Vulcanization processing mold for large clamp sealing ring and processing technology of vulcanization processing mold
Through the vulcanization processing process of large clamp sealing rings made in segments, the problem of high production costs and poor performance of large clamp sealing rings is solved through the vulcanization process of large clamp sealing rings, and the effect of reducing costs and improving performance is achieved.
Patent Information
- Application Number
- CN202411361370.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2025-02-11
AI Technical Summary
The production cost of large clamp sealing rings is high and their performance is affected, and the prior art is difficult to effectively reduce costs and improve performance.
The vulcanization process of large clamp sealing ring made in segments is adopted. The rubber embryo is vulcanized into a half-stage sealing ring through a molding mold, and a complete sealing ring is formed through pressurized vulcanization connection, reducing joints and improving performance.
The production cost of large clamp seals is reduced and the performance and stability of the seals are improved through jointless design.
Smart Images
Figure CN119408033A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of vulcanization processing of sealing rings, and in particular to a vulcanization processing mold and a processing technology thereof for a large clamp sealing ring. Background Art
[0002] Grooved pipe fitting connection technology, also known as clamp connection technology, is a connection technology used for gas or liquid pipelines, with the advantages of fast installation, safety and reliability, easy installation, and easy maintenance. The process of grooved pipe fitting connection is to install the clamp seal ring in the groove of the grooved fitting, then align the pipe to be connected with the installed pipe, then slide the grooved fitting to the connection of the pipe, and fasten the grooved fitting to the connection of the pipe through the clamp to complete the connection of the pipe.
[0003] The connection of the grooved pipe joint requires a clamp seal ring. The existing production method of the clamp seal ring is to produce a mold of a corresponding size according to the size of the clamp seal ring to be produced, and then the clamp seal ring is integrally produced and formed through a vulcanization process.
[0004] However, in the process of connecting large-diameter grooved pipe joints, large clamp seals are required. However, in the conventional production method of clamp seals, the larger the diameter of the clamp seal, the larger the mold required for production, so the production cost of large-diameter clamp seals will increase significantly.
[0005] In addition, another way to produce large clamp seals is to divide the large clamp seals into multiple sections for production, and bond the seals of different sections with glue after production. Although this production method of large clamp seals can reduce production costs to a certain extent, the large clamp seals formed by bonding will have several joints, which will affect the performance of the large clamp seals. Summary of the invention
[0006] In order to solve the above problems, the present application provides a vulcanization processing mold and a processing technology for a large clamp sealing ring.
[0007] The present application provides a vulcanization processing mold and processing technology of a large clamp seal ring, which adopts the following technical solutions: A vulcanization process for a large clamp seal ring, comprising: S1. Press out a number of green embryos according to the designed size; S2, placing a raw embryo into the processing hole of the forming mold, using a plugging piece to plug both ends of the processing hole, pressurizing and vulcanizing the raw embryo to form a first section of semi-vulcanized large clamp sealing ring, and the first section of semi-vulcanized large clamp sealing ring constitutes a manufactured sealing ring; S3, clamping one end of the manufactured sealing ring at one end of the processing hole, placing another green blank into the processing hole and arranged in the gap with the manufactured sealing ring, and using a blocking piece to block the other end of the processing hole; S4, pressurize and vulcanize another green sheet to form another section of semi-vulcanized large clamp sealing ring fused with the manufactured sealing ring, and the other section of semi-vulcanized large clamp sealing ring and the manufactured sealing ring in S3 together form a new manufactured sealing ring; S5, repeat S3 and S4 until the last section of the green embryo is pressurized and vulcanized; S6, placing the two ends of the manufactured sealing ring in the processing hole respectively and clamping them by the forming mold, placing the last section of the green embryo in the processing hole, and arranging the gap between the two ends of the last section of the green embryo and the two ends of the manufactured sealing ring; S7. Pressurize and vulcanize the last section of the green sheet to form a large clamp seal ring connected end to end.
