A hydraulic elevator latch trigger device and a hydraulic elevator latch

Abstract

The present invention discloses a hydraulic elevator trigger device and a hydraulic elevator, belonging to the technical field of oil drilling, including: a bushing for positioning the drill string; a spool assembly installed on the elevator for controlling the on-off of the hydraulic oil circuit of the elevator; a pushing mechanism installed on the elevator for cooperating with the bushing to push the spool assembly to perform linear motion; wherein, the pushing mechanism includes a moving pin A and a moving pin B, the moving pin B is fixedly connected to the moving pin A, both the moving pin A and the moving pin B are slidably engaged with a limiting chute opened on the elevator, a pushing groove for pushing the spool assembly is opened on the moving pin B, and further includes: an elastic pressing assembly installed on the elevator for elastically pressing the moving pin A to make the moving pin A abut against the side parts of the two bushings; the present invention makes the operation of the elevator to hold the drill string more safe, convenient, efficient and reliable.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil drilling, and particularly relates to a hydraulic elevator latch trigger device and a hydraulic elevator latch. Background Art

[0002] An elevator latch is an essential tool for oil drilling operations. During drilling operations, the elevator latch must be used to lift and lower the pipe string. Currently, most of the elevator latch devices used on-site rely on manual judgment to determine whether the pipe string is in place and manually operate the closing action of the elevator latch. After various drill strings are placed in the elevator latch, the operator subjectively judges whether the drill string is in place and then performs subsequent operations such as closing the elevator latch. Such an operation mode is prone to human misjudgment, resulting in various failures when clamping the drill string. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a hydraulic elevator latch trigger device and a hydraulic elevator latch, which solve the above problems.

[0004] To achieve the above objectives, the present invention is realized through the following technical solutions: A hydraulic elevator latch trigger device includes two bushings symmetrically and rotatably connected to the elevator latch through a bushing rotating shaft, and further includes:

[0005] A spool valve assembly, installed on the elevator latch, for handling the on / off of the hydraulic oil circuit of the elevator latch;

[0006] A pushing mechanism, installed on the elevator latch, for cooperating with the bushing to push the spool valve assembly, including an elastic pressing assembly installed on the elevator latch. The elastic pressing assembly includes a spring positioning block, and the spring positioning block sleeved with a spring adjusting pad is embedded and installed at the notch opened on the limit sliding groove of the elevator latch and is detachably connected to the elevator latch. A moving pin B fixedly connected with a moving pin A is slidably arranged in the limit sliding groove. One end of a return spring B installed in the limit sliding groove is fixedly connected to the end of the moving pin B, and the other end is sleeved on the spring positioning block and abuts against the end face of the spring adjusting pad;

[0007] A spring adjusting pad replacement alarm system, for determining the thickness of the spring adjusting pad and giving a warning, including:

[0008] A thickness adjustment coefficient determination module, which generates a thickness adjustment coefficient based on the current length information of the return spring B, the current thickness information of the spring adjusting pad, and the ambient temperature information of the return spring B;

[0009] A judgment module, for constructing a coefficient safety model and inputting the thickness adjustment coefficient into the coefficient safety model to output a safety coefficient, comparing the obtained safety coefficient with a safety coefficient threshold. If the obtained safety coefficient is greater than the safety coefficient threshold, it outputs a judgment information and an alarm information that the spring adjusting pad needs to be replaced;

[0010] The thickness determination module generates the thickness information of the spring adjustment pad to be replaced based on the judgment information, the thickness adjustment coefficient, and the current thickness information of the return spring B.

[0011] Based on the above technical solutions, the present invention also provides the following alternative technical solutions:

[0012] Further technical solution: The spool assembly includes a spool and a spool push rod. The spool is fixedly connected to the upper end of the spool push rod. A rubber sleeve plug B and a rubber sleeve plug A are fixedly connected to the spool in sequence. The spool push rod is slidably matched with a valve barrel fixedly connected to a lifting clamp. The rubber sleeve plug B is slidably matched with the valve barrel. An oil circuit connector for connecting a hydraulic oil pipe is provided on the valve barrel. A return spring A fixedly connected to the inner wall of the valve barrel is fixedly connected to the spool. The lower end of the spool push rod is located in a push groove and has a round head.

