A transportation skid for pressure operation equipment

Abstract

The present application relates to a transportation skid for pressure operation equipment, belonging to the field of transportation technology for pressure operation equipment. It includes a base, a support frame is arranged on the base, a connecting piece is rotatably arranged on the support frame, the connecting piece is used to connect with the pressure operation equipment, and a positioning piece is further included, and the positioning piece is used to fix the connecting piece. The present application has the effect of facilitating the transportation of the pressure operation equipment.

Description

Technical Field

[0001] The present application relates to the field of transportation technology for pressure - operated workover equipment, and more particularly to a transportation skid for pressure - operated workover equipment. Background Art

[0002] Currently, pressure - operated workover is one of the most applicable technologies in the oil and gas exploration and development field, which can provide solutions to most requirements and problems. Among them, pressure - operated workover equipment is a kind of equipment that can effectively implement the operation process of drilling and workover without the need for well killing or blowout prevention operations. During the operation process, it can avoid the pollution of the production formation by well - killing fluid, and maximize the protection of the production potential and output of oil wells. Since pressure - operated workover often requires changing the construction site, when relocating pressure - operated workover equipment, some transportation devices are often needed to transport and use the pressure - operated workover equipment.

[0003] Regarding the above - mentioned related technologies, the inventor believes that due to the large volume of common pressure - operated workover equipment and the inconvenience of frequent disassembly, it is rather troublesome during transportation and relocation, greatly reducing the work efficiency of staff and increasing transportation costs. Summary of the Invention

[0004] In order to facilitate the transportation of pressure - operated workover equipment, the present application provides a transportation skid for pressure - operated workover equipment.

[0005] The transportation skid for pressure - operated workover equipment provided by the present application adopts the following technical solutions:

[0006] A transportation skid for pressure - operated workover equipment includes a base, a support frame is arranged on the base, a connecting piece is rotatably arranged on the support frame, the connecting piece is used for connecting with the pressure - operated workover equipment, and a positioning piece is further included, and the positioning piece is used for fixing the connecting piece.

[0007] By adopting the above - mentioned technical solutions, when it is necessary to transport the pressure - operated workover equipment, the positioning piece is used to fix the connecting piece, so that the connecting piece cannot rotate. Then, the pressure - operated workover equipment is hoisted and installed and connected with the connecting piece. After the installation is completed, the positioning piece is removed and no longer fixes the connecting piece. Then, the pressure - operated workover equipment is slowly rotated towards the base by using a crane, thereby driving the connecting piece to rotate on the support frame until the pressure - operated workover equipment is stably placed on the base. In this way, the pressure - operated workover equipment can be integrally carried and transported, thus saving the process of disassembling the pressure - operated workover equipment before transportation, greatly saving time and transportation costs.

[0008] Optionally, the connecting member includes a first flange, a connecting structure and a rotating structure, the rotating structure is rotatably arranged on a support frame, and the connecting structure is fixedly connected between the first flange and the rotating structure; the support frame includes a first support frame and a second support frame, and the rotating structure is rotatably arranged between the first support frame and the second support frame.

[0009] By adopting the above technical solution, the first flange is rotated to a position where it can be connected to the vertical pressure working equipment through the rotating structure, and fixed by means of fixing parts. Then, the first flange and the flange at the bottom of the pressure working equipment are fixedly connected by studs and nuts. The fixing parts are removed, and then the pressure working equipment is hoisted by a crane and slowly rotated toward the base through the rotating structure, thereby facilitating the rotation of the pressure working equipment until it is stably placed on the base.

[0010] Optionally, a limiting structure is further included, wherein the limiting structure is used to limit the rotating structure between the first supporting frame and the second supporting frame.

[0011] By adopting the above technical solution, the rotating structure is limited between the first support frame and the second support frame by using a limiting structure, which to a certain extent avoids the situation where the first flange plate moves left and right through the rotating structure when rotating, thereby improving the stability during rotation.

[0012] Optionally, the connecting structure includes a connecting cylinder, and the rotating structure includes a rotating cylinder. The connecting cylinder and the rotating cylinder are both hollow, and annular grooves are circumferentially opened at both ends of the rotating cylinder. Sleeves are sleeved in the annular grooves at both ends, one of the sleeves is arranged on a first support frame, and the other sleeve is arranged on a second support frame. The connecting cylinder is arranged on the rotating cylinder, and the first flange is connected to the rotating cylinder through the connecting cylinder.

[0013] By adopting the above technical solution, the first flange can be smoothly rotated between the first support frame and the second support frame by utilizing the rotational cooperation between the rotating cylinder and the sleeves at both ends, thereby improving the stability of the pressure-operated equipment during rotation.

[0014] Optionally, the positioning member includes a pin shaft, a first through hole is formed on the sleeve, and a second through hole is formed on the rotating cylinder. When the disk surface of the first flange away from the side of the connecting cylinder rotates to a position away from the base, the first through hole and the second through hole are opposite to each other, and the pin shaft fixes the sleeve and the rotating cylinder after passing through the first through hole and the second through hole, and a lifting ring is provided on the pin shaft.

[0015] By adopting the above technical solution, the disk surface of the first flange away from the connecting tube is rotated to a position away from the base, so that the first through hole and the second through hole are opposite to each other, and then the pin shaft is passed through the first through hole and the second through hole, so that the rotating tube and the sleeve cannot rotate relative to each other, thereby improving the stability when the first flange is installed and connected to the pressure-operated equipment, and to a certain extent avoiding the rotation of the rotating tube during installation; when the staff needs to take out the pin shaft, they can pull the lifting ring to extract the pin shaft from the first through hole and the second through hole, thereby facilitating the staff to plug and unplug the pin shaft, thereby improving the work efficiency of the staff.

[0016] Optionally, limiting grooves are provided on the sleeves at both ends, and the limiting structure includes a limiting block, which is rotatably arranged in the limiting groove. When the limiting block is in contact with the end of the limiting groove away from the base, the first through hole and the second through hole are opposite to each other, and when the limiting block is in contact with the end of the limiting groove close to the base, the first through hole and the second through hole are staggered.

[0017] By adopting the above technical scheme, the rotating cylinder is limited in the sleeves at both ends by using the limiting grooves at both ends and the limiting blocks at both ends of the rotating cylinder, so that the rotating cylinder cannot move left and right when rotating; the limiting grooves are used to limit the rotation angle of the limiting blocks, so that when the limiting blocks are rotated to fit with the end of the limiting groove away from the base, the first through hole and the second through hole are directly opposite to each other, so that it is convenient to insert the pin shaft into the first through hole and the second through hole to fix the sleeve and the rotating cylinder.

[0018] Optionally, a fixing piece is also provided on the base, and the fixing piece is used to fix the pressure-operating equipment on the base.

[0019] By adopting the above technical solution, when the staff needs to repair the pressurized working equipment, they can fix the pressurized working equipment on the base through the fixing parts, and then perform maintenance and repair operations on the pressurized working equipment on the base, thereby facilitating the debugging and repair of the pressurized working equipment.

[0020] Optionally, the fixing member includes a second flange, and the second flange is arranged on the base.

[0021] By adopting the above technical solution, when the pressurized working equipment needs to be repaired, the flange at the bottom of the pressurized working equipment is connected to the second flange, and then the pressurized working equipment is stably installed on the base, thereby improving the stability and safety during maintenance and repair.

[0022] Optionally, the second flange is a threaded flange.

[0023] By adopting the above technical solutions, compared with other flange plates, the studded flange plate has the advantages of flexible and simple installation and convenient operation and maintenance, and can adapt to various complex working conditions; the bolt holes on the studded flange plate are threaded holes. After the stud bolt passes through the flange plate at the bottom of the pressure operation equipment and is thread-fitted with the threaded holes on the studded flange plate, only the nut needs to be installed on the flange plate at the bottom of the pressure operation equipment, so as to facilitate the fixed installation of the pressure operation equipment on the base and speed up the project progress.

[0024] Optionally, anti-slip lines are provided on the end face of the base.

[0025] By adopting the above technical solutions, during operation, some mud often adheres to the end face of the base, resulting in a relatively smooth surface of the base. By using the anti-slip function of the anti-slip lines, the situation that the staff accidentally slips when walking on the base can be reduced, thereby improving the safety of the staff during maintenance and repair to a certain extent.

