Full-automatic tin feeding equipment for transformer production

Abstract

The present application relates to a kind of full-automatic tin equipment for transformer production, and it relates to transformer production technical field.The tin device main part is included, the inside upper portion of the tin device main part is equipped with grabbing arm, the spring sliding structure is arranged in the bottom clamp of the grabbing arm, the inside of the tin device main part is also connected with tin box, and the installation frame is connected on the both sides of the tin box.The present application, in the process of falling of the grabbing arm driving transformer, will drive the docking block to move downward, the docking block moves downward will make two groups of grid scrapers move, the oxidation film generated on the surface of tin liquid is moved to the front and rear sides of tin box by the movement of grid scraper, the rotating plate is also rotated in the movement process of grid scraper, the oxidation film on the front and rear sides is separated from tin liquid by the rotation of rotating plate and is made to enter into collection frame, reduces the condition that oxidation film is adsorbed in transformer pin, and by being provided with buffer block, rotating plate can be buffered, reduces the collision damage of rotating plate and grid scraper.

Description

Technical Field

[0001] This invention relates to the field of transformer manufacturing technology, specifically to a fully automatic tinning equipment for transformer manufacturing. Background Technology

[0002] A transformer is a static electrical device that works on the principle of electromagnetic induction. It can convert alternating current energy of one voltage and current into electrical energy of another voltage and current of the same frequency, realizing the core function of changing voltage without changing frequency. It is a key component for energy transmission and signal conversion in power systems and electronic equipment. A transformer is mainly composed of the transformer body and accessories. Transformers can be classified according to their uses into power transformers, distribution transformers and special transformers. Fully automatic tinning equipment is required in the transformer production process.

[0003] Existing fully automated tinning equipment typically uses a robotic arm to grip the transformer and immerse its pins in molten solder. During this process, the molten solder in the solder bath reacts with oxygen in the air, forming an oxide film on its surface. This oxide film adheres to the transformer pins during immersion, resulting in poor tinning. Furthermore, after the pins are removed from the molten solder, excessive solder may be absorbed, requiring a short period to allow the excess solder to drip back into the solder bath, thus prolonging the overall tinning time for the transformer. To address these issues, innovative designs based on existing methods are urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a fully automatic tinning device for transformer production, which solves the problem that in the aforementioned fully automatic tinning devices, the molten tin reacts with oxygen in the air during placement, forming an oxide film on the surface of the molten tin. This oxide film then adheres to the transformer pins during immersion, resulting in a poor tinning effect at the pins. The technical solution of this invention addresses the problem that existing solutions are too simplistic 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 fully automatic tinning device for transformer production, comprising a tinning device body, a gripping arm mounted on the upper inner side of the tinning device body, a spring sliding structure provided in the bottom clamp of the gripping arm, a tin box connected to the inner side of the tinning device body, mounting frames connected to both sides of the tin box, a lifting block slidably connected to the inner side of the mounting frames, a docking block rotatably connected to the lifting block, a pushing block slidably connected to the docking block, a first connecting rod hinged to the bottom of the lifting block, and a sliding block hinged to the bottom end of the first connecting rod, a hollow screw rotatably connected to the inner side of the sliding block, a connecting block threadedly connected to the hollow screw, and the connecting block slidably connected to the sliding block, a grid scraper connected to the side of the connecting block, a rotating plate rotatably connected to the inner side of the tin box, gears connected to the two ends of the rotating plate, and a toothed block connected to the connecting block;

[0006] A buffer assembly, the buffer assembly being disposed inside the mounting frame; a transmission assembly, the transmission assembly being disposed inside the mounting frame; and an adjustment assembly, the adjustment assembly being disposed inside the mounting frame.

[0007] Preferably, the buffer assembly has a buffer block slidably connected to the inner side of the mounting frame, the buffer block is connected to a buffer rod, and the buffer rod is slidably connected to the mounting frame. The buffer rod is connected to a buffer plate at one end on the outer side of the mounting frame. The buffer plate is provided with a first protrusion, and the first protrusion is slidably connected to the mounting frame. The lifting block is provided with a second protrusion on the side of the first protrusion.