[0013] Further technical solution: A push groove for pushing the spool assembly is provided on the moving pin B.

[0014] Further technical solution: The spring adjustment pad replacement alarm system further includes:

[0015] A data acquisition module for collecting the state information of the spring positioning block, the pressing force information of the moving pin A against the adapter core, and the thickness information of the current spring adjustment pad. The state information includes the current length information of the return spring B and the temperature information of the environment where the return spring B is located.

[0016] Further technical solution: The specific steps of the thickness adjustment coefficient determination module are as follows:

[0017] S201. Construct a thickness adjustment coefficient determination model through the current length information of the return spring B, the thickness information of the current spring adjustment pad, the temperature of the environment where the return spring B is located, the target pressing force information, and the reference temperature information. The thickness adjustment coefficient determination model is expressed as:

[0018]

[0019] represents the thickness adjustment coefficient, represents the target pressing force information, represents the current pressing force information, represents the material thermal expansion coefficient, represents the current length information of the return spring B, represents the current environment temperature information, represents the reference temperature information, represents the thickness information of the current spring adjustment pad;

[0020] S202. Import the current length information of the return spring B, the thickness information of the current spring adjusting pad, and the ambient temperature where the return spring B is located into the thickness adjustment coefficient determination model to output the thickness adjustment coefficient.

[0021] Further technical solution: The reference temperature refers to the ambient temperature of the spring system in the designed or calibrated state. The coefficient of thermal expansion of the material refers to the change in the unit length of the material under a unit temperature change, which reflects the sensitivity of the material to temperature changes. The larger the value, the greater the expansion of the material when heated or the contraction when cooled.

[0022] Further technical solution: The coefficient safety model is expressed as: , where represents the safety factor, represents the thickness adjustment coefficient.

[0023] Further technical solution: The specific steps of the thickness determination module include:

[0024] S401. Construct a thickness determination model through the current length information of the return spring B, the thickness information of the current spring adjusting pad, the ambient temperature where the return spring B is located, the target pressing force information, and the reference temperature information. The thickness determination model is expressed as:

[0025]

[0026] represents the thickness information of the spring adjusting pad that needs to be replaced, represents the thickness adjustment coefficient, represents the target pressing force information, represents the current pressing force information, represents the coefficient of thermal expansion of the material, represents the current length information of the return spring B, represents the current ambient temperature information, represents the reference temperature information, represents the thickness information of the current spring adjusting pad, represents the thrust adjustment term, represents the temperature compensation term;

[0027] S402. Receive the judgment information formed by the judgment module, and import the thickness adjustment coefficient and the current thickness information of the spring adjusting pad into the thickness determination model to output the thickness information of the spring adjusting pad that needs to be replaced.

[0028] Further technical solution: A hydraulic elevator clamp adopts the above-mentioned hydraulic elevator clamp triggering device.

[0029] The present invention provides a hydraulic elevator trigger device and a hydraulic elevator, which have the following beneficial effects compared with the prior art:

[0030] 1. Through the linkage design of the bushing and the pushing mechanism, and combined with the automatic on-off control of the hydraulic oil circuit by the valve core assembly, the present invention realizes triggering and closing when the drill string arrives, without manual intervention, significantly reducing the risk of misjudgment and improving operation safety and work efficiency;

[0031] 2. In the present invention, the elastic pressing assembly dynamically compensates for the elastic force fluctuation caused by temperature change through the return spring B and the replaceable spring adjusting pad, ensuring stable operation of the device under different working conditions. And through the precise cooperation of the limit chute and the moving pin shaft, the system reliability is further enhanced;

[0032] 3. The present invention integrates an alarm system for replacing the spring adjusting pad, which collects data on the length of the return spring B, the ambient temperature and the pressing force in real time, calculates the safety factor through a mathematical model and gives an early warning, and prompts to replace the thickness of the adjusting pad in advance, reducing sudden failure shutdowns and extending the service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a three-dimensional structure schematic diagram of the present invention.