[0026] In summary, the present application includes at least one of the following beneficial technical effects:

[0027] 1. When it is necessary to transport the pressure operation equipment, the connecting piece is fixed by the positioning piece, so that the connecting piece cannot rotate. Then, the pressure operation equipment is hoisted and installed and connected with the connecting piece. After the installation is completed, the positioning piece is removed and the connecting piece is no longer fixed. Then, the pressure operation equipment is hoisted by the crane and slowly rotated in the direction of the base, thereby driving the connecting piece to rotate on the support frame until the pressure operation equipment is smoothly placed on the base, and then the pressure operation equipment can be integrally carried and transported, thus saving the process of disassembling the pressure operation equipment before transportation, greatly saving time and transportation costs;

[0028] 2. When the staff needs to repair the pressure operation equipment, the pressure operation equipment is fixed on the base through the fixing piece, and then the maintenance and repair operations of the pressure operation equipment can be carried out on the base, so as to facilitate the debugging and maintenance of the pressure operation equipment;

[0029] 3. During operation, some mud often adheres to the end face of the base, resulting in a relatively smooth surface of the base. By using the anti-slip function of the anti-slip lines, the situation that the staff accidentally slips when walking on the base can be reduced, thereby improving the safety of the staff during maintenance and repair to a certain extent. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of a pressure operation equipment transportation skid according to an embodiment of the present application.

[0031] Figure 2 is a partial explosion diagram of an embodiment of the present application, aiming to show that the connecting piece is rotatably arranged on the support frame.

[0032] Figure 3 It is a schematic structural diagram of an embodiment of the present application, aiming to schematically show the installation connection between the flange at the bottom of the pressure operation equipment and the first flange.

[0033] Figure 4 It is a schematic structural diagram of an embodiment of the present application, aiming to schematically show that the external frame of the pressure operation equipment is placed stably on the base after contacting and bearing force with the base.

[0034] Figure 5 It is a schematic structural diagram of an embodiment of the present application, aiming to schematically show the installation connection between the flange at the bottom of the pressure operation equipment and the studded flange on the base.

[0035] Explanation of reference numerals: 1. Base; 11. Anti-slip pattern; 2. Support frame; 21. First support frame; 22. Second support frame; 3. Connecting piece; 31. First flange; 32. Connecting cylinder; 33. Rotating cylinder; 331. Annular groove; 332. Second through hole; 4. Pin shaft; 41. Pulling ring; 5. Sleeve; 51. First through hole; 52. Limiting groove; 6. Limiting block; 7. Lifting lug; 8. Studded flange. Detailed implementation manners

[0036] The following further describes the present application in detail with reference to the Figures 1-5 accompanying drawings.

[0037] An embodiment of the present application discloses a transportation skid for a pressure operation equipment. Refer to Figure 1 , a transportation skid for a pressure operation equipment includes a base 1, a support frame 2 is arranged on the end surface of the base 1, a connecting piece 3 is rotatably arranged on the support frame 2, and the connecting piece 3 is used for connecting with the pressure operation equipment; a positioning piece is also arranged on the support frame 2, and the positioning piece is used for fixing the connecting piece 3.

[0038] Refer to Figure 1 , Figure 2 , wherein, the connecting piece 3 includes a first flange 31, a connecting structure and a rotating structure, the rotating structure is rotatably arranged on the support frame 2, and the connecting structure is fixedly connected between the first flange 31 and the rotating structure; wherein, the first flange 31 can be set as a common ordinary flange on the market, and the first flange 31 and the flange at the bottom of the pressure operation equipment are matched by double-headed studs and nuts, so as to achieve the effect of fixed connection.

[0039] Refer to Figure 1The support frame 2 includes a first support frame 21 and a second support frame 22, and the rotating structure is rotatably arranged between the first support frame 21 and the second support frame 22; in the present embodiment, the first support frame 21 and the second support frame 22 are both arranged as a tripod, and the first support frame 21 and the second support frame 22 are both welded to the base 1, and reinforcing plates are welded on the inclined columns of the first support frame 21 and the second support frame 22, and the first support frame 21 and the second support frame 22 are both welded with support columns between the inclined columns, and the support columns are welded to the base 1; utilizing the stability of the triangle, the pressure-carrying operation equipment is placed on the first support frame 21 and the second support frame 22 as a whole, which is more stable; in addition, the first support frame 21 and the second support frame 22 can also be arranged in other shapes, that is, the effect of improving the stability of the pressure-carrying operation equipment placed on the first support frame 21 and the second support frame 22 as a whole can be achieved.