[0008] Preferably, the transmission assembly has rotating rollers rotatably connected to both sides of the push block, a sliding rod is connected to the inner side of the mounting frame, and a protrusion is slidably connected to the sliding rod. A second connecting rod is hinged to the bottom of the protrusion, and an adjusting block is hinged to the bottom end of the second connecting rod. A partition is connected to the inner side of the mounting frame, and an adjusting screw is rotatably connected to the partition, and the adjusting screw is threadedly connected to the adjusting block.

[0009] Preferably, the adjustment assembly has a motor mounted on the outside of the mounting frame, the output end of the motor is connected to a bidirectional screw, the bidirectional screw is threadedly connected to an adjustment plate, and the adjustment plate is slidably connected to the mounting frame. The bidirectional screw is connected to the adjustment screw through a bevel gear set, and the adjustment plate is connected to a helical rod.

[0010] Preferably, the hollow screw has a semi-circular protrusion on its inner side, and a rotating groove is formed on the surface of the screw, and the semi-circular protrusion can be embedded into the rotating groove of the screw.

[0011] Preferably, the tin box is provided with a detachable collection frame on both the front and rear sides, and the top of both the front and rear sides of the tin box is sloping.

[0012] Preferably, the buffer block is connected to a first spring, and the other end of the first spring is connected to the inner wall of the mounting frame. The buffer rod passes through the hole formed in the center of the first spring. The buffer block is located on a sloped surface of the sliding block.

[0013] Preferably, a second spring is connected above the partition, and the top of the second spring is connected to the lifting block. A guide rod is also connected above the partition, and the guide rod passes through the central hole of the second spring and is slidably connected to the lifting block.

[0014] Preferably, each of the protrusions is provided with a curved protrusion, and there are two sets of protrusions, with the two sets of protrusions having different curved protrusion heights.

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

[0016] 1. In this invention, during the process of the gripping arm lowering the transformer, the docking block will move downwards. The downward movement of the docking block will cause two sets of grid scrapers to move. The movement of the grid scrapers will move the oxide film generated on the surface of the molten solder to the front and rear sides of the solder box. During the movement of the grid scrapers, the rotating plate will also rotate. The rotation of the rotating plate will separate the oxide film on the front and rear sides from the molten solder and let it enter the collection frame, reducing the situation where the oxide film is adsorbed on the transformer pins. In addition, the rotating plate can be buffered by the buffer block, reducing the occurrence of damage caused by collision between the rotating plate and the grid scraper.

[0017] 2. In this invention, the vertical movement of the docking block also drives the rotating roller to move vertically. During this vertical movement, the rotating roller, influenced by the protruding block, moves laterally. This lateral movement of the protruding block causes the transformer gripped by the robotic arm to sway slightly, allowing excess solder to drip more quickly into the solder box, improving the overall soldering efficiency of the transformer. 3. In this invention, starting the motor drives the bidirectional screw to rotate. The rotation of the bidirectional screw causes the protruding block to move laterally, thereby adjusting the lateral swaying amplitude of the pushing block. This allows for better shaking of transformers of different sizes, separating the pins from excess solder. Furthermore, the rotation of the bidirectional screw adjusts the position of the screw rod, thereby adjusting the movement distance of the grid scraper, allowing for better adjustment according to the transformer size. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the outer structure of the tin box of the present invention;

[0020] Figure 3 This is a schematic diagram of the inner structure of the mounting frame of the present invention;

[0021] Figure 4 For the present invention Figure 3 Enlarged structural diagram at point A;

[0022] Figure 5 For the present invention Figure 3 Enlarged structural diagram at point B;

[0023] Figure 6 This is a schematic diagram of the side structure of the mounting frame of the present invention;

[0024] Figure 7 For the present invention Figure 6 Enlarged structural diagram at point C;

[0025] Figure 8 For the present invention Figure 6 Enlarged structural diagram at point D;

[0026] Figure 9 This is a schematic diagram of the rear structure of the mounting frame of the present invention;

[0027] Figure 10 This is a schematic diagram of the top surface structure of the mounting frame of the present invention;