[0034] Figure 2 is a front view of the present invention.

[0035] Figure 3 is a right view of the present invention.

[0036] Figure 4 is a top view of the present invention.

[0037] Figure 5 is a structural schematic diagram of the valve core assembly of the present invention.

[0038] Annotation of reference numerals: 1. Bushing; 2. Bushing rotating shaft; 3. Valve core assembly; 301. Valve core; 302. Valve core push rod; 303. Rubber sleeve plug A; 304. Rubber sleeve plug B; 305. Valve barrel; 306. Oil circuit connector; 307. Return spring A; 4. Pushing mechanism; 401. Moving pin shaft A; 402. Moving pin shaft B; 403. Push groove; 404. Elastic pressing assembly; 4041. Spring positioning block; 4042. Spring adjusting pad; 4043. Return spring B; 5. Drill string. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] The following describes the specific implementation of the present invention in detail with reference to specific embodiments.

[0041] Please refer to Figures 1 to 5 , a hydraulic elevator latch trigger device provided by an embodiment of the present invention, comprising:

[0042] A bushing 1, two of the bushings 1 are symmetrically rotatably connected to the elevator latch through a bushing rotating shaft 2 for positioning the drill string 5:

[0043] A spool assembly 3, installed on the elevator latch for controlling the on / off of the hydraulic oil circuit of the elevator latch;

[0044] A pushing mechanism 4, installed on the elevator latch for cooperating with the bushing 1 to push the spool assembly 3 to perform a linear motion;

[0045] Among them, the pushing mechanism 4 includes a moving pin A 401 and a moving pin B 402. The moving pin B 402 is fixedly connected to the moving pin A 401. The moving pin A 401 and the moving pin B 402 are both slidably matched with a limiting chute (not marked in the figure) opened on the elevator latch. A pushing groove 403 for pushing the spool assembly 3 is opened on the moving pin B 402. It further includes:

[0046] An elastic pressing assembly 404, installed on the elevator latch for elastically pressing the moving pin A 401 to cause the moving pin A 401 to abut against the side parts of the two bushings 1;

[0047] Among them, the elastic pressing assembly 404 includes a spring positioning block 4041, a spring adjusting pad 4042 and a return spring B 4043. The spring adjusting pad 4042 is sleeved on the spring positioning block 4041. The spring positioning block 4041 is embedded at the notch of the limiting chute and is detachably connected to the elevator latch. The return spring B 4043 is installed in the limiting chute. One end of the return spring B 4043 is fixedly connected to the end of the moving pin B 402. The other end of the return spring B 4043 is sleeved on the spring positioning block 4041 and abuts against the end face of the spring adjusting pad 4042.

[0048] In the embodiment of the present invention, the drill string 5 is inserted into the elevator. At this time, the drill string 5 pushes the bushing 1 to rotate around the bushing shaft 2. At this time, the bushing 1 pushes the movable pin A401 to drive the movable pin B402 to slide along the limiting slide groove. At this time, the movable pin B402 squeezes the return spring B4043 to contract and resist the spring adjustment pad 4042. At this time, the push groove 403 provided on the movable pin B402 pushes the valve core assembly 3 to perform linear movement, thereby causing the valve core 301 in the valve core assembly 3 to move upward, thereby causing the liquid of the elevator to The hydraulic oil circuit is opened and subsequent actions are performed. If the valve core 301 does not move upward and the hydraulic oil circuit of the elevator is not opened, it means that the drill string 5 is not in the center of the core filling and the subsequent actions are not performed. When the drill string 5 is taken away, the reset spring B4043 pushes the movable pin B402 to drive the movable pin A401 to reset, and the valve core assembly 3 is also reset. At the same time, the elastic force of the reset spring B4043 can be adjusted by replacing the spring adjustment pad 4042 of different thicknesses to ensure the functional sensitivity of the entire hydraulic elevator trigger device.