[0040] Reference Figure 1 , Figure 2 The connecting structure is a connecting cylinder 32, and the rotating structure is a rotating cylinder 33. Both the connecting cylinder 32 and the rotating cylinder 33 are hollow. Annular grooves 331 are circumferentially provided at both ends of the rotating cylinder 33. Sleeves 5 are sleeved in the annular grooves 331 at both ends. One sleeve 5 is welded to the top of the first support frame 21, and the other sleeve 5 is welded to the top of the second support frame 22. One end of the connecting cylinder 32 is welded to the middle position of the rotating cylinder 33, and the first flange 31 is welded to the other end of the connecting cylinder 32. The rotating cooperation between the rotating cylinder 33 and the sleeves 5 at both ends makes it convenient to rotate and lay the pressure-carrying equipment on the base.

[0041] Reference Figure 1 , Figure 2 , wherein the positioning member is a pin shaft 4, a first through hole 51 is formed on the sleeve 5, and a second through hole 332 is formed on the rotating cylinder 33. When the first flange 31 is rotated so that the disk surface of the first flange 31 facing away from the connecting cylinder 32 faces upward, the first through hole 51 and the second through hole 332 are directly opposite to each other, and the pin shaft 4 passes through the first through hole 51 and the second through hole 332 to fix the sleeve 5 and the rotating cylinder 33; in this embodiment, two pin shafts 4 are provided, and correspondingly, the sleeves 5 at both ends are provided with first through holes 51, and the two ends of the rotating cylinder 33 are provided with second through holes 332. The rotating cylinder 33 is fixed by two pin shafts 4, so that the rotating cylinder 33 and the sleeve 5 cannot rotate relative to each other, thereby improving the stability when the first flange 31 is installed and connected with the pressure working equipment; in order to facilitate the staff to plug and unplug the pin shaft 4, a lifting ring 41 is also welded on the pin shaft 4. In addition, the pin shaft 4 is a common product on the market, and those skilled in the art can know it after checking, so it will not be described in detail.

[0042] Reference Figure 1 , Figure 2, limiting structures are provided at both ends of the rotating cylinder 33. The limiting structures are used to limit the rotating cylinder 33 within the sleeves 5 at both ends of the rotating cylinder 33. Among them, the limiting structure is a limiting block 6. The two limiting blocks 6 are respectively welded to both ends of the rotating cylinder 33. Limiting grooves 52 are provided on the sleeves 5 at both ends. When the rotating cylinder 33 rotates to drive the limiting block 6 to rotate within the limiting groove 52, when the limiting block 6 abuts against the end of the limiting groove 52 away from the base 1, the first through hole 51 and the second through hole 332 are aligned. When the limiting block 6 abuts against the end of the limiting groove 52 close to the base 1, the first through hole 51 and the second through hole 332 are offset; by using the limiting grooves 52 at both ends and the limiting blocks 6 at both ends of the rotating cylinder 33, the rotating cylinder 33 is limited within the sleeves 5 at both ends, so that the rotating cylinder 33 cannot move left and right during rotation;

[0043] In this embodiment, the limiting block 6 is arranged as a cuboid. The rotation angle of the limiting block 6 is restricted by the limiting groove 52, so that when the limiting block 6 rotates to abut against the upper end of the limiting groove 52, the length direction of the limiting block 6 is perpendicular to the end face of the base 1. The disk surface of the first flange 31 facing away from the connecting cylinder 32 faces directly upward, and the first through hole 51 and the second through hole 332 are exactly aligned, so as to facilitate inserting the pin shaft 4 into the first through hole 51 and the second through hole 332 to fix the sleeve 5 and the rotating cylinder 33; when the limiting block 6 rotates to abut against the lower end of the limiting groove 52, the length direction of the limiting block 6 is consistent with the end face of the base 1;

[0044] In addition, the limiting angle of the limiting groove 52 on the limiting block 6 can be adjusted according to the actual situation, that is, it can achieve the effect of aligning the first through hole 51 and the second through hole 332, facilitating inserting the pin shaft 4 into the first through hole 51 and the second through hole 332 and then installing the pressure - operated equipment on the first flange 31, and rotating the pressure - operated equipment can place the pressure - operated equipment stably on the base 1.

[0045] Refer to Figure 1 , in order to facilitate the crane to hoist and transport the base 1 as a whole, lifting lugs 7 are welded to both sides of the end face of the base 1, so that the pressure - operated equipment can be hoisted and used as a whole when this transportation skid is in use; in this embodiment, the number of lifting lugs 7 is set to four, and it can also be set to other numbers, that is, the number of lifting lugs 7 can achieve the effect of improving the safety when hoisting and transporting the base 1 as a whole.

[0046] Refer to Figure 1, for the convenience of the staff to debug and repair the pressure - operated equipment, a fixing part is also provided on the base 1. The fixing part is used to fix the pressure - operated equipment on the base 1. Among them, the fixing part includes a second flange. The second flange is a stud - welded flange 8, and the stud - welded flange 8 is welded inside the base 1 and located at the center of the end face of the base 1. Compared with other flanges, the bolt holes on the stud - welded flange 8 are threaded holes, which have the advantages of flexible and simple installation, convenient operation and maintenance, and can adapt to a variety of complex working conditions. By passing a double - ended stud through the flange at the bottom of the pressure - operated equipment and then thread - mating with the threaded holes on the stud - welded flange 8, only a nut needs to be installed on the flange at the bottom of the pressure - operated equipment to stably install the pressure - operated equipment on the base 1, thus accelerating the project progress and saving the installation cost. In addition, the second flange can also be selected as other flanges according to the situation, that is, as long as the effect of facilitating the fixed installation of the pressure - operated equipment on the base 1 and stable connection can be achieved.

[0047] Refer to Figure 1 , in order to reduce the situation that the staff accidentally slips when walking on the base 1 due to the adhesion of mud on the end face of the base 1, the end face of the base 1 can be paved with lenticular pattern steel plate. By using the multiple lenticular anti - slip patterns 11 on the lenticular pattern steel plate, the safety of the staff during maintenance and repair is improved to a certain extent. Other steel plates can also be selected, that is, as long as the anti - slip effect can be achieved.

[0048] It should be noted that the sizes of the first flange 31 and the stud - welded flange 8 above can be adjusted according to the size of the flange at the bottom of the pressure - operated equipment in the actual situation, that is, as long as the effect of firmly connecting the flange at the bottom of the pressure - operated equipment with the first flange 31 or the stud - welded flange 8 can be achieved.

[0049] Refer to Figure 3 , for the convenience of understanding this application, a state diagram showing the installation and connection of the flange at the bottom of the pressure - operated equipment on the first flange 31 is presented. After the installation is completed, the pressure - operated equipment can be hoisted and rotated towards the base 1.

[0050] Refer to Figure 4 , for the convenience of understanding this application, a state diagram showing the external frame of the pressure - operated equipment being placed stably on the base 1 after contacting and bearing force with the base 1 is presented. Then, the base 1 and the pressure - operated equipment on the base 1 can be integrally hoisted and transported.

[0051] Refer to Figure 1 、 Figure 5 , for the convenience of understanding this application, a state diagram showing the installation and connection of the flange at the bottom of the pressure - operated equipment on the stud - welded flange 8 on the base 1 is presented. After the installation is completed, the pressure - operated equipment can be debugged and repaired.

[0052] The implementation principle of a transportation skid for pressure - operated equipment in an embodiment of this application is as follows: When it is necessary to transport the pressure - operated equipment, the staff rotates the first flange 31 so that the disk surface on the side of the first flange 31 facing away from the connecting cylinder 32 faces directly upward. At this time, the first through - hole 51 and the second through - hole 332 are aligned. Insert the pin shaft 4 into the first through - hole 51 and the second through - hole 332 to fix the rotating cylinder 33 in the sleeve 5. Then hoist the pressure - operated equipment above the first flange 31, and use a plurality of stud bolts and nuts to fixedly connect the first flange 31 to the flange at the bottom of the pressure - operated equipment, thereby fixedly connecting the pressure - operated equipment to the first flange 31;