[0028] Figure 11 This is a side view of the transmission assembly of the present invention. In the figure: 1. Main body of the tinning device; 2. Gripping arm; 3. Tin box; 4. Lifting block; 5. Connecting block; 6. Pushing block; 7. First connecting rod; 8. Sliding block; 9. Hollow screw; 10. Connecting block; 11. Grid scraper; 12. Rotating plate; 13. Gear; 14. Tooth block; 15. Mounting frame; 16. Buffer assembly; 161. Buffer block; 162. Buffer rod; 163. Buffer plate; 17. Transmission assembly; 171. Rotating roller; 172. Protrusion block; 173. Second connecting rod; 174. Adjusting block; 175. Partition plate; 176. Adjusting screw; 18. Adjusting assembly; 181. Motor; 182. Bidirectional screw; 183. Adjusting plate; 184. Screw rod. Detailed Implementation

[0029] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description is provided in conjunction with the accompanying drawings and preferred embodiments, based on the specific implementation methods, structure, features, and effects of the present invention.

[0030] Please see Figure 1 - Figure 11This invention provides a technical solution: a fully automatic tinning device for transformer production, comprising a tinning device body 1, a gripping arm 2 mounted on the upper inner side of the tinning device body 1, a spring sliding structure provided at the bottom clamp of the gripping arm 2, a tin box 3 connected to the inner side of the tinning device body 1, mounting frames 15 connected to both sides of the tin box 3, a lifting block 4 slidably connected to the inner side of the mounting frame 15, a docking block 5 rotatably connected to the lifting block 4, a pushing block 6 slidably connected to the docking block 5, a first connecting rod 7 hinged to the bottom of the lifting block 4, and a sliding block 8 hinged to the bottom end of the first connecting rod 7, a hollow screw 9 rotatably connected to the inner side of the sliding block 8, a connecting block 10 threadedly connected to the hollow screw 9, and the connecting block 10 slidably connected to the sliding block 8, a grid scraper 11 connected to the side of the connecting block 10, and the tin box 3 containing... A rotating plate 12 is connected to the side. Gears 13 are connected to the two ends of the rotating plate 12. A toothed block 14 is connected to the connecting block 10. When the grabbing arm 2 drives the transformer to fall, it will drive the docking block 5 to move downward. The downward movement of the docking block 5 will cause the two sets of grid scrapers 11 to move. The movement of the grid scrapers 11 will drive the oxide film produced on the surface of the molten tin to move to the front and rear sides of the tin box 3. During the movement, the grid scrapers 11 will also gradually drive the rotating plate 12 to rotate. The rotation of the rotating plate 12 will separate the oxide film on the front and rear sides from the molten tin and let it enter the collection box, reducing the situation of oxide film adsorbing on the transformer pins. In addition, the buffer block 161 can buffer the horizontally moving rotating plate 12, reducing the occurrence of collision damage between the rotating plate 12 and the grid scraper 11.

[0031] The buffer assembly 16 is disposed inside the mounting frame 15; the transmission assembly 17 is disposed inside the mounting frame 15; and the adjustment assembly 18 is disposed inside the mounting frame 15.

[0032] In one embodiment of the present invention, the buffer assembly 16 has a buffer block 161 slidably connected to the inner side of the mounting frame 15, the buffer block 161 is connected to a buffer rod 162, and the buffer rod 162 is slidably connected to the mounting frame 15. The buffer rod 162 is connected to a buffer plate 163 at one end located outside the mounting frame 15. The buffer plate 163 is provided with a first protrusion, and the first protrusion is slidably connected to the mounting frame 15. The lifting block 4 is provided with a second protrusion on the side of the first protrusion.

[0033] In one embodiment of the present invention, the transmission assembly 17 has a rotating roller 171 rotatably connected to both sides of the push block 6, a sliding rod connected to the inner side of the mounting frame 15, and a protrusion 172 slidably connected to the sliding rod. A second connecting rod 173 is hinged to the bottom of the protrusion 172, and an adjusting block 174 is hinged to the bottom end of the second connecting rod 173. A partition 175 is connected to the inner side of the mounting frame 15, and an adjusting screw 176 is rotatably connected to the partition 175. The adjusting screw 176 is threadedly connected to the adjusting block 174. During the vertical movement of the docking block 5, the rotating roller 171 will also move vertically. During the vertical movement of the rotating roller 171, it will move laterally due to the influence of the protrusion 172. The lateral movement of the protrusion 172 will push the transformer grasped by the robotic arm to shake slightly, so that excess solder can drip into the solder box 3 more quickly, thereby improving the overall soldering efficiency of the transformer.