[0049] Preferably, the valve core assembly 3 includes a valve core 301 and a valve core push rod 302, the valve core 301 is fixedly connected to the upper end of the valve core push rod 302, the valve core 301 is fixedly connected with a rubber sleeve plug B304 and a rubber sleeve plug A303 in sequence, the valve core push rod 302 is slidably matched with a valve cylinder 305 fixedly connected to the hanging card, the rubber sleeve plug B304 is slidably matched with the valve cylinder 305, the valve cylinder 305 is provided with an oil circuit connector 306 connected to the hydraulic oil pipe, the valve core 301 is fixedly connected with a reset spring A307 fixedly connected to the inner wall of the valve cylinder 305, the lower end of the valve core push rod 302 is located in the push groove 403 and is a round head, the purpose of this arrangement is The purpose is to utilize the pushing mechanism 4 to push the valve core push rod 302 to drive the valve core 301 to push the rubber sleeve plug B304 to slide along the valve cylinder 305, so as to cause the rubber sleeve plug B304 that blocks the inner oil port of the oil circuit connector 306 to move away from the inner oil port, thereby causing the two oil circuit connectors 306 to be connected with the inner cavity of the valve cylinder 305, thereby causing the hydraulic oil circuit connected to the oil circuit connector 306 to be connected, thereby realizing the opening of the hydraulic oil circuit, and further the pushing mechanism 4 is reset. At this time, the reset spring A307 pushes the valve core 301 to slide and reset with the rubber sleeve plug B304, thereby using the rubber sleeve plug B304 to block the inner oil port of the oil circuit connector 306, thereby realizing the disconnection of the hydraulic oil circuit.

[0050] As an embodiment of the present invention, it also includes: a spring adjustment pad replacement alarm system, which is used to determine the thickness of the spring adjustment pad 4042 and issue an alarm, including:

[0051] The data acquisition module is used to collect the status information of the spring positioning block 4041, the pressing force information of the moving pin A401 against the adapter bushing 1, and the thickness information of the current spring adjusting pad 4042. The status information includes the current length information of the return spring B4043 and the temperature information of the environment where the return spring B4043 is located.

[0052] The thickness adjustment coefficient determination module is used to construct a thickness adjustment coefficient determination model and import the current length information of the return spring B4043, the thickness information of the current spring adjusting pad 4042, and the environmental temperature information of the return spring B4043 collected by the data acquisition module into the thickness adjustment coefficient determination model to output the thickness adjustment coefficient.

[0053] The judgment module is used to construct a coefficient safety model and input the thickness adjustment coefficient into the coefficient safety model to output the safety coefficient, and compare the obtained safety coefficient with the safety coefficient threshold. If the obtained safety coefficient is greater than the safety coefficient threshold, it outputs the judgment information that the spring adjusting pad 4042 needs to be replaced and the alarm information.

[0054] The thickness determination module is used to construct a thickness determination model and import the thickness adjustment coefficient and the current thickness information of the return spring B4043 into the thickness determination model according to the judgment information of the judgment module to output the thickness information of the spring adjusting pad 4042 that needs to be replaced.

[0055] The specific working steps of the thickness adjustment coefficient determination module are as follows:

[0056] S201. Construct a thickness adjustment coefficient determination model through the current length information of the return spring B4043, the thickness information of the current spring adjusting pad 4042, the environmental temperature of the return spring B4043, the target pressing force information, and the reference temperature information. The thickness adjustment coefficient determination model is expressed as:

[0057]

[0058] represents the thickness adjustment coefficient, represents the target pressing force information, represents the current pressing force information, represents the material thermal expansion coefficient, represents the current length information of the return spring B4043, represents the current environmental temperature information, represents the reference temperature information, Indicates the thickness information of the current spring adjusting pad 4042. The reference temperature refers to the ambient temperature of the spring system in the designed or calibrated state. The coefficient of thermal expansion of the material refers to the change in the unit length of the material under a unit temperature change, reflecting the sensitivity of the material to temperature changes. The larger the value, the greater the expansion of the material when heated or the contraction when cooled.

[0059] S202. Import the current length information of the return spring B4043, the thickness information of the current spring adjusting pad 4042, and the ambient temperature where the return spring B4043 is located, which are collected by the data acquisition module, into the thickness adjustment coefficient determination model to output the thickness adjustment coefficient.

