A metal arc tube inner cavity grinding device

Abstract

The present invention belongs to the technical field of pipeline inner cavity grinding, and discloses a metal arc-shaped pipe inner cavity grinding device, including a pipeline, an annular sleeve plate 1 is installed on one side of the outer wall of the pipeline, an annular sleeve plate 2 is installed on one end of the pipeline close to the annular sleeve plate 1, compression grooves are opened on three sides of the outer wall of the annular sleeve plate 1, and a limiting groove 1 is opened on both sides of the inner part of the compression groove on one side. In the present invention, when moving forward and encountering an arc bend, the roller will press down to make the guide rod 1 drive the hinge seat 1 to slide in the compression groove, and at the same time make the spring 1 be squeezed, so that the roller can always contact the inner wall of the pipeline to stabilize the grinding head, so as to prevent the worker from shaking the pipeline when holding the pipeline for a long time, which may cause the grinding head to deviate and cause uneven grinding of the pipeline inner cavity, and at the same time avoid the safety hazards caused by hand holding.

Description

Technical Field

[0001] The invention belongs to the technical field of pipeline inner cavity grinding, and in particular relates to a metal arc-shaped pipe inner cavity grinding device. Background Art

[0002] The Metal Curved Pipe Grinding Device is a mechanical device specifically designed for grinding and treating the inner surface of metal pipes, especially curved pipes. Its primary function is to clean the inner cavity of metal pipes, remove oxide layers and impurities, or provide surface smoothing to ensure the inner wall of the pipe meets certain smoothness and precision requirements.

[0003] In the common metal arc tube inner cavity grinding device, a person needs to hold the engraving grinder with one hand and hold the pipeline connected to the grinding head with the other hand to control the angle of the grinding head. The operation is relatively cumbersome, and when holding the pipeline connected to the grinding head with the hand, it will inevitably cause the grinding head to be unstable and thus reduce the grinding effect. At the same time, there are certain safety risks when holding the connecting grinding head with the hand. Secondly, after the metal arc tube is polished, the dust on the inner wall needs to be cleaned. When cleaning the metal arc tube, the arc-shaped pipeline is not convenient for cleaning inside the pipeline, resulting in the dust from grinding affecting the use of the metal arc tube. Summary of the Invention

[0004] In order to solve the problems raised in the above background technology that holding the pipeline to control the angle of the grinding head and adjusting the angle for a long time will inevitably lead to instability of the grinding head and reduce the grinding effect, and there are certain safety risks in holding the connected grinding head with hands, and the problem that the metal arc pipe is inconvenient to clean inside the pipe due to its arc shape, the present invention provides a metal arc pipe inner cavity grinding device.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: A metal arc tube inner cavity grinding device comprises a pipeline, an annular sleeve plate 1 is installed on one side of the outer wall of the pipeline, an annular sleeve plate 2 is installed on one end of the pipeline close to the annular sleeve plate 1, compression grooves are provided on three sides of the outer wall of the annular sleeve plate 1, and a limiting groove 1 is provided on both sides of the inner wall of the compression groove on one side, a spring 1 is installed on one side of the inner wall of the compression groove, an end of the spring 1 away from the compression groove is fixedly connected to a hinge seat 1, and the hinge seat 1 slides in the compression groove, both sides of the hinge seat 1 are fixedly connected to a limiting plate 1, and the limiting plate 1 slides in the limiting groove 1, a guide rod 1 is rotatably connected to the top of the hinge seat 1, an end of the guide rod 1 away from the hinge seat 1 passes through and is rotatably connected to a connecting shaft, a roller is fixedly connected to the middle part of the outer wall of the connecting shaft, and guide rods 2 are rotatably connected to both sides of the outer wall of the connecting shaft, three hinge seats 2 are fixedly connected to the outer wall of the annular sleeve plate 2, and the side of the guide rod 2 away from the connecting shaft is rotatably connected to the hinge seat 2.

