CN101675213B - Ram bop position sensor - Google Patents

Abstract

A kind of method for determining wellhead component motion, including：The relative position of wellhead component is sensed in selected time interval with magnetostrictive sensor.This method includes sending the signal from magnetostrictive sensor to data acquisition equipment, and relative to selected time interval with the relative position of data acquisition equipment record wellhead component.In addition, this method includes the position of the wellhead component of record compares with operational data to determine whether relative position is desired.

Description

Ram blowout preventer position sensor

technical field

Embodiments disclosed herein relate generally to instrumentation of ram blowout preventers. More specifically, embodiments disclosed herein relate to the direct measurement of the position, velocity and rate of motion of a ram in a ram blowout preventer.

Background technique

Well control is an important aspect of oil and gas exploration. For example, when drilling wells, safety equipment must be put in place to prevent injury to personnel and damage to equipment due to accidents associated with drilling activities.

The drilling process involves penetrating various subterranean geological formations, or "layers." Sometimes the wellbore penetrates to form a zone at a pressure substantially higher than the wellbore maintains pressure. When this happens, the well is said to have a "kick". The flow of the formed fluid (which may be a liquid, a gas, or a mixture of both) into the wellbore typically causes a pressure buildup with an accompanying kick. The higher pressure kick propagates from the entry point of the wellbore up the wellbore (from the high pressure area to the low pressure area). If the kick is allowed to travel to the surface, drilling fluid, well tools and other drilling equipment can be ejected out of the wellbore. Such "blowouts" can cause serious damage to drilling equipment (including, for example, drilling rigs) or cause casualties to drilling personnel.

Because of the risk of blowouts, devices known as blowout preventers are installed above the wellheads of surface or deepwater drilling installations in order to effectively seal the wellbore until effective measures can be taken to control the kick. The blowout preventers can be activated so that the kick is sufficiently contained and "circulated out" from the system. There are several types of BOPs, the most commonly used of which are ram BOPs and annular BOPs (including spherical BOPs).

A ram blowout preventer typically has a body and at least one pair of horizontally opposed shrouds. The cover is usually secured to the body by, for example, bolts around its periphery. Alternatively, the cover can be hinged and bolted to the body so that the cover can be turned to the side for maintenance. Inside each cover is a piston-actuated gate. The rams can be tubular rams (when actuated, move to engage and enclose the drill pipe and tools to seal the borehole), or shear rams (when actuated, move to engage with the wellbore any drill pipe or well tool joint and physically shears it). Or a fully enclosed ram (when starting, it closes the well hole like a gate valve). The rams are typically positioned relative to each other, whether tubular rams, shear rams or fully enclosed rams, and the rams typically seal against each other near the center of the borehole to completely seal the borehole.

The gate is generally constructed of steel and is provided with resilient members on the sealing surface. Ram blocks are available in various configurations that allow them to seal the wellbore. Tubular rams typically have a circular opening in the middle corresponding to the diameter of the pipe in the bore, thereby sealing the well when the pipe is in the bore; however, these tubular rams can only effectively seal a limited range of pipe diameters. Variable well rams are designed to seal a wider range of pipe diameters. Various ram blocks are also interchangeable within the BOP to allow the well operator to optimize the BOP configuration for a particular hole section or job in progress. Examples of ram blowout preventers are disclosed in US Patent Nos. 6,554,247, 6,244,560, 5,897,094, 5,655,745, and 4,647,002, each of which is incorporated herein by reference in its entirety.

Knowing the well condition is very important to keep the well working and to predict problems that will occur. With these parameters, the well can be more effectively monitored so that a safe condition can be maintained. In addition, when an unsafe condition is detected, the well can be manually or automatically initiated to shut down in good time. For example, pressure and temperature sensors within a blowout preventer cavity can indicate or predict unsafe conditions. These and other signals are displayed as control signals on a console used by the well operator. For example, the well operator can affect the condition of the well by adjusting the rotational speed of the drill pipe, the downward pressure on the drill bit and the circulation pump of the drilling fluid. Furthermore, when it is desired to close the BOP rams, it is useful for the operator to know exactly where each ram is.

One device that has been used in the past to signal the relative position of components located in a closed enclosure (not necessarily a blowout preventer casing) is a potentiometer type sensor. Such devices employ one or more sensors that are subject to wear and are inaccurate in harsh environments. Also, such sensors are easily lifted from surfaces whether tracked or not, which leads to unreadiness. Also, loss of power often results in distorted readings, as these devices operate to incrementally add or subtract particular revolutions or wire section related values to previous values. Also, devices such as these are notoriously poor high speed devices. Therefore, potentiometric measurements are not useful for accurately determining the positional parameters of the gate movement. Also, potentiometer sensors are not suitable for high speed applications, so potentiometer sensors are rarely or never used in gate monitoring applications.