[0060] Among them, the coefficient safety model is expressed as:

[0061]

[0062] Among them, represents the safety factor, represents the thickness adjustment coefficient.

[0063] Among them, the specific working steps of the thickness determination module include:

[0064] S401. Construct a thickness determination model through the current length information of the return spring B4043, the thickness information of the current spring adjusting pad 4042, the ambient temperature where the return spring B4043 is located, the target abutting pressure information, and the reference temperature information. The thickness determination model is expressed as:

[0065]

[0066] represents the thickness information of the spring adjusting pad 4042 that needs to be replaced, represents the thickness adjustment coefficient, represents the target abutting pressure information, represents the current abutting pressure information, represents the coefficient of thermal expansion of the material, represents the current length information of the return spring B4043, represents the current ambient temperature information, represents the reference temperature information, represents the thickness information of the current spring adjusting pad 4042, represents the thrust adjustment term, represents the temperature compensation term;

[0067] S402. Receive the judgment information formed by the judgment module, and import the thickness adjustment coefficient and the current thickness information of the spring adjusting pad 4042 into the thickness determination model to output the thickness information of the spring adjusting pad 4042 that needs to be replaced.

[0068] Preferably, the current length information and current temperature information of the reset spring B4043 are measured by a distance sensor and a temperature sensor mounted on the moving pin B402 respectively. The pressing force of the moving pin A401 against the adapter 1 is measured by a pressure sensor located at the connection of the moving pin B402 and the push groove 403 (or a pressure sensor located at the contact end of the moving pin A401 and the adapter 1).

[0069] In the embodiments of the present invention, traditional maintenance relies on manual regular inspections or repairs after failures. However, the spring adjustment pad replacement alarm system, through real-time data monitoring and intelligent analysis, transforms the maintenance mode from "passive response" to "active prevention", significantly reducing the risk of sudden failures. By giving early warnings of the need for spring adjustment pad replacement, it reduces unplanned downtime, ensures production continuity, and through dynamic compensation for environmental changes, ensures the stability and sensitivity of the hydraulic elevator latch trigger device under different working conditions, avoiding potential safety hazards such as out-of-control hydraulic oil circuits and failure of the drill string clamping caused by spring failure.

[0070] A hydraulic elevator latch adopts the above-mentioned hydraulic elevator latch trigger device.

[0071] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusively, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0072] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydraulic elevating bowl trigger device, comprising two elevating bowls (1) symmetrically and rotatably connected to an elevating bowl through a union swivel (2), characterized in that, It also includes: A valve core assembly (3), installed on the elevating sub, for handling the on / off of the hydraulic oil circuit of the elevating sub; A pushing mechanism (4), installed on the elevating sub, for cooperating with the nipple (1) to push the valve core assembly (3), including an elastic pressing assembly (404) installed on the elevating sub. The elastic pressing assembly (404) includes a spring positioning block (4041). The spring positioning block (4041) sleeved with a spring adjusting pad (4042) is embedded and installed at the notch opened on the limit sliding groove of the elevating sub and is detachably connected to the elevating sub. A moving pin B (402) fixedly connected with a moving pin A (401) is slidably arranged in the limit sliding groove. One end of a return spring B (4043) installed in the limit sliding groove is fixedly connected to the end of the moving pin B (402), and the other end is sleeved on the spring positioning block (4041) and abuts against the end face of the spring adjusting pad (4042); A spring adjusting pad replacement alarm system, for determining the thickness of the spring adjusting pad (4042) and giving an alarm, including: A thickness adjustment coefficient determination module, which generates a thickness adjustment coefficient based on the current length information of the return spring B (4043), the thickness information of the current spring adjusting pad (4042), and the ambient temperature information of the return spring B (4043); A judgment module, for constructing a coefficient safety model and inputting the thickness adjustment coefficient into the coefficient safety model to output a safety coefficient, comparing the obtained safety coefficient with the safety coefficient threshold. If the obtained safety coefficient is greater than the safety coefficient threshold, it outputs a judgment message and an alarm message indicating that the spring adjusting pad (4042) needs to be replaced; A thickness determination module, which generates the thickness information of the spring adjusting pad (4042) to be replaced based on the judgment message, the thickness adjustment coefficient, and the thickness information of the current spring adjusting pad (4042); A data acquisition module, for acquiring the state information of the spring positioning block (4041), the pressing force information of the moving pin A (401) on the nipple (1), and the thickness information of the current spring adjusting pad (4042). The state information includes the current length information of the return spring B (4043) and the ambient temperature information of the return spring B (4043); The specific steps of the thickness adjustment coefficient determination module are as follows: S201. Construct a thickness adjustment coefficient determination model through the current length information of the return spring B (4043), the thickness information of the current spring adjusting pad (4042), the ambient temperature information of the return spring B (4043), the target pressing force information, and the reference temperature information. The thickness adjustment coefficient determination model is expressed as: represents the thickness adjustment coefficient, represents the target pressing force information, represents the current pressing force information, represents the coefficient of thermal expansion of the material, represents the current length information of the return spring B (4043), represents the current ambient temperature information, represents the reference temperature information, represents the thickness information of the current spring adjusting pad (4042); S202. Import the current length information of the return spring B (4043), the thickness information of the current spring adjusting pad (4042), and the ambient temperature information of the return spring B (4043) collected by the data acquisition module into the thickness adjustment coefficient determination model to output the thickness adjustment coefficient.