[0006] Preferably, the outer walls of the three annular sleeve plates are provided with output grooves on both sides of the compression groove, the two ends of the connecting shaft are rotatably connected to the output rod 1, and the output rod 1 slides in the output groove, and the output rod 1 is rotatably connected to the output rod 2 at one end away from the connecting shaft, an annular cleaning plate 1 is fixedly connected to the edge of one side of the outer wall of the annular sleeve plate, three annular cleaning plates 2 are penetrated and slidably connected to the inside of the annular cleaning plate 1, two grooves 1 are provided on the side of the annular cleaning plate 2 close to the output rod 2, and the end of the output rod 2 away from the output rod 1 is rotatably connected to the inside of the groove 1, a spring groove is provided on the top of the groove 1, a spring 2 is installed inside the spring groove, a scraper is fixedly connected to the side of the spring 2 away from the spring groove, and the scraper slides in the spring groove.

[0007] Preferably, an output rod three is fixedly connected to one side of the outer wall of the guide rod two, three annular baffles one are fixedly connected to the edge of one side of the outer wall of the annular sleeve two, annular baffle one is passed through and slidably connected to the inside of the annular baffle one, a groove two is provided on the side of the annular baffle two close to the output rod three, and the output rod three is rotatably connected to the inside of the groove two on the side away from the guide rod two.

[0008] Preferably, the outer wall of the annular sleeve plate 2 is fixedly connected with a collection box between the hinge seat 2 and the annular baffle 1, and a collection groove is penetrated and opened on one side of the annular baffle 1, and the collection groove cooperates with the collection box.

[0009] Preferably, two limiting grooves are provided on both sides of the inner cavity of the annular cleaning plate 2, and the two sides of the scraper are fixedly connected to the limiting plate 2, and the limiting plate 2 slides in the limiting groove 2.

[0010] Preferably, a second connection end is installed at one end of the pipeline, and an output pipeline is installed at an end of the second connection end away from the pipeline.

[0011] Preferably, a connection end 1 is installed at one end of the output pipeline away from the connection end 2, and a pneumatic grinder is installed at one end of the connection end 1 away from the output pipeline.

[0012] Preferably, an air connection end is installed at one end of the pneumatic grinder away from the connection end, and the air pump is connected via the air connection end.

[0013] Preferably, the end of the pipeline away from the second connecting end passes through the second annular sleeve plate and is installed with a threaded rod, and the outer wall of the threaded rod is threadedly connected to a grinding head.

[0014] Preferably, outer walls of the three rollers are all covered with rubber pads, which increase friction and make the grinding head work more stably.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention prevents the worker from shaking the pipeline held by the worker due to holding the pipeline for a long time by arranging the cooperation of the guide rod and the hinge seat. This is very likely to cause the grinding head to deviate, resulting in uneven grinding of the pipeline lumen. When moving forward and encountering an arc bend, the roller will press down to cause the guide rod to drive the hinge seat to slide in the compression groove, and at the same time cause the spring to be squeezed, so that the roller can always contact the inner wall of the pipeline to stabilize the grinding head. In this way, the worker can be prevented from shaking the pipeline held by the worker due to holding the pipeline for a long time, which may cause the grinding head to deviate, resulting in uneven grinding of the pipeline lumen, and at the same time avoid the safety hazards caused by holding the pipeline.

[0017] The present invention prevents the dust left after grinding in the metal arc tube from affecting the subsequent use of the metal arc tube by arranging the cooperation of the output rod 1 and the annular cleaning plate 2. When the roller enters the inner cavity of the metal arc tube, it will squeeze the roller to drive the output rod 1 to slide in the output groove, and at the same time drive the output rod 1 to move forward. The movement of the output rod 1 causes the annular cleaning plate 2 to move upward. At the same time, the output rod 1 rotates in the groove 1. During the upward movement of the annular cleaning plate 2, the scraper is driven to move upward so that the scraper contacts the inner wall of the metal arc tube. The spring 2 can keep the scraper in the contact state at all times. When the grinding head is pulled out after grinding is completed, the dust left after grinding in the metal arc tube is brought out by the scraper, thereby preventing the dust left after grinding in the metal arc tube from affecting the subsequent use of the metal arc tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0019] Figure 2 Schematic diagram of the threaded rod and grinding head of the present invention;