In addition, incremental measurement devices that only measure intermediate movements have the inherent disadvantage of having to reset to baseline when a power failure occurs, and the inaccuracy that accompanies continuous measurement.

To improve the accuracy of measuring the position of the gate, magnetostrictive sensors are used to monitor and/or control the position of the gate. As described in US Patent Nos. 5,320,325 and 5,407,172, which are incorporated by reference, the piston drive arm of the shutter is placed parallel to the fixed magnetizable waveguide. A magnet assembly surrounds the waveguide and is attached to a carriage arm attached to the piston tail.

In US Patent Nos. 7,023,199, 7,121,185 and 6,509,733, the magnetostrictive sensor is mounted in the internal opening of the sensor port. The sensor has a pressure tube that extends into the lumen of the piston body and is telescopically received in the rod channel of the piston and rod assembly.

In each of the above patents, the positioning of the magnetostrictive sensor is not optimal. For example, in US Patent No. 7,023,199, because the sensor extends into the cavity of the cylinder, maintenance on the sensor unit must require the gate to be inoperative. Although not into the cavity of the cylinder block, the attachment of the sensor and the bracket arm using US Patent No. 5,320,325 can result in inaccurate measurements of the ram position and can increase the manufacturing cost of the ram BOP.

Accordingly, the present invention is characterized by providing an improved apparatus for accurately measuring the positioning or position of a blowout preventer ram or ram piston.

Accordingly, there is a need for an improved apparatus for accurately measuring the positioning or position of a blowout preventer ram or ram piston.

Contents of the invention

In one aspect, the present disclosure relates to a method of monitoring cylinder pressure applied to a blowout preventer ram, the method comprising: sensing the relative position of the blowout preventer ram with a magnetostrictive sensor; The signal of the telescopic sensor is sent to the data acquisition device; the cylinder pressure applied to the gate plate is sensed with the pressure sensing device; the signal from the pressure sensing device is sent to the data acquisition device; and the data acquisition device records The sensed cylinder pressure as a function of the sensed relative position.

In another aspect, the present disclosure relates to a method of testing components of a blowout preventer, the method including performing a cyclic test on the blowout preventer; Cylinder pressure; and the magnetostrictive sensor senses and records the gate position during the cycle test.

In another aspect, the present disclosure relates to a method of determining movement of a wellhead, the method comprising sensing the relative position of the wellhead with a magnetostrictive sensor; sending a signal from the magnetostrictive sensor to a data an acquisition device; recording the relative position of the wellhead member with the data acquisition device relative to the selected time interval; and comparing the recorded position of the wellhead member with the operational data to determine whether the relative position is desired.

In another aspect, the present disclosure relates to a ram type BOP comprising a body; a vertical hole passing through the body; a horizontal hole passing through the body intersecting the vertical hole; a pair of ram assemblies, wherein the ram assemblies are adapted for controlled horizontal movement into and out of the vertical bore, wherein each ram assembly includes a hydraulic piston connected at a first end to the ram block, connected at the second end to the piston tail; a magnetostrictive waveguide extending into a hole in the at least one piston tail; a permanent magnet placed on the at least one piston tail; the magnetostrictive waveguide including wires to receive the An interrogation pulse of the sensor, wherein the interrogation pulse generates a helical return signal in response to the relative position of the permanent magnet with respect to the waveguide; wherein the sensor is configured to receive the helical return signal and output a ram block position corresponding to the at least one piston tail.

In another aspect, the present disclosure relates to a method of determining the relative position of a ram, the method comprising interengaging a magnetostrictive waveguide in a bore at the tail of a piston; longitudinally magnetizing the waveguide with at least one permanent magnet secured to the tail of the piston part of the waveguide; pulse the wire located inside the waveguide to generate a hoop magnetic field, wherein a return signal is generated when the hoop magnetic field meets the longitudinally magnetized portion of the waveguide; and determine the relative position of the shutter from the return signal.

In another aspect, the present disclosure relates to a method of instrumenting a ram blowout preventer, the method comprising removing a head seal; removing a piston tail from a hydraulic ram piston; installing a replacement piston tail, the replacing The piston tail of the piston includes a hole; installing a replacement head closure including an instrument port; attaching a magnet assembly to the piston tail; and disposing the magnetostrictive sensor from the replacement head closure components such that the magnetostrictive sensor is configured to engage and disengage the piston aft bore as the hydraulic ram piston reciprocates.