2. The hydraulic elevator latch triggering device according to claim 1, characterized in that A push groove (403) for pushing the valve core assembly (3) is opened on the moving pin B (402).

3. The hydraulic elevator latch trigger device according to claim 2, characterized in that The spool assembly (3) includes a spool (301) and a spool push rod (302). The spool (301) is fixedly connected to the upper end of the spool push rod (302). A rubber sleeve plug B (304) and a rubber sleeve plug A (303) are fixedly connected to the spool (301) in sequence. The spool push rod (302) is in sliding fit with a valve barrel (305) fixedly connected to a lifting clamp. The rubber sleeve plug B (304) is in sliding fit with the valve barrel (305). An oil path connector (306) for connecting a hydraulic oil pipe is arranged on the valve barrel (305). A return spring A (307) fixedly connected to the inner wall of the valve barrel (305) is fixedly connected to the spool (301). The lower end of the spool push rod (302) is located in a push groove (403) and has a round head.

4. The hydraulic elevator latch triggering device according to claim 1, characterized in that, The reference temperature information refers to the ambient temperature of the spring system in the design or calibration state. The coefficient of thermal expansion of the material refers to the change in the unit length of the material under a unit temperature change, reflecting the sensitivity of the material to temperature changes. The larger the value, the greater the amplitude of thermal expansion or contraction of the material when heated or cooled.

5. The hydraulic elevator latch triggering device according to claim 1, characterized in that, The coefficient safety model is expressed as: , where represents the safety coefficient, represents the thickness adjustment coefficient.

6. The hydraulic elevator latch triggering device according to claim 1, wherein The specific steps of the thickness determination module include: S401. Construct a thickness determination model based on the current length information of the return spring B (4043), the thickness information of the current spring adjusting pad (4042), the ambient temperature information of the return spring B (4043), the target pressing force information, and the reference temperature information. The thickness determination model is expressed as: Indicates the thickness information of the spring adjustment pad (4042) that needs to be replaced, Indicates the thickness adjustment coefficient, Indicates the target contact pressure information, Indicates the current contact pressure information, Indicates the coefficient of thermal expansion of the material, Indicates the current length information of the return spring B (4043), Indicates the current ambient temperature information, Indicates the reference temperature information, Indicates the current thickness information of the spring adjustment pad (4042), Indicates the thrust adjustment term, Indicates the temperature compensation term; S402. Receive the judgment information formed by the judgment module, and import the thickness adjustment coefficient and the thickness information of the current spring adjusting pad (4042) into the thickness determination model to output the thickness information of the spring adjusting pad (4042) that needs to be replaced.

7. A hydraulic elevating bail, characterized in that, Adopt the hydraulic lifting clamp trigger device according to any one of claims 1-6.

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