[0020] Figure 3 Schematic diagram of annular sleeve plate 1 and annular sleeve plate 2 of the present invention;

[0021] Figure 4 This is a cross-sectional view of the annular sleeve of the present invention;

[0022] Figure 5 A cross-sectional view of an annular cleaning plate of the present invention;

[0023] Figure 6 For the present invention Figure 5 Enlarged view of point A in the middle;

[0024] Figure 7 A side cross-sectional view of an annular cleaning plate 1 and an annular cleaning plate 2 of the present invention;

[0025] Figure 8 A cross-sectional view of an annular baffle according to the present invention;

[0026] Figure 9 For the present invention Figure 8 Enlarged view of point B in the middle.

[0027] In the figure: 1, pipeline; 2, annular sleeve plate 1; 3, annular sleeve plate 2; 4, compression groove; 5, limit groove 1; 6, spring 1; 7, hinge seat 1; 8, limit plate 1; 9, guide rod 1; 10, connecting shaft; 11, roller; 12, guide rod 2; 13, hinge seat 2; 14, output groove; 15, output rod 1; 16, output rod 2; 17, annular cleaning plate 1; 18, annular cleaning plate 2; 19, groove 1; 20. Spring slot; 21. Spring 2; 22. Scraper; 23. Limit slot 2; 24. Limit plate 2; 25. Output rod 3; 26. Annular baffle 1; 27. Annular baffle 2; 28. Groove 2; 29. Collection tank; 30. Collection box; 31. Pneumatic grinder; 32. Connection end 1; 33. Output pipeline; 34. Connection end 2; 35. Threaded rod; 36. Grinding head; 37. Air connection end; 38. Rubber pad. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] like Figures 1 to 9 As shown, the present invention provides a metal arc tube inner cavity grinding device, including a pipeline 1, an annular sleeve 2 is installed on one side of the outer wall of the pipeline 1, an annular sleeve 3 is installed on the end of the pipeline 1 close to the annular sleeve 2, compression grooves 4 are opened on three sides of the outer wall of the annular sleeve 2, and limiting grooves 5 are opened on both sides of the inner wall of one side of the compression groove 4. A spring 6 is installed on one side of the inner wall of the compression groove 4, and the end of the spring 6 away from the compression groove 4 is fixedly connected to a hinge seat 7, and the hinge seat 7 slides in the compression groove 4. The hinge seat 7 The two sides of the annular sleeve 2 are fixedly connected to the limit plate 8, and the limit plate 8 slides in the limit groove 5. The top of the articulated seat 7 is rotatably connected to a guide rod 9. The end of the guide rod 9 away from the articulated seat 7 passes through and is rotatably connected to a connecting shaft 10. The middle part of the outer wall of the connecting shaft 10 is fixedly connected to a roller 11. The two sides of the outer wall of the connecting shaft 10 are rotatably connected to guide rods 2 12. The outer wall of the annular sleeve 2 3 is fixedly connected to three articulated seats 2 13. The side of the guide rod 2 12 away from the connecting shaft 10 is rotatably connected to the articulated seat 2 13.

[0030] The above scheme is adopted: when the annular sleeve 1 2 and the annular sleeve 2 3 are completely entered into the pipeline, the roller 11 and the rubber pad 38 will contact the inner wall of the pipeline to fix the grinding head 36. When moving forward and encountering an arc bend, the roller 11 will press down to make the guide rod 19 drive the hinge seat 17 to slide in the compression groove 4, and at the same time make the spring 16 be squeezed. The function is to make the roller 11 always contact the inner wall of the pipeline to stabilize the grinding head 36. In this way, it can prevent the staff from shaking the pipeline 1 due to holding the pipeline for a long time, which may cause the grinding head 36 to deviate, resulting in uneven grinding of the pipeline cavity, and at the same time avoid the safety hazards caused by holding the pipeline.