[0053] The staff pulls the lifting ring 41 to extract the pin shaft 4 from the first through - hole 51 and the second through - hole 332, and no longer fixes the rotating cylinder 33 and the sleeve 5. Then use a crane to hoist the pressure - operated equipment and slowly rotate it in the direction of the base 1 until the outer frame on the pressure - operated equipment is stably placed on the base 1. Then the base 1 and the pressure - operated equipment on the base 1 can be transported, which is convenient for the overall loading and transportation of the pressure - operated equipment without disassembling it, saving time and transportation costs, and thus improving work efficiency;

[0054] When the staff needs to repair the pressure - operated equipment, hoist the pressure - operated equipment above the studded flange 8. Use a plurality of stud bolts to pass through the flange at the bottom of the pressure - operated equipment and then thread - fit with the threaded holes on the studded flange 8. Then install nuts on the flange at the bottom of the pressure - operated equipment, and further stably install the pressure - operated equipment on the base 1. Then maintenance and repair operations on the pressure - operated equipment can be carried out on the base 1. Compared with the common transportation skids that are only used for transportation, the transportation skid in this application not only has the function of transporting the pressure - operated equipment, but also has the function of facilitating the vertical installation, debugging and maintenance of the pressure - operated equipment.

[0055] The above are all the preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape and principle of this application should be covered within the protection scope of this application.

Claims

1. A transportation skid for pressure operation equipment, characterized in that: The invention comprises a base (1), wherein a support frame (2) is arranged on the base (1), a connecting member (3) is rotatably arranged on the support frame (2), the connecting member (3) is used to be connected to a pressure-operated device, and further comprises a positioning member, the positioning member is used to fix the connecting member (3); the connecting member (3) comprises a first flange (31), a connecting structure and a rotating structure, the rotating structure is rotatably arranged on the support frame (2), and the connecting structure is fixedly connected between the first flange (31) and the rotating structure; the support frame (2) comprises a first support frame (21) and a second support frame (22), the rotating structure is rotatably arranged between the first support frame (21) and the second support frame (22), and the first support frame (21) and the second support frame (21) are both arranged as tripods; The device also comprises a limiting structure, wherein the limiting structure is used to limit the rotation structure between the first support frame (21) and the second support frame (22); the connecting structure comprises a connecting cylinder (32), and the rotating structure comprises a rotating cylinder (33); the connecting cylinder (32) and the rotating cylinder (33) are both hollow, and an annular groove (331) is circumferentially provided at both ends of the rotating cylinder (33); sleeves (5) are sleeved in the annular grooves (331) at both ends, wherein one of the sleeves (5) is arranged on the first support frame (21), and the other sleeve (5) is arranged on the second support frame (22); the connecting cylinder (32) is arranged on the rotating cylinder (33) The first flange (31) is connected to the rotating cylinder (33) through the connecting cylinder (32); the positioning member includes a pin shaft (4), a first through hole (51) is provided on the sleeve (5), and a second through hole (332) is provided on the rotating cylinder (33); when the first flange (31) is rotated away from the disk surface on the side of the connecting cylinder (32) to a position away from the base (1), the first through hole (51) and the second through hole (332) are opposite to each other, and the pin shaft (4) passes through the first through hole (51) and the second through hole (332) to fix the sleeve (5) and the rotating cylinder (33); a lifting ring (41) is provided on the pin shaft (4).

2. The transportation skid of a pressure operation device according to claim 1, characterized in that: The sleeves (5) at both ends are provided with limiting grooves (52), and the limiting structure comprises a limiting block (6), and the limiting block (6) is rotatably arranged in the limiting groove (52). When the limiting block (6) is in contact with the end of the limiting groove (52) away from the base (1), the first through hole (51) and the second through hole (332) are opposite to each other; when the limiting block (6) is in contact with the end of the limiting groove (52) close to the base (1), the first through hole (51) and the second through hole (332) are staggered.

3. The transportation skid of a pressure operation device according to claim 1, characterized in that: The base (1) is also provided with a fixing part, and the fixing part is used to fix the pressure-operating equipment on the base (1).

4. The transportation skid of a pressure operation device according to claim 3, characterized in that: The fixing member comprises a second flange, and the second flange is arranged on the base (1).

5. The transportation skid of a pressure operation device according to claim 4, characterized in that: The second flange is a threaded flange (8).

6. The transport skid of a pressure operation device according to claim 1, characterized in that: Anti-slip grooves (11) are provided on the end surface of the base (1).

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