[0008] By adopting the above technical scheme, before making a large clamp seal ring, the large clamp seal ring is divided into different sections, and the rubber raw material is pressed into a green blank of the required size according to the length of the different sections. The green blank is vulcanized in the processing hole to form semi-vulcanized clamp seal rings of different sections, and the production cost of the large seal ring is reduced by making the large clamp seal ring in sections. The semi-vulcanized clamp seal ring is vulcanized together with the next green blank to form a finished seal ring. When the final section of the green blank is vulcanized, both ends of the finished seal ring are vulcanized and connected with the final section of the green blank to form a complete large clamp seal ring. By forming a semi-vulcanized clamp seal ring and vulcanizing it together with the final section of the green blank to form a complete large clamp seal ring, a jointless large clamp seal ring is formed, thereby enhancing the performance of the large clamp seal ring.
[0009] Optionally, step S6 includes: S61, placing one end of the manufactured sealing ring into the processing hole and setting it at one end of the processing hole; S62, placing the last section of the green blank into the processing hole, and determining the distance between the other end of the manufactured sealing ring and the end of the last section of the green blank away from the manufactured sealing ring according to the size of the required large clamp sealing ring; S63. Use a forming mold to clamp the two ends of the manufactured sealing ring and the last section of the raw embryo.
[0010] By adopting the above technical scheme, in the process of manufacturing the final large clamp seal ring, one end of the manufactured seal ring is first positioned, and then the placement position of the other end of the manufactured seal ring is determined according to the required size of the large clamp seal ring, and the rubber material is filled in the gap between the raw embryo and the manufactured seal ring through pressurized vulcanization, thereby forming a complete large clamp seal ring, thereby reducing the probability of errors in the large clamp seal ring.
[0011] Optionally, a vulcanization process for a large clamp seal ring also includes: S8. Put the processed large clamp sealing ring on the shaping ring and perform vulcanization shaping.
[0012] By adopting the above technical solution, the large clamp seal ring is sleeved on the shaping ring for vulcanization, so that the length of the produced large clamp seal ring is fixed, thereby reducing the production error of the large clamp seal ring.
[0013] Optionally, a vulcanization process for a large clamp seal ring also includes: S9. Perform secondary vulcanization on the large clamp seal ring after vulcanization and shaping.
[0014] By adopting the above technical solution and performing secondary vulcanization on the large clamp seal ring, the performance of the large clamp seal ring can be improved, the performance of the large clamp seal ring can be made more stable, and the vulcanization of the large clamp seal ring can be made more complete.
[0015] A vulcanization processing mold for a large clamp sealing ring, comprising: A molding die, comprising an upper die and a lower die, wherein the upper die covers the lower die, a first molding groove is formed on a side of the upper die facing the lower die, and a second molding groove is formed on a side of the lower die facing the upper die, wherein the first molding groove and the second molding groove together form a processing hole, and a cross section of the processing hole is consistent with a cross section of a large clamp seal ring to be processed; A plugging piece, detachably connected to both ends of the forming die, the plugging piece is used to plug the processing hole; The shaping ring is used to shape the initially formed large clamp sealing ring.
[0016] By adopting the above technical solution, when vulcanizing the large clamp seal ring, the upper mold and the lower mold are separated, and then the green embryo is placed in the first molding groove, the upper mold and the lower mold are covered, and the processing hole is blocked by the blocking piece at the same time, and the green embryo fills the processing hole through vulcanization processing, thereby forming a large clamp seal ring segment of the required shape. After the large clamp seal ring is manufactured, the shaping ring can set the length of the large clamp seal ring to meet the production requirements of the large clamp seal ring.
[0017] Optionally, a groove wall of the second forming groove is engraved with a positioning line, and the positioning line is used to determine the placement position of the green embryo and the manufactured sealing ring in the processing hole.
[0018] By adopting the above technical solution, the engraved positioning line can facilitate the placement of the manufactured sealing ring and the green blank, reducing the probability of the manufactured sealing ring and the green blank being too far or too close to each other, thereby causing a joint.
[0019] Optionally, the upper mold includes a first left mold and a first right mold, the first left mold is detachably connected to the first right mold, and the lower mold includes a second left mold and a second right mold, and the second left mold is detachably connected to the second right mold.
[0020] By adopting the above technical solution, the upper mold and the lower mold are separated, which facilitates the processing of the upper mold and the lower mold, thereby reducing the processing costs of the upper mold and the lower mold.
[0021] Optionally, positioning pieces are connected to both sides of the molding die, and the positioning pieces are used to position the molding die.
[0022] By adopting the above technical solution, the positioning member positions the molding die, thereby reducing the probability of the molding die shaking when performing vulcanization molding of the green embryo.
[0023] Optionally, the positioning member includes a first positioning plate and a second positioning plate, and both sides of the first left mold, the first right mold, the second left mold, and the second right mold are connected to the first positioning plate and the second positioning plate.
[0024] By adopting the above technical solution, the first left mold, the first right mold, the second left mold and the second right mold are positioned on both sides, which further reduces the probability of shaking of the molding mold, and at the same time reduces the probability of misalignment between the first left mold and the first right mold, and reduces the probability of misalignment between the second left mold and the second right mold.
[0025] Optionally, a pressurized guide column is fixedly connected to one end of the lower mold toward the upper mold, and the number of the pressurized guide column is at least 2. A guide hole is opened at one end of the upper mold toward the lower mold, and the pressurized guide column is slidably connected to the hole wall of the guide hole.
[0026] By adopting the above technical solution, at least two pressurized guide posts and guide holes complete the determination of the relative movement direction between the upper mold and the lower mold, which facilitates the pressurized vulcanization of the green embryo between the upper mold and the lower mold.
[0027] Compared with the prior art, the present invention has at least one of the following beneficial technical effects: 1. The present invention manufactures the large clamp seal ring in sections, and does not need to produce a molding mold with the same caliber as the large clamp seal ring, thereby reducing the production cost of the large clamp seal ring. At the same time, in the process of producing the clamp seal ring in sections, the semi-vulcanized seal ring is vulcanized together with the green embryo to form a finished seal ring, and the finished seal ring is vulcanized and connected with the green embryo, thereby producing a large clamp seal ring without a joint, thereby enhancing the performance of the large seal ring; 2. After forming the sealing ring connected end to end, the present invention puts the sealing ring on the shaping ring for primary vulcanization shaping, thereby fixing the length of the sealing ring, and then performs secondary vulcanization on the sealing ring after the primary vulcanization shaping, thereby improving the performance of the sealing ring and making the sealing ring vulcanized more fully; 3. During vulcanization, the positions of the green blank and the manufactured sealing ring are determined by the positioning line engraved on the second molding groove, thereby facilitating the control of the vulcanization connection between the manufactured sealing ring and the green blank, thereby reducing the probability of a joint being generated between the manufactured sealing ring and the green blank due to being too close or too far apart during vulcanization. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 It is a schematic diagram of the external structure of the molding die in the embodiment of the present application.
[0029] Figure 2 It is a structural schematic diagram of the lower mold in the embodiment of the present application.
[0030] Figure 3 It is a schematic diagram of the structure of the shaping ring in the embodiment of the present application.
[0031] Figure 4 It is a flow chart of the vulcanization process of a large clamp seal ring in an embodiment of the present application.
[0032] In the figure: 1. forming mold; 11. processing hole; 12. upper mold; 121. first forming groove; 122. first left mold; 123. first right mold; 124. guide hole; 13. lower mold; 131. second forming groove; 132. positioning line; 1321. raw embryo placement line; 1322. manufactured sealing ring placement line; 133. second left mold; 134. second right mold; 135. pressurized guide column; 2. sealing member; 3. shaping ring; 4. positioning member; 41. first positioning plate; 42. second positioning plate. DETAILED DESCRIPTION
[0033] The following is combined with Figure 1-Figure 4 This application is described in further detail.
[0034] The embodiment of the present application discloses a vulcanization processing mold and a processing technology of a large clamp seal ring. Figure 1 , Figure 2 and Figure 3 A vulcanization processing mold for a large clamp sealing ring includes a forming mold 1, a sealing piece 2 and a shaping ring 3.
[0035] The molding die 1 comprises an upper die 12 and a lower die 13. The bottom end of the upper die 12 covers the top end of the lower die 13. The bottom end of the upper die 12 is provided with a first molding groove 121, and the top end of the lower die 13 is provided with a second molding groove 131. When the upper die 12 and the lower die 13 are covered, the first molding groove 121 and the second molding groove 131 jointly form a processing hole 11. The cross section of the processing hole 11 is consistent with the cross section of the large clamp seal ring to be processed. The plugging member 2 is located at both ends of the molding die 1. The plugging member 2 is detachably connected to the molding die 1. When the plugging member 2 is connected to the molding die 1, the plugging member 2 blocks the processing hole 11. The shaping ring 3 is arranged at intervals from the molding die 1, and the outer ring size of the shaping ring 3 is the inner ring size of the large clamp seal ring to be formed.
[0036] When manufacturing a large clamp seal ring, the upper mold 12 and the lower mold 13 are separated first, and the green embryo made of rubber material is placed in the first molding groove 121, and then the lower mold 13 and the lower mold 13 are covered, and the first molding groove 121 and the second molding groove 131 jointly form a processing hole 11, and then the two ends of the processing hole 11 are blocked by the blocking member 2, and the green embryo is vulcanized to fill the processing hole 11 by pressurized vulcanization, so as to form the required large clamp seal ring segment, and then the manufactured large clamp seal ring segment is further vulcanized and connected with the green embryo, and finally a large clamp seal ring is formed. The processing of the large clamp seal ring is realized.
[0037] Reference Figure 1 and Figure 2 The groove wall of the second molding groove 131 is engraved with positioning lines 132, and the positioning lines 132 include a green embryo placement line 1321 and a manufactured sealing ring placement line 1322. The placement position of the green embryo is determined by the green embryo placement line 1321, and the placement position of the manufactured sealing ring is determined by the manufactured sealing ring placement line 1322, thereby determining the interval between the green embryo and the manufactured sealing ring, and further reducing the probability of joints in the large clamp sealing ring produced after final production and molding due to the green embryo and the manufactured sealing ring being too far or too close during vulcanization.
[0038] Reference Figure 1 and Figure 2The upper mold 12 includes a first left mold 122 and a first right mold 123. The first left mold 122 is fixedly connected to one end facing the first right mold 123 with a first clamping block (not marked in the drawings). The first clamping block and the end of the first left mold 122 together form a first clamping slot (not marked in the drawings). The first right mold 123 is fixedly connected to one end facing the first left mold 122 with a second clamping block (not marked in the drawings). The second clamping block and the end of the first right mold 123 together form a second clamping slot (not marked in the drawings). The first clamping block clamps the slot wall of the second clamping slot, and the second clamping block clamps the slot wall of the first clamping slot. The lower mold 13 includes a second left mold 133 and a second right mold 134. The connection method of the second left mold 133 and the second right mold 134 is consistent with the connection method of the first left mold 122 and the first right mold 123.
[0039] The upper mold 12 is split into a first left mold 122 and a first right mold 123, and the lower mold 13 is split into a second left mold 133 and a second right mold 134, thereby facilitating the production of the upper mold 12 and the lower mold 13 and reducing the processing cost of the upper mold 12 and the lower mold 13. The upper mold 12 and the lower mold 13 can also be split during transportation, thereby facilitating the transportation of the upper mold 12 and the lower mold 13.
[0040] Reference Figure 1 and Figure 2 The two opposite sides of the molding die 1 are connected with positioning members 4, which include a first positioning plate 41 and a second positioning plate 42. The first left mold 122, the first right mold 123, the second left mold 133 and the second right mold 134 are fixedly connected with the first positioning plate 41 and the second positioning plate 42. Positioning holes are provided on the first positioning plate 41 and the second positioning plate 42.
[0041] By using the first positioning plate 41 and the second positioning plate 42 to respectively position the first left mold 122, the first right mold 123, the second left mold 133 and the second right mold 134, the probability of shaking of the molding mold 1 during the pressurization vulcanization process is reduced, and the probability of misalignment of the first left mold 122 and the first right mold 123 during the pressurization vulcanization process is reduced, and the probability of misalignment of the second left mold 133 and the second right mold 134 during the pressurization vulcanization process is reduced.
[0042] The lower mold 13 is fixedly connected to one end facing the upper mold 12 with a pressurizing guide column 135, and the number of the pressurizing guide columns 135 is at least 2, and preferably 4. The upper mold 12 is provided with guide holes 124 at one end facing the lower mold 13, and the number of the guide holes 124 is the same as the number of the pressurizing guide columns 135. The side wall of the pressurizing guide column 135 is in sliding contact with the hole wall of the guide hole 124.
[0043] The plugging member 2 is provided with a discharge hole (not marked in the drawings), and the plugging member 2 can discharge the excess liquid rubber in the processing hole 11 during the pressurized vulcanization by providing the discharge hole.
[0044] The implementation principle of the vulcanization processing mold of a large clamp sealing ring in the embodiment of the present application is: when making a large clamp sealing ring, the raw embryo is clamped between the upper mold 12 and the lower mold 13 by the upper mold 12 and the lower mold 13, and the processing hole 11 is blocked with the sealing piece 2, and the raw embryos of different sections are vulcanized and connected respectively to finally form a large clamp sealing ring, and the manufactured large clamp sealing ring is set on the shaping ring 3 so that the length of the large clamp sealing ring meets the required length of the large clamp sealing ring, and the production of the large clamp sealing ring is completed.
[0045] A vulcanization process for large clamp seal rings, refer to Figure 4 , including the following steps: S1. Divide the large clamp seal ring into several sections, and press the rubber raw material into several green embryos according to the lengths of the divided large seal ring sections; S2, placing the first section of pressed green embryo into the first molding groove 121, closing the mold 12, placing the plugging member 2 against both ends of the molding mold 1, pressurizing and vulcanizing the green embryo so that the green embryo fills the processing hole 11, forming the first section of semi-vulcanized large clamp sealing ring, and the first section of semi-vulcanized large clamp sealing ring constitutes a finished sealing ring; S3, separate the upper mold 12 and the lower mold 13, separate the plugging member 2 and the molding mold 1, move the manufactured sealing ring, and place one end of the manufactured sealing ring in contact with the manufactured sealing ring placement line 1322. Place another green embryo into the first molding groove 121, cover the upper mold 12, and use the plugging member 2 to block the end of the processed hole 11 away from the manufactured sealing ring; S4, pressurize and vulcanize another green sheet, and the green sheet is pressurized and vulcanized to form another section of semi-vulcanized large clamp seal ring which is vulcanized and fused to one end of the manufactured seal ring. The semi-vulcanized seal ring at the other end and the manufactured seal ring in S3 together form a new manufactured seal ring; S5, repeat S3 and S4 to vulcanize the remaining green embryos until the last section of green embryos is vulcanized; S6, placing the two ends of the manufactured sealing ring in the processing hole 11, and then placing the last section of the green embryo between the two ends of the manufactured sealing ring, so that the two ends of the last section of the green embryo and the two ends of the manufactured sealing ring are arranged in a gap; S61, open the upper mold 12 and the lower mold 13, move the manufactured sealing ring, and make one end of the manufactured sealing ring fit the manufactured sealing ring placement line 1322; S62, placing the last section of the green embryo in the first molding groove 121, so that one end of the last section of the green embryo is in contact with the green embryo placement line 1321. Determine the distance between the other end of the manufactured sealing ring and the last section of the green embryo away from the green embryo placement line 1321 according to the size of the required large clamp sealing ring; S63, the upper mold 12 is covered with the lower mold 13 to clamp the last section of the green embryo and the two ends of the manufactured sealing ring; S7, pressurize and vulcanize the last section of the green sheet to form a large clamp seal ring connected end to end; S8, the large clamp sealing ring formed by processing and connected end to end is set on the shaping ring 3, and vulcanized and shaped so that the length of the sealing ring of the large clamp meets the required sealing ring length; S9. Perform secondary vulcanization on the large clamp seal ring that has completed vulcanization and finalization to optimize the performance of the large clamp seal ring and make the vulcanization of the large clamp seal ring more complete.
[0046] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. A vulcanization process for a large clamp seal ring, characterized in that: The following steps are involved: S1. Press out a number of green embryos according to the designed size; S2, placing a raw embryo into the processing hole (11) of the forming mold (1), using the plugging member (2) to plug the two ends of the processing hole (11), pressurizing and vulcanizing the raw embryo to form a first section of semi-vulcanized large clamp sealing ring, and the first section of semi-vulcanized large clamp sealing ring constitutes a finished sealing ring; S3, clamping one end of the manufactured sealing ring at one end of the processing hole (11), placing another green blank into the processing hole (11) and arranged in the gap with the manufactured sealing ring, and using the sealing member (2) to seal the other end of the processing hole (11); S4, pressurize and vulcanize another green sheet to form another section of semi-vulcanized large clamp sealing ring fused with the manufactured sealing ring, and the other section of semi-vulcanized large clamp sealing ring and the manufactured sealing ring in S3 together form a new manufactured sealing ring; S5, repeat S3 and S4 until the last section of the green embryo is pressurized and vulcanized; S6, placing the two ends of the manufactured sealing ring in the processing hole (11) respectively and clamping them by the forming mold (1), placing the last section of the green embryo in the processing hole (11), and arranging the two ends of the last section of the green embryo with the two ends of the manufactured sealing ring in a gap; S7. Pressurize and vulcanize the last section of the green sheet to form a large clamp seal ring connected end to end.
2. The vulcanization process of a large clamp seal ring according to claim 1, characterized in that: Step S6 includes: S61, placing one end of the manufactured sealing ring into the processing hole (11) and setting it at one end of the processing hole (11); S62, placing the last section of the green blank into the processing hole (11), and determining the distance between the other end of the manufactured sealing ring and the end of the last section of the green blank facing away from the manufactured sealing ring according to the size of the required large clamp sealing ring; S63. Use the forming mold (1) to clamp the two ends of the manufactured sealing ring and the last section of the green embryo.
3. The vulcanization process of a large clamp seal ring according to claim 1, characterized in that: Also includes: S8, the processed large clamp sealing ring is placed on the shaping ring (3) and vulcanized and shaped.
4. The vulcanization process of a large clamp seal ring according to claim 3, characterized in that: Also includes: S9. Perform secondary vulcanization on the large clamp seal ring after vulcanization and shaping.
5. A vulcanization processing mold for a large clamp seal ring, applied to the vulcanization processing technology of the large clamp seal ring according to any one of claims 1 to 4, characterized in that: include: A molding die (1), comprising an upper die (12) and a lower die (13), wherein the upper die (12) covers the lower die (13), a first molding groove (121) is formed on a side of the upper die (12) facing the lower die (13), and a second molding groove (131) is formed on a side of the lower die (13) facing the upper die (12), wherein the first molding groove (121) and the second molding groove (131) together form a processing hole (11), and the cross section of the processing hole (11) is consistent with the cross section of a large clamp seal ring to be processed; A blocking piece (2) detachably connected to the two ends of the molding die (1), the blocking piece (2) being used to block the processing hole (11); The shaping ring (3) is used to shape the initially formed large clamp sealing ring.
6. The vulcanization processing mold for a large clamp seal ring according to claim 5, characterized in that: The groove wall of the second molding groove (131) is engraved with a positioning line (132), and the positioning line (132) is used to determine the placement position of the green embryo and the manufactured sealing ring in the processing hole (11).
7. The vulcanization processing mold for a large clamp seal ring according to claim 5, characterized in that: The upper mold (12) comprises a first left mold (122) and a first right mold (123), wherein the first left mold (122) is detachably connected to the first right mold (123), and the lower mold (13) comprises a second left mold (133) and a second right mold (134), wherein the second left mold (133) is detachably connected to the second right mold (134).
8. The vulcanization processing mold for a large clamp seal ring according to claim 7, characterized in that: Positioning members (4) are connected to both sides of the molding die (1), and the positioning members (4) are used to position the molding die (1).
9. The vulcanization processing mold for a large clamp seal ring according to claim 8, characterized in that: The positioning member (4) comprises a first positioning plate (41) and a second positioning plate (42), and both sides of the first left mold (122), the first right mold (123), the second left mold (133) and the second right mold (134) are connected to the first positioning plate (41) and the second positioning plate (42).
10. The vulcanization processing mold for a large clamp seal ring according to claim 5, characterized in that: A pressurizing guide column (135) is fixedly connected to one end of the lower mold (13) facing the upper mold (12), and the number of the pressurizing guide columns (135) is at least 2. A guide hole (124) is opened at one end of the upper mold (12) facing the lower mold (13), and the pressurizing guide column (135) is slidably connected to the hole wall of the guide hole (124).