[0031] like Figures 1 to 9 As shown, the outer walls of the three annular sleeves 2 are located on both sides of the compression groove 4 and are provided with output grooves 14. The two ends of the connecting shaft 10 are rotatably connected to the output rod 15, and the output rod 15 slides in the output groove 14. The output rod 15 is rotatably connected to the output rod 2 16 at one end away from the connecting shaft 10. An annular cleaning plate 17 is fixedly connected to the edge of one side of the outer wall of the annular sleeve 2. Three annular cleaning plates 2 18 are penetrated and slidably connected to the inside of the annular cleaning plate 17. Two grooves 19 are provided on the side of the annular cleaning plate 2 18 close to the output rod 2 16. The end of the output rod 2 16 away from the output rod 15 is rotatably connected to the inside of the groove 19. A spring groove 20 is provided at the top of the groove 19. A spring 21 is installed inside the spring groove 20. A scraper 22 is fixedly connected to the side of the spring 21 away from the spring groove 20, and the scraper 22 slides in the spring groove 20.

[0032] The above solution is adopted: when the roller 11 enters the inner cavity of the metal arc tube, it will drive the output rod 15 to slide in the output groove 14 through squeezing, and at the same time drive the output rod 15 to move forward. The movement of the output rod 15 causes the annular cleaning plate 2 18 to move upward, and at the same time the output rod 15 rotates in the groove 19. During the upward movement of the annular cleaning plate 2 18, the scraper 22 will be driven to move upward so that the scraper 22 contacts the inner wall of the metal arc tube. The spring 2 21 can keep the scraper 22 in a state of contact at all times. After grinding is completed, the grinding head 36 is pulled out so that the dust ground in the metal arc tube is taken out through the scraper 22, thereby preventing the dust left in the metal arc tube from affecting the subsequent use of the metal arc tube.

[0033] like Figures 1 to 9As shown, an output rod 3 25 is fixedly connected to one side of the outer wall of the guide rod 2 12 on one side, and three annular baffles 1 26 are fixedly connected to the edge of one side of the outer wall of the annular sleeve 2 3. An annular baffle 27 is inserted through and slidably connected to the inside of the annular baffle 1 26 on one side. A groove 28 is formed on the side of the annular baffle 2 27 close to the output rod 3 25. The side of the output rod 3 25 away from the guide rod 2 12 is rotatably connected to the inside of the groove 2 28.

[0034] The outer wall of the annular sleeve 3 is located between the hinge seat 2 13 and the annular baffle 1 26 and is fixedly connected to a collection box 30. A collection groove 29 is penetrated and opened on one side of the annular baffle 1 26, and the collection groove 29 cooperates with the collection box 30.

[0035] With the above solution, when the roller 11 enters the inner cavity of the metal arc tube and squeezes to cause the roller 11 to descend, the guide rod 2 12 will also descend. When the guide rod 2 12 descends, the output rod 3 25 can be moved upward. The upward force of the output rod 3 25 drives the annular baffle 2 27 to move upward, so that the annular baffle 2 27 can prevent the dust generated during grinding from affecting the components connecting the annular sleeve 1 2 and the outer wall of the annular sleeve 2 3.

[0036] The dust blocked by the annular baffle 1 26 and the annular baffle 2 27 will enter the collection box 30 through the collection groove 29 for collection.

[0037] like Figures 1 to 9 As shown, two limiting grooves 23 are provided on both sides of the inner cavity of the annular cleaning plate 18 , and two limiting plates 24 are fixedly connected to both sides of the scraper 22 , and the limiting plates 24 slide in the limiting grooves 23 .

[0038] With the above solution, the cooperation between the second limiting groove 23 and the second limiting plate 24 can prevent the scraper 22 from being separated from the second annular cleaning plate 18 .