[0034] In one embodiment of the present invention, the adjustment assembly 18 has a motor 181 mounted on the outside of the mounting frame 15. The output end of the motor 181 is connected to a bidirectional screw 182. The bidirectional screw 182 is threadedly connected to an adjustment plate 183, and the adjustment plate 183 is slidably connected to the mounting frame 15. The bidirectional screw 182 is connected to the adjustment screw 176 through a bevel gear set. The adjustment plate 183 is connected to a spiral rod 184. By starting the motor 181, the bidirectional screw 182 can be driven to rotate. The rotation of the bidirectional screw 182 will drive the protrusion 172 to move laterally, thereby adjusting the lateral swaying amplitude of the push block 6. This can better shake transformers of different sizes to separate their pins from excess solder. In addition, the rotation of the bidirectional screw 182 will adjust the position of the spiral rod 184, thereby adjusting the movement distance of the grid scraper 11, which can be better adjusted according to the size of the transformer.

[0035] As one embodiment of the present invention, a semi-circular protrusion is provided on the inner side of the hollow screw 9, and a rotating groove is provided on the surface of the spiral rod 184. The semi-circular protrusion can be embedded into the rotating groove of the spiral rod 184. When the spiral rod 184 is inserted into the inner side of the hollow screw 9, the hollow screw 9 will rotate under the influence of the semi-circular protrusion.

[0036] As one embodiment of the present invention, the tin box 3 is provided with a detachable collection frame on both the front and rear sides, and the top of both the front and rear sides of the tin box 3 is sloping. By providing the collection frame, the tin oxide film can be collected, and the sloping shape prevents the oxide film from accumulating on the top of the tin box 3.

[0037] In one embodiment of the present invention, the buffer block 161 is connected to a first spring, and the other end of the first spring is connected to the inner wall of the mounting frame 15. The buffer rod 162 passes through the hole formed in the center of the first spring. By providing the first spring, the buffer block 161 can be pushed back to the initial position. The buffer block 161 is sloping on one side of the sliding block 8, and the sliding block 8 is sloping on one side of the buffer block 161. By setting both the buffer block 161 and the sliding block 8 in sloping shapes, the sliding block 8 can push the buffer block 161 to move during horizontal movement.

[0038] In one embodiment of the present invention, a second spring is connected above the partition 175, and the top of the second spring is connected to the lifting block 4. A guide rod is also connected above the partition 175, and the guide rod passes through the central hole of the second spring and is slidably connected to the lifting block 4. The second spring is provided to push the lifting block 4 back to the initial position, and the guide rod can limit the second spring to reduce the occurrence of deformation and misalignment of the second spring.

[0039] As one embodiment of the present invention, each of the protrusions 172 is provided with a curved protrusion, and there are two sets of protrusions 172. The two sets of protrusions 172 have different heights. By providing two sets of protrusions 172 with different heights, the transformer can be better pushed to shake, thereby reducing the occurrence of molten solder dripping onto the outside of the solder box 3.

[0040] Working principle: First, when tinning is required, the gripping arm 2 grips the transformer base and moves it above the tin box 3. Then, the gripping arm 2 is activated again to move downwards. During the downward movement, the gripping arm 2 will come into contact with the docking block 5 and push the docking block 5 downwards. The downward movement of the docking block 5 will drive the lifting block 4 downwards. Since the lifting block 4 is hinged to the first connecting rod 7, and the first connecting rod 7 is hinged to the sliding block 8, and the sliding block 8 is slidably connected to the mounting frame 15, the downward movement of the lifting block 4 will drive the sliding block 8 to move horizontally under the action of the first connecting rod 7. The horizontal movement of the sliding block 8 will drive the hollow screw 9 to move horizontally. The movement of the hollow screw 9 will drive the connecting block 10 to move. The movement of the connecting block 10 will drive the grid scraper 11 to move. During the movement of the hollow screw 9, the spiral rod 184 will be inserted into the inner side of the hollow screw 9. Since the inner side of the hollow screw 9 is provided with a semi-circular protrusion, the hollow screw 9 will be subjected to the semi-circular protrusion. The protrusion and the rotating groove of the spiral rod 184 affect the rotation. Since the hollow screw 9 is threadedly connected to the connecting block 10 and the connecting block 10 is slidably connected to the sliding block 8, the hollow screw 9 will drive the connecting block 10 to move. The two sets of grid scrapers 11 move in a mirror motion to push the oxide film on the surface of the molten tin to move. Under the influence of the grid scrapers 11, the oxide film is located on the front and rear sides of the tin box 3. During the movement of the connecting block 10, it will also drive the tooth block 14 to move. During the horizontal movement of the tooth block 14, it meshes with the gear 13, thereby driving the gear 13 to rotate. The rotation of the gear 13 drives the rotating plate 12 to rotate. The rotating plate 12 rotates and separates from the molten tin and drives the oxide film on the front and rear sides of the tin box 3 to move upward. During the rotation of the rotating plate 12, the oxide film will be affected by gravity and enter the collection box. The rotating plate 12 can process the oxide film accumulated on the front and rear sides of the tin box 3, thereby avoiding the situation of excessive accumulation of oxide film on the front and rear sides.

[0041] Secondly, during horizontal movement, the sliding block 8 contacts the buffer block 161 and pushes the buffer block 161 towards the inside of the mounting frame 15. When the sliding block 8 separates from the buffer block 161, the first spring will restore its deformation and push the buffer block 161 to fit against the side of the sliding block 8. The buffer block 161 provides a certain buffer for the sliding block 8, reducing the possibility of damage caused by the collision between the grid scraper 11 and the rotating plate 12. When the transformer pins are tinned and rise, the second spring will pull the lifting block 4 upward. The upward movement of the lifting block 4 drives the... The connecting block 5 moves upward, which drives the pushing block 6 to move upward. The pushing block 6 moves upward, which drives the rotating roller 171 to move upward. During the upward movement, the rotating roller 171 will contact the protruding block 172. Under the influence of the protruding block 172, the rotating roller 171 will reciprocate laterally. The reciprocating laterally movement of the protruding block 172 will drive the pushing block 6 to move laterally. The reciprocating laterally movement of the pushing block 6 will drive the movable clamp at the bottom of the gripping arm 2 to swing slightly back and forth, so that the excess molten solder adsorbed by the transformer pins falls into the solder box 3.

