, characterized in that: Multiple first grooves (9) are opened at equal angles, and the number of multiple first grooves (9) corresponds to the number of second grooves (12).

3. The machine tool for processing a high-stability composite wheel hub according to claim 2, characterized in that: Both of the two rotating tubes (153) have threaded grooves on their outer sides, and the two rotating tubes (153) are slidably connected to the inner protrusions of the two adjusting sleeves (155) through the threaded grooves.

4. The machine tool for processing a high-stability composite wheel hub according to claim 3, characterized in that: The outer teeth of the two rotating tubes (153) are designed with one upper and one lower tooth, and the inner side of the second toothed ring (152) meshes with the lower outer tooth of one rotating tube (153).

5. The machine tool for processing a high-stability composite wheel hub according to claim 4, characterized in that: The lower ends of the two connecting posts (154) are respectively equipped with a drill bit (171) and a grinding head (172), and the diameter of the first toothed disc (157) is larger than the diameter of the second toothed ring (152).

6. The machine tool for processing a high-stability composite wheel hub according to claim 5, characterized in that: The oil assembly (16) includes a first oil tank (161), which is fixed at the bottom of the top groove of the mounting top (3). A first plug (162) is slidably connected to the inner cavity of the first oil tank (161). An electric push rod (163) is connected to the outer end of the first plug (162). The electric push rod (163) is fixed at the bottom of the top groove of the mounting top (3). The inner cavity of the first oil tank (161) is connected to multiple second oil tanks (164) through multiple hoses. The second oil tank (164) is fixed at the top of the left protrusion of the mounting slider (11). A second plug (165) is slidably connected to the inner cavity of the second oil tank (164) through a spring. A second post (166) is connected to the outer end protrusion of the second plug (165). The second post (166) is rotatably mounted on the top of the left protrusion of the mounting slider (11) through a bearing.

7. The machine tool for processing a high-stability composite hub according to claim 6, characterized in that: The first toothed disc (157) is installed on the outer side of the top of the second column (166).

8. The machine tool for processing a high-stability composite wheel hub according to claim 7, characterized in that: The No. 2 oil tank (164) and the No. 2 plug (165) are designed in an arc shape, and the center of the arc design of the No. 2 oil tank (164) and the No. 2 plug (165) corresponds to the center of the No. 2 column (166).

Images