[0039] like Figures 1 to 9 As shown, one end of the pipeline 1 is equipped with a connecting end 2 34, the end of the connecting end 2 34 away from the pipeline 1 is equipped with an output pipeline 33, the end of the output pipeline 33 away from the connecting end 2 34 is equipped with a connecting end 1 32, the end of the connecting end 1 32 away from the output pipeline 33 is equipped with a pneumatic grinder 31, the end of the pneumatic grinder 31 away from the connecting end 1 32 is equipped with an air connecting end 37, and the air pump is connected through the air connecting end 37. The end of the pipeline 1 away from the connecting end 2 34 passes through the annular sleeve 2 3 and is equipped with a threaded rod 35. The outer wall of the threaded rod 35 is threadedly connected to the grinding head 36, and the outer walls of the three rollers 11 are all covered with rubber pads 38. The rubber pads 38 increase the friction so that the grinding head 36 can work stably.

[0040] Adopt the above solution: first connect the air connection end 37 to the air pump and then start the pneumatic grinder 31 to drive the grinding head 36 to rotate through the output pipeline 33 and pipeline 1 to grind the inner cavity of the pipeline.

[0041] The working principle and use process of the present invention:

[0042] When the tool 36 is in working order, the tool 36 is first placed in the pipe to be polished, and then the pneumatic grinder 31 is turned on to drive the threaded rod 35 to rotate the grinding head 36 to grind the inner cavity of the pipe. Then, the grinding head 36 is directed forward by the air connecting end 37. When the annular sleeve 2 and the annular sleeve 2 3 are completely in the pipe, the roller 11 and the rubber pad 38 will contact the inner wall of the pipe to fix the grinding head 36. When the tool 36 is in working order, the roller 11 will press down to make the guide rod 19 drive the hinge seat 17 to slide in the compression groove 4, and at the same time make the spring 16 squeeze, so that the roller 11 can always contact the inner wall of the pipe to stabilize the grinding head 36. This can prevent the tool 36 from shaking when holding the pipe for a long time, which is very likely to cause the grinding head 36 to deviate and cause uneven grinding of the inner cavity of the pipe. At the same time, it can avoid the safety hazards caused by holding the tool.

[0043] When the roller 11 enters the inner cavity of the metal arc tube, it will squeeze the roller 11 to drive the output rod 15 to slide in the output groove 14, and at the same time drive the output rod 15 to move forward. The movement of the output rod 15 causes the annular cleaning plate 2 18 to move upward. At the same time, the output rod 15 rotates in the groove 19. During the upward movement of the annular cleaning plate 2 18, the scraper 22 will be driven to move upward so that the scraper 22 contacts the inner wall of the metal arc tube. The spring 21 can keep the scraper 22 in a state of contact. After the grinding is completed, the grinding head 36 is pulled out so that the dust in the metal arc tube is taken out by the scraper 22, so as to prevent the dust left in the metal arc tube from affecting the subsequent use of the metal arc tube.

[0044] When the roller 11 enters the inner cavity of the metal arc tube and squeezes to cause the roller 11 to descend, the guide rod 2 12 will also descend. When the guide rod 2 12 descends, the output rod 3 25 can move upward. The upward force of the output rod 3 25 drives the annular baffle 2 27 to move upward, so that the inner wall of the metal arc tube of the annular baffle 2 27 can be prevented from the dust generated during grinding from affecting the components connected to the outer wall of the annular sleeve plate 1 2 and the annular sleeve plate 2 3. At the same time, the dust blocked by the annular baffle 1 26 and the annular baffle 2 27 will enter the collection box 30 through the collection groove 29 for collection.