Other aspects and advantages of the invention will become apparent from the following description and appended claims.

Description of drawings

Fig. 1 shows a partial sectional view of a ram blowout preventer in the prior art.

2 is a cross-sectional view of a ram blowout preventer cover assembly according to embodiments disclosed herein.

3 is a detailed view of a portion of the ram blowout preventer cover assembly of FIG. 2 .

FIG. 4 depicts a graph showing cylinder pressure as a function of ram clearance, according to an embodiment of the present disclosure.

detailed description

In one aspect, embodiments disclosed herein relate to a ram blowout preventer including instrumentation for determining a position of a ram within the blowout preventer. In another aspect, embodiments disclosed herein relate to methods for determining the position, velocity, or closure rate of a ram in a ram blowout preventer.

FIG. 1 shows a ram type blowout preventer 10 . The well tubular 12 is shown passing through the central vertical hole 14 of the body 16 of the blowout preventer 10. The well tubular 12 may be part of the drill string at the top of the well being drilled or the production string of a well under oil or gas production. part. Body 16 may include opposing horizontal channels 18 transverse to bore 14 . The horizontal channel may extend outwardly to a cover 17 connected to the body 16 . Working in channels 18 are rams 20 driven by hydraulic pistons 22 in respective cylinder casings 23 located in respective hydraulic cylinder blocks 19 to which cover 17 is connected outwardly. Piston 22 may reciprocate ram 20 back and forth in horizontal channel 18 to open or close packer or wear pad 24 on the face of ram 20 relative to the surface of tubing 12 . Hydraulic fluid connections (not shown) work together with the opening chamber 25 and closing chamber 26 to position the gate 20 .

As shown, the ram BOP 10 may include an aft portion 28 connected to the piston 22 . Tail 28 of piston 22 reciprocates within cylinder head 30 , which may be bolted or otherwise connected to cylinder block 19 .

As mentioned above, it is desirable to know the position of the gate 20 or to position the gate 20 . This can be achieved by positioning the magnetostrictive sensor components within the hydraulic cylinder head enclosure (which is connected to the cylinder block 19 shown in Figure 1). Those skilled in the art will recognize that the embodiments disclosed herein are broadly applicable to any ram-type blowout preventer, and even more generally to any device employing rams.

2 and 3 illustrate a cylinder head and sensor setup according to embodiments disclosed herein. The cylinder head 30 may be connected to the cylinder block 19 by screwing, welding, flanged or any other connection known in the art. The piston 22 (shown in its fully open position) is connectable to a piston tail 28 having a piston tail bore 32 extending at least partially therethrough. The magnet assembly 38 may be concentric with the piston tail 28 and attached to the piston tail 28 by a screw 40 (a non-magnetic screw in some embodiments). A gasket 42 , such as an O-ring, may be placed between the magnet assembly 38 and the piston tail 28 .

Magnet assembly 38 may include two or more permanent magnets. In some embodiments, the magnet assembly 38 includes three magnets; in other embodiments, it includes four magnets, and in still other embodiments, it may include more than four magnets.

A fixed waveguide 44 may be located within the cylinder head 30 and may extend at least partially into the piston tail bore 32 of the piston tail 28 . Preferably, the piston tail 28 is radially spaced from the waveguide 44 so as not to interfere with the movement of the piston 22 or cause wear on the waveguide 44 . Similarly, magnet assembly 38 may be radially spaced from waveguide 44 . In selected embodiments, the magnets of magnet assembly 38 may lie in a plane transverse to waveguide 44 .

Additionally, a conductive element or wire (not shown) may be positioned through the center of waveguide 44 . The wires and waveguide may be connected to a sensor 46 external to the cylinder head 30 through a communication port 48 . The sensor 46 may also include suitable means for sending an interrogating current pulse to the wire.

O-rings located between the cylinder head 30 and the cylinder block 19 seal against leakage. O-rings may also be used to seal the connection between communication port 48 and sensor 46 .

As the ram 20 moves axially, the piston tail 28 and magnet assembly 38 move axially by the same amount. Thus, the position of the shutter 20 can be determined on a continuous basis through the operation of a magnetostrictive sensor disposed therein.

Regarding the operation of magnetostrictive sensors, magnetostriction refers to the fact that some metals, such as iron or nickel or iron-nickel alloys, expand or contