Self-sealing multi-layer fusion forming process for steel wire mesh composite pipe

Abstract

This invention discloses a self-sealing multi-layer fusion molding process for steel wire mesh composite pipes, comprising the following steps: S1: Cutting the steel wire mesh composite pipe and grinding the end face and chamfering of the inner and outer walls of the port; S2: Partial activation heating of the inner wall, cross-section, and outer wall of the port of the steel wire mesh composite pipe; S3: Selecting a three-layer composite seepage-proof sleeve, the sleeve being integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer, and coaxially nesting the seepage-proof sleeve into the port of the steel wire mesh composite pipe; S4: Preparing a steel wire impregnation molten material ring, a main seepage-proof molten material ring, and an outer protective molten material ring, and sequentially coaxially fitting the three molten material rings onto the end face of the pipe port. This invention, through the simultaneous co-melting molding of the embedded three-layer seepage-proof sleeve and the three-layer functional molten material rings, seals seepage channels from the inner wall, cross-section, and outer wall of the pipe in three dimensions. The multi-layer structure is fused and integrated without layering interfaces. Combined with gradient preheating and pressure holding cooling processes, it exhibits excellent seepage-proof performance.

Description

Technical Field

[0001] This invention relates to the field of steel wire mesh composite pipe processing technology, and in particular to a self-sealing multi-layer welding forming process for steel wire mesh composite pipe. Background Technology

[0002] Steel wire mesh reinforced polyethylene composite pipes, with their high-strength steel wire mesh reinforcement, possess advantages such as high pressure resistance, high toughness, and excellent anti-settlement performance, and are widely used in municipal water supply and drainage, fire-fighting water supply, industrial fluid transportation, and agricultural irrigation projects. After being cut to length, the steel wire mesh is directly exposed on the pipe ends, resulting in numerous gaps between the wires, micro-gaps at the interface, and transition gaps between the inner and outer walls at the ends. These are critical weak points for pipe leakage and failure.

[0003] Traditional sealing processes often employ a single-layer molten material coating on the end face or a multi-layer coating method on the outside to achieve port sealing. This only seals the outer cross-section of the pipe and fails to provide effective waterproofing at the interface between the inner wall of the pipe and the steel wire. Under conditions of long-term water pressure fluctuations, alternating hot and cold cycles, and slight foundation settlement, water can easily seep into the pipe's inner wall through micro-cracks, continuously penetrating inwards along the interface between the steel wire mesh and polyethylene, causing problems such as steel wire corrosion, interface delamination, pipe bulging, and port cracking and leakage. Furthermore, in traditional layer-by-layer external coating processes, each welded layer cures sequentially, resulting in low interlayer bonding strength. Long-term use easily leads to interlayer peeling and micro-crack propagation. Therefore, a self-sealing multi-layer fusion forming process for steel wire mesh composite pipes is proposed to address these issues. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes a self-sealing multi-layer welding forming process for steel wire mesh composite pipes to solve the above problems.

[0005] This invention proposes a self-sealing multi-layer welding forming process for steel wire mesh composite pipes, comprising the following steps:

[0006] S1: Cut the steel wire mesh composite pipe and grind the end face and chamfer the inner and outer walls of the port of the steel wire mesh composite pipe;

[0007] S2: Zoned activation heating of the inner wall, cross-section, and outer wall of the steel wire mesh composite pipe port;

[0008] S3: Select a three-layer composite seepage-proof sleeve. The sleeve is integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer. The seepage-proof sleeve is coaxially nested into the inside of the steel wire mesh composite pipe port.

[0009] S4: Prepare a steel wire wetted molten material ring, a main anti-seepage molten material ring, and an outer protective molten material ring, and coaxially sleeve the three molten material rings on the end face of the pipe end in sequence;

[0010] S5: It adopts a double-step annular hot pressing mold, and the mold interior simultaneously extrudes three layers of molten material rings and the outer edge of the anti-seepage sleeve;

[0011] S6: After molding, the mold is not depressurized and is slowly cooled and solidified until the sleeve and end face fusion layer are completely set. After releasing the pressure, it is naturally cooled to room temperature.

[0012] In a preferred embodiment, in step S1, after the cutting is completed, a double-sided rotary sand mill is used for synchronous processing, and after the grinding is completed, high-pressure drying nitrogen is used to purge the port debris.

[0013] In a preferred embodiment, in step S2, the inner wall heating temperature range is 55-65℃, the cross-sectional heating temperature range is 70-80℃, and the outer wall heating temperature range is 55-65℃.

[0014] In a preferred embodiment, in step S2, the infrared heating time is controlled to be 25-50 seconds, and the heating range only covers a 10-30 mm area at the pipe end.

[0015] In a preferred embodiment, in step S3, the wall thickness of the anti-seepage sleeve is set to 1.2-1.8 mm, the outer edge of the sleeve extends 2-3 mm beyond the end face of the pipe, and the mass ratio of the three layers of the sleeve is 70% tough PE layer, 22% anti-seepage modified layer, and 8% coupling fusion layer.

[0016] In a preferred embodiment, in step S4, 1.0%-1.5% silane coupling agent is added to the steel wire impregnation ring, 2.0%-3.0% antioxidant anti-seepage resin is added to the main anti-seepage ring, and the overall total thickness of the three-layer molten ring is maintained at 0.9-1.6 mm.

[0017] In a preferred embodiment, in step S5, the mold constant temperature is controlled at 122-130℃, the molding pressure is 0.3-0.6MPa, the holding time is 20-45s, the inner step of the mold extrudes the outer edge of the anti-seepage sleeve, and the outer step simultaneously presses the outer edge of the three-layer molten material ring.

[0018] In a preferred embodiment, in step S6, the cooling rate during the slow cooling stage is kept constant at 1.5℃ / min, and the mold clamping pressure is maintained throughout the process. The pressure is released only after the multi-layer welded structure has completely solidified.

[0019] The beneficial effects of this invention are:

[0020] This invention adopts an embedded three-layer composite anti-seepage sleeve combined with a three-layer molten material ring co-melted molding structure on the end face. Unlike the traditional process of only coating and sealing the outside, it is the first to build an inner anti-seepage barrier inside the pipe end, blocking the channel for water to seep through the interface between the inner wall of the pipe and the steel wire.

[0021] This invention enhances the surface activity of the pipe end through zoned activation and preheating, and combines it with a three-layer molten material ring structure with differentiated functions to achieve the functions of steel wire gap wetting and filling, main body waterproofing and seepage prevention, and surface protection and crack resistance. Combined with the synchronous constant temperature molding inside and outside of the double-step mold, the seepage prevention sleeve and the three-layer molten material ring melt and interweave with each other to form an integrated multi-layer fusion sealing structure without layering and gaps.

[0022] This invention employs a pressure-holding, slow-speed gradient cooling and shaping process to avoid interface gaps and residual stress caused by temperature difference shrinkage in multi-layer welded structures, resulting in uniform and stable molding quality. Detailed Implementation

[0023] The present invention will be further explained below with reference to specific embodiments.

[0024] Example 1

[0025] This embodiment proposes a self-sealing multi-layer welding forming process for steel wire mesh composite pipes, including the following steps:

[0026] S1: Cut the steel wire mesh composite pipe and grind the end face and chamfer the inner and outer walls of the port of the steel wire mesh composite pipe;

[0027] S2: Zoned activation heating of the inner wall, cross-section, and outer wall of the steel wire mesh composite pipe port;

[0028] S3: Select a three-layer composite seepage-proof sleeve. The sleeve is integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer. The seepage-proof sleeve is coaxially nested into the inside of the steel wire mesh composite pipe port.

[0029] S4: Prepare a steel wire wetted molten material ring, a main anti-seepage molten material ring, and an outer protective molten material ring, and coaxially sleeve the three molten material rings on the end face of the pipe end in sequence;

[0030] S5: It adopts a double-step annular hot pressing mold, and the mold interior simultaneously extrudes three layers of molten material rings and the outer edge of the anti-seepage sleeve;

[0031] S6: After molding, the mold is not depressurized and is slowly cooled and solidified until the sleeve and end face fusion layer are completely set. After releasing the pressure, it is naturally cooled to room temperature.

[0032] In step S1, after cutting, a double-sided rotary sander is used for simultaneous processing. After sanding, high-pressure dry nitrogen is used to purge the debris from the end. In step S2, the inner wall heating temperature range is 55℃, the cross-section heating temperature range is 70℃, and the outer wall heating temperature range is 55℃. In step S2, the infrared heating time is controlled at 25s, and the heating range only covers a 10mm area at the pipe end. In step S3, the wall thickness of the anti-seepage sleeve is set to 1.2mm, the outer edge of the sleeve extends 2mm beyond the pipe end face, and the three-layer mass ratio of the sleeve is 70% tough PE layer, 22% anti-seepage modification layer, and 8% coupling fusion layer. In step S4, 1.0% silane coupling agent is added to the steel wire impregnation ring, and 2.0% antioxidant anti-seepage resin is added to the main anti-seepage ring. The overall total thickness of the three-layer molten ring is maintained at 0.9mm. In step S5, the mold temperature is controlled at 122℃, the molding pressure is 0.3MPa, and the holding time is 20s. The inner step of the mold presses against the outer edge of the anti-seepage sleeve, while the outer step simultaneously presses against the outer edge of the three-layer molten material ring. In step S6, the cooling rate is kept constant at 1.5℃ / min during the slow cooling stage. The mold clamping pressure is maintained throughout the process, and the pressure is released only after the multi-layer welded structure has completely solidified.

[0033] Example 2

[0034] This embodiment proposes a self-sealing multi-layer welding forming process for steel wire mesh composite pipes, including the following steps:

[0035] S1: Cut the steel wire mesh composite pipe and grind the end face and chamfer the inner and outer walls of the port of the steel wire mesh composite pipe;

[0036] S2: Zoned activation heating of the inner wall, cross-section, and outer wall of the steel wire mesh composite pipe port;

[0037] S3: Select a three-layer composite seepage-proof sleeve. The sleeve is integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer. The seepage-proof sleeve is coaxially nested into the inside of the steel wire mesh composite pipe port.

[0038] S4: Prepare a steel wire wetted molten material ring, a main anti-seepage molten material ring, and an outer protective molten material ring, and coaxially sleeve the three molten material rings on the end face of the pipe end in sequence;

[0039] S5: It adopts a double-step annular hot pressing mold, and the mold interior simultaneously extrudes three layers of molten material rings and the outer edge of the anti-seepage sleeve;

[0040] S6: After molding, the mold is not depressurized and is slowly cooled and solidified until the sleeve and end face fusion layer are completely set. After releasing the pressure, it is naturally cooled to room temperature.

[0041] In step S1, after cutting, a double-sided rotary sander is used for simultaneous processing. After sanding, high-pressure dry nitrogen is used to purge the debris from the end. In step S2, the inner wall heating temperature range is 58℃, the cross-section heating temperature range is 72℃, and the outer wall heating temperature range is 58℃. In step S2, the infrared heating time is controlled at 30s, and the heating range only covers a 15mm area at the pipe end. In step S3, the wall thickness of the anti-seepage sleeve is set to 1.4mm, the outer edge of the sleeve extends 2mm beyond the pipe end face, and the three-layer mass ratio of the sleeve is 70% tough PE layer, 22% anti-seepage modification layer, and 8% coupling fusion layer. In step S4, 1.2% silane coupling agent is added to the steel wire impregnation ring, and 2.2% antioxidant anti-seepage resin is added to the main anti-seepage ring. The overall total thickness of the three-layer molten ring is maintained at 1.1mm. In step S5, the mold temperature is controlled at 125℃, the molding pressure is 0.4MPa, and the holding time is 30s. The inner step of the mold presses against the outer edge of the anti-seepage sleeve, while the outer step simultaneously presses against the outer edge of the three-layer molten material ring. In step S6, the cooling rate is kept constant at 1.5℃ / min during the slow cooling stage. The mold clamping pressure is maintained throughout the process, and the pressure is released only after the multi-layer welded structure has completely solidified.

[0042] Example 3

[0043] This embodiment proposes a self-sealing multi-layer welding forming process for steel wire mesh composite pipes, including the following steps:

[0044] S1: Cut the steel wire mesh composite pipe and grind the end face and chamfer the inner and outer walls of the port of the steel wire mesh composite pipe;

[0045] S2: Zoned activation heating of the inner wall, cross-section, and outer wall of the steel wire mesh composite pipe port;

[0046] S3: Select a three-layer composite seepage-proof sleeve. The sleeve is integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer. The seepage-proof sleeve is coaxially nested into the inside of the steel wire mesh composite pipe port.

[0047] S4: Prepare a steel wire wetted molten material ring, a main anti-seepage molten material ring, and an outer protective molten material ring, and coaxially sleeve the three molten material rings on the end face of the pipe end in sequence;

[0048] S5: It adopts a double-step annular hot pressing mold, and the mold interior simultaneously extrudes three layers of molten material rings and the outer edge of the anti-seepage sleeve;

[0049] S6: After molding, the mold is not depressurized and is slowly cooled and solidified until the sleeve and end face fusion layer are completely set. After releasing the pressure, it is naturally cooled to room temperature.

[0050] In step S1, after cutting, a double-sided rotary sander is used for simultaneous processing. After sanding, high-pressure dry nitrogen is used to purge the debris from the end. In step S2, the inner wall heating temperature range is 60℃, the cross-section heating temperature range is 75℃, and the outer wall heating temperature range is 60℃. In step S2, the infrared heating time is controlled at 36s, and the heating range only covers a 20mm area at the pipe end. In step S3, the wall thickness of the anti-seepage sleeve is set to 1.6mm, the outer edge of the sleeve extends 2mm beyond the pipe end face, and the three-layer mass ratio of the sleeve is 70% tough PE layer, 22% anti-seepage modification layer, and 8% coupling fusion layer. In step S4, 1.3% silane coupling agent is added to the steel wire impregnation ring, and 2.6% antioxidant anti-seepage resin is added to the main anti-seepage ring. The overall total thickness of the three-layer molten ring is maintained at 1.3mm. In step S5, the mold temperature is controlled at 126℃, the molding pressure is 0.4MPa, and the holding time is 35s. The inner step of the mold presses against the outer edge of the anti-seepage sleeve, while the outer step simultaneously presses against the outer edge of the three-layer molten material ring. In step S6, the cooling rate is kept constant at 1.5℃ / min during the slow cooling stage. The mold clamping pressure is maintained throughout the process, and the pressure is released only after the multi-layer welded structure has completely solidified.

[0051] Example 4

[0052] This embodiment proposes a self-sealing multi-layer welding forming process for steel wire mesh composite pipes, including the following steps:

[0053] S1: Cut the steel wire mesh composite pipe and grind the end face and chamfer the inner and outer walls of the port of the steel wire mesh composite pipe;

[0054] S2: Zoned activation heating of the inner wall, cross-section, and outer wall of the steel wire mesh composite pipe port;

[0055] S3: Select a three-layer composite seepage-proof sleeve. The sleeve is integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer. The seepage-proof sleeve is coaxially nested into the inside of the steel wire mesh composite pipe port.

[0056] S4: Prepare a steel wire wetted molten material ring, a main anti-seepage molten material ring, and an outer protective molten material ring, and coaxially sleeve the three molten material rings on the end face of the pipe end in sequence;

[0057] S5: It adopts a double-step annular hot pressing mold, and the mold interior simultaneously extrudes three layers of molten material rings and the outer edge of the anti-seepage sleeve;

[0058] S6: After molding, the mold is not depressurized and is slowly cooled and solidified until the sleeve and end face fusion layer are completely set. After releasing the pressure, it is naturally cooled to room temperature.

[0059] In step S1, after cutting, a double-sided rotary sander is used for simultaneous processing. After sanding, high-pressure dry nitrogen is used to purge the debris from the end. In step S2, the inner wall heating temperature range is 62℃, the cross-section heating temperature range is 78℃, and the outer wall heating temperature range is 62℃. In step S2, the infrared heating time is controlled at 42s, and the heating range only covers a 25mm area at the pipe end. In step S3, the wall thickness of the anti-seepage sleeve is set to 1.6mm, the outer edge of the sleeve extends 3mm beyond the pipe end face, and the three-layer mass ratio of the sleeve is 70% tough PE layer, 22% anti-seepage modification layer, and 8% coupling fusion layer. In step S4, 1.4% silane coupling agent is added to the steel wire impregnation ring, and 2.8% antioxidant anti-seepage resin is added to the main anti-seepage ring. The overall total thickness of the three-layer molten ring is maintained at 1.5mm. In step S5, the mold temperature is controlled at 128℃, the molding pressure is 0.5MPa, and the holding time is 42s. The inner step of the mold presses against the outer edge of the anti-seepage sleeve, while the outer step simultaneously presses against the outer edge of the three-layer molten material ring. In step S6, the cooling rate is kept constant at 1.5℃ / min during the slow cooling stage. The mold clamping pressure is maintained throughout the process, and the pressure is released only after the multi-layer welded structure has completely solidified.

[0060] Example 5

[0061] This embodiment proposes a self-sealing multi-layer welding forming process for steel wire mesh composite pipes, including the following steps:

[0062] S1: Cut the steel wire mesh composite pipe and grind the end face and chamfer the inner and outer walls of the port of the steel wire mesh composite pipe;

[0063] S2: Zoned activation heating of the inner wall, cross-section, and outer wall of the steel wire mesh composite pipe port;

[0064] S3: Select a three-layer composite seepage-proof sleeve. The sleeve is integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer. The seepage-proof sleeve is coaxially nested into the inside of the steel wire mesh composite pipe port.

[0065] S4: Prepare a steel wire wetted molten material ring, a main anti-seepage molten material ring, and an outer protective molten material ring, and coaxially sleeve the three molten material rings on the end face of the pipe end in sequence;

[0066] S5: It adopts a double-step annular hot pressing mold, and the mold interior simultaneously extrudes three layers of molten material rings and the outer edge of the anti-seepage sleeve;

[0067] S6: After molding, the mold is not depressurized and is slowly cooled and solidified until the sleeve and end face fusion layer are completely set. After releasing the pressure, it is naturally cooled to room temperature.

[0068] In step S1, after cutting, a double-sided rotary sander is used for simultaneous processing. After sanding, high-pressure dry nitrogen is used to purge the debris from the end. In step S2, the inner wall heating temperature range is 65℃, the cross-section heating temperature range is 80℃, and the outer wall heating temperature range is 65℃. In step S2, the infrared heating time is controlled at 50s, and the heating range only covers a 30mm area at the pipe end. In step S3, the wall thickness of the anti-seepage sleeve is set to 1.8mm, the outer edge of the sleeve extends 3mm beyond the pipe end face, and the three-layer mass ratio of the sleeve is 70% tough PE layer, 22% anti-seepage modification layer, and 8% coupling fusion layer. In step S4, 1.5% silane coupling agent is added to the steel wire impregnation ring, and 3.0% antioxidant anti-seepage resin is added to the main anti-seepage ring. The overall total thickness of the three-layer molten ring is maintained at 1.6mm. In step S5, the mold temperature is controlled at 130℃, the molding pressure is 0.6MPa, and the holding time is 45s. The inner step of the mold presses against the outer edge of the anti-seepage sleeve, while the outer step simultaneously presses against the outer edge of the three-layer molten material ring. In step S6, the cooling rate is kept constant at 1.5℃ / min during the slow cooling stage. The mold clamping pressure is maintained throughout the process, and the pressure is released only after the multi-layer welded structure has completely solidified.