[0042] Finally, when tinning a larger transformer is required, motor 181 is started. Motor 181 drives the bidirectional screw 182 to rotate. Since the bidirectional screw 182 is connected to the adjusting screw 176 via a bevel gear set, its rotation drives the adjusting screw 176 to rotate. Because the adjusting screw 176 is threadedly connected to the adjusting block 174, and the adjusting block 174 is slidably connected to the partition plate 175, the rotation of the adjusting screw 176 causes the adjusting block 174 to move vertically. Furthermore, since the adjusting block 174 is hinged to the second connecting rod 173, and the second connecting rod 173 is hinged to the protruding block 172, and the protruding block 172 is slidably connected to the sliding rod, therefore… The vertical movement of the adjusting block 174 will cause the protruding block 172 to move laterally, thereby adjusting the position of the protruding block 172. After the position of the protruding block 172 is adjusted, the amplitude of the reciprocating lateral movement of the rotating roller 171 will increase, thus ensuring the shaking effect of the large-size transformer. Since the bidirectional screw 182 is threadedly connected to the adjusting plate 183 and the adjusting plate 183 is slidably connected to the mounting frame 15, the rotation of the bidirectional screw 182 will drive the adjusting plate 183 to move. The movement of the adjusting plate 183 will adjust the initial position of the screw rod 184, thereby increasing the distance that the hollow screw 9 drives the grid scraper 11 to move, thus avoiding the grid scraper 11 from colliding with the pins of the large-size transformer. The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A fully automatic tinning device for transformer production, comprising a tinning device body (1), characterized in that: A gripping arm (2) is installed on the upper inner side of the main body (1) of the tinning device. The gripping arm (2) has a spring sliding structure at its bottom clamp. A tin box (3) is also connected to the inner side of the main body (1). A mounting frame (15) is connected to both sides of the tin box (3). A lifting block (4) is slidably connected to the inner side of the mounting frame (15). A docking block (5) is rotatably connected to the lifting block (4). A pushing block (6) is slidably connected to the docking block (5). A first connecting rod (7) is hinged to the bottom of the lifting block (4). And the bottom end of the first connecting rod (7) is hinged to a sliding block (8), the inner side of the sliding block (8) is rotatably connected to a hollow screw (9), the hollow screw (9) is threadedly connected to a connecting block (10), and the connecting block (10) is slidably connected to the sliding block (8). The side of the connecting block (10) is connected to a grid scraper (11), the inner side of the tin box (3) is rotatably connected to a rotating plate (12), the two ends of the rotating plate (12) are connected to gears (13), and the connecting block (10) is connected to a toothed block (14). A buffer assembly (16) is disposed inside the mounting frame (15); A transmission assembly (17) is disposed inside the mounting frame (15); Adjustment component (18), the adjustment component (18) is disposed inside the mounting frame (15); The buffer assembly (16) has a buffer block (161) slidably connected to the inner side of the mounting frame (15). The buffer block (161) is connected to a buffer rod (162), and the buffer rod (162) is slidably connected to the mounting frame (15). The buffer rod (162) is connected to a buffer plate (163) at one end outside the mounting frame (15). The buffer plate (163) is provided with a first protrusion, and the first protrusion is slidably connected to the mounting frame (15). The lifting block (4) is provided with a second protrusion on the side of the first protrusion. The transmission assembly (17) has a rotating roller (171) rotatably connected to both sides of the push block (6). A sliding rod is connected to the inner side of the mounting frame (15), and a protrusion (172) is slidably connected to the sliding rod. A second connecting rod (173) is hinged to the bottom of the protrusion (172), and an adjusting block (174) is hinged to the bottom end of the second connecting rod (173). A partition (175) is connected to the inner side of the mounting frame (15), and an adjusting screw (176) is rotatably connected to the partition (175). The adjusting screw (176) is threadedly connected to the adjusting block (174). The adjustment assembly (18) has a motor (181) installed on the outside of the mounting frame (15). The output end of the motor (181) is connected to a bidirectional screw (182). The bidirectional screw (182) is threadedly connected to an adjustment plate (183), and the adjustment plate (183) is slidably connected to the mounting frame (15). The bidirectional screw (182) is connected to the adjustment screw (176) through a bevel gear set. The adjustment plate (183) is connected to a spiral rod (184). The hollow screw (9) has a semi-circular protrusion on its inner side, and the spiral rod (184) has a rotating groove on its surface. The semi-circular protrusion can be embedded into the rotating groove of the spiral rod (184).

2. The fully automatic tinning equipment for transformer production according to claim 1, characterized in that: The tin box (3) is equipped with detachable collection frames on both the front and rear sides, and the top of both the front and rear sides of the tin box (3) is sloping.

3. The fully automatic tinning equipment for transformer production according to claim 2, characterized in that: The buffer block (161) is connected to a first spring, and the other end of the first spring is connected to the inner wall of the mounting frame (15). The buffer rod (162) passes through the hole formed in the center of the first spring. The buffer block (161) is located on the inclined surface of the sliding block (8), and the sliding block (8) is located on the inclined surface of the buffer block (161).

4. The fully automatic tinning equipment for transformer production according to claim 3, characterized in that: A second spring is connected above the partition (175), and the top of the second spring is connected to the lifting block (4). A guide rod is also connected above the partition (175), and the guide rod passes through the central hole of the second spring and is slidably connected to the lifting block (4).

5. The fully automatic tinning equipment for transformer production according to claim 3, characterized in that: The protrusions (172) are all provided with curved protrusions, and there are two sets of protrusions (172), and the height of the curved protrusions of the two sets of protrusions (172) is different.

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