[0045] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0046] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A metal arc tube inner cavity grinding device, comprising a pipeline (1) characterized by: An annular sleeve plate 1 (2) is installed on one side of the outer wall of the pipeline (1), and an annular sleeve plate 2 (3) is installed on one end of the pipeline (1) close to the annular sleeve plate 1 (2). Compression grooves (4) are provided on three sides of the outer wall of the annular sleeve plate 1 (2), and limiting grooves 1 (5) are provided on both sides of the inner wall of the compression groove (4). A spring 1 (6) is installed on one side of the inner wall of the compression groove (4), and an end of the spring 1 (6) away from the compression groove (4) is fixedly connected to a hinge seat 1 (7), and the hinge seat 1 (7) slides in the compression groove (4), and both sides of the hinge seat 1 (7) are fixedly connected to the limiting plate 1 ( 8), and the limiting plate 1 (8) slides in the limiting groove 1 (5), the top of the hinge seat 1 (7) is rotatably connected to the guide rod 1 (9), the end of the guide rod 1 (9) away from the hinge seat 1 (7) passes through and is rotatably connected to the connecting shaft (10), the middle part of the outer wall of the connecting shaft (10) is fixedly connected to the roller (11), the two sides of the outer wall of the connecting shaft (10) are rotatably connected to the guide rod 2 (12), the outer wall of the annular sleeve plate 2 (3) is fixedly connected to three hinge seats 2 (13), and the side of the guide rod 2 (12) away from the connecting shaft (10) is rotatably connected to the hinge seat 2 (13); The outer walls of the three annular sleeves (2) are provided with output grooves (14) on both sides of the compression groove (4), and the two ends of the connecting shaft (10) are rotatably connected to the output rods (15), and the output rods (15) slide in the output grooves (14), and the output rods (15) are rotatably connected to the output rods (16) at one end away from the connecting shaft (10). The outer wall of the annular sleeve (2) is fixedly connected to the edge of an annular cleaning plate (17), and the interior of the annular cleaning plate (17) is penetrated and slidably connected to three annular cleaning plates. A second cleaning plate (18), wherein the annular cleaning plate (18) is provided with two first grooves (19) on one side close to the second output rod (16), and the end of the second output rod (16) away from the first output rod (15) is rotatably connected to the inside of the first groove (19), and a spring groove (20) is provided on the top of the first groove (19), and a second spring (21) is installed inside the spring groove (20), and a scraper (22) is fixedly connected to the side of the second spring (21) away from the spring groove (20), and the scraper (22) slides in the spring groove (20); An output rod 3 (25) is fixedly connected to one side of the outer wall of the guide rod 2 (12), and three annular baffles 1 (26) are fixedly connected to the edge of one side of the outer wall of the annular sleeve plate 2 (3). An annular baffle 2 (27) is passed through and slidably connected to the inside of the annular baffle 1 (26) on one side. A groove 2 (28) is provided on the side of the annular baffle 2 (27) close to the output rod 3 (25), and the side of the output rod 3 (25) away from the guide rod 2 (12) is rotatably connected to the inside of the groove 2 (28); The outer wall of the annular sleeve plate 2 (3) is fixedly connected with a collection box (30) between the hinge seat 2 (13) and the annular baffle plate 1 (26), and a collection groove (29) is penetrated and opened on one side of the annular baffle plate 1 (26), and the collection groove (29) is matched with the collection box (30).

2. The metal arc tube inner cavity grinding device according to claim 1, characterized in that: The inner cavity of the annular cleaning plate (18) is provided with two limiting grooves (23), and the two sides of the scraper (22) are fixedly connected to the limiting plate (24), and the limiting plate (24) slides in the limiting groove (23).

3. The metal arc tube inner cavity grinding device according to claim 1, characterized in that: One end of the pipeline (1) is provided with a second connection end (34), and an output pipeline (33) is provided at the end of the second connection end (34) away from the pipeline (1).

4. The metal arc tube inner cavity grinding device according to claim 3, characterized in that: The output pipeline (33) is provided with a connection end 1 (32) at one end thereof away from the connection end 2 (34), and the connection end 1 (32) is provided with a pneumatic grinder (31) at one end thereof away from the output pipeline (33).

5. The metal arc tube inner cavity grinding device according to claim 4, characterized in that: An air connection end (37) is installed at one end of the pneumatic engraving and grinding machine (31) away from the connection end (32), and is connected to an air pump via the air connection end (37).

6. The metal arc tube inner cavity grinding device according to claim 1, characterized in that: One end of the pipeline (1) away from the second connection end (34) passes through the second annular sleeve plate (3) and is installed with a threaded rod (35), and the outer wall of the threaded rod (35) is threadedly connected to a grinding head (36).

7. The metal arc tube inner cavity grinding device according to claim 1, characterized in that: The outer walls of the three rollers (11) are all sleeved with rubber pads (38), and the rubber pads (38) increase the friction force so that the grinding head (36) works stably.

Images