[0069] Examples 1-5 were used to test the self-sealing multi-layer fusion welding process of steel wire mesh composite pipes. The internal water seepage channels at the ends and the delamination phenomenon of the multi-layer fusion weld were detected. The results are shown in the table below:

[0070] Example 1 No internal wall seepage channels Non-layered peeling Example 2 No internal wall seepage channels Non-layered peeling Example 3 No internal wall seepage channels Non-layered peeling Example 4 No internal wall seepage channels Non-layered peeling Example 5 No internal wall seepage channels Non-layered peeling

[0071] As shown in the table above, the embedded anti-seepage sleeve and the three-layer end face molten material ring are fully melted and integrated, and there is no independent layer interface. As the preheating temperature, molding pressure, sleeve wall thickness and total thickness of molten material increase simultaneously, the filling density of the gaps in the steel wire cross-section by the molten material continues to increase.

[0072] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0073] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-sealing multi-layer welding forming process for steel wire mesh composite pipes, characterized in that, Includes the following steps: S1: Cut the steel wire mesh composite pipe and grind the end face and chamfer the inner and outer walls of the port of the steel wire mesh composite pipe; S2: Zoned activation heating of the inner wall, cross-section, and outer wall of the steel wire mesh composite pipe port; S3: Select a three-layer composite seepage-proof sleeve. The sleeve is integrally extruded from an inner tough PE layer, a middle seepage-proof modified layer, and an outer coupling fusion layer. The seepage-proof sleeve is coaxially nested into the inside of the steel wire mesh composite pipe port. S4: Prepare a steel wire wetted molten material ring, a main anti-seepage molten material ring, and an outer protective molten material ring, and coaxially sleeve the three molten material rings on the end face of the pipe end in sequence; S5: It adopts a double-step annular hot pressing mold, and the mold interior simultaneously extrudes three layers of molten material rings and the outer edge of the anti-seepage sleeve; S6: After molding, the mold is not depressurized and is slowly cooled and solidified until the sleeve and end face fusion layer are completely set. After releasing the pressure, it is naturally cooled to room temperature.

2. The self-sealing multi-layer welding forming process for steel wire mesh composite pipe according to claim 1, characterized in that: In step S1, after the cutting is completed, a double-sided rotary sand mill is used for synchronous processing. After the grinding is completed, high-pressure drying nitrogen is used to purge the debris from the port.

3. The self-sealing multi-layer welding forming process for steel wire mesh composite pipe according to claim 2, characterized in that: In step S2, the inner wall heating temperature range is 55-65℃, the cross-sectional heating temperature range is 70-80℃, and the outer wall heating temperature range is 55-65℃.

4. The self-sealing multi-layer welding forming process for steel wire mesh composite pipe according to claim 3, characterized in that: In step S2, the infrared heating time is controlled between 25 and 50 seconds, and the heating range only covers a 10-30 mm area at the pipe end.

5. The self-sealing multi-layer welding forming process for steel wire mesh composite pipe according to claim 4, characterized in that: In step S3, the wall thickness of the anti-seepage sleeve is set to 1.2-1.8mm, the outer edge of the sleeve extends 2-3mm beyond the end face of the pipe, and the mass ratio of the three layers of the sleeve is 70% tough PE layer, 22% anti-seepage modified layer, and 8% coupling fusion layer.

6. The self-sealing multi-layer welding forming process for steel wire mesh composite pipe according to claim 5, characterized in that: In step S4, 1.0%-1.5% silane coupling agent is added to the steel wire impregnation ring, and 2.0%-3.0% antioxidant anti-seepage resin is added to the main anti-seepage ring. The overall total thickness of the three-layer molten ring is maintained at 0.9-1.6mm.

7. The self-sealing multi-layer welding forming process for steel wire mesh composite pipe according to claim 6, characterized in that: In step S5, the mold constant temperature is controlled at 122-130℃, the molding pressure is 0.3-0.6MPa, the holding time is 20-45s, the inner step of the mold extrudes the outer edge of the anti-seepage sleeve, and the outer step simultaneously presses the outer edge of the three-layer molten material ring.

8. The self-sealing multi-layer welding forming process for steel wire mesh composite pipe according to claim 7, characterized in that: In step S6, the cooling rate is kept constant at 1.5℃ / min during the slow cooling stage, and the mold clamping pressure is maintained throughout the process. The pressure is released after the multi-layer welded structure has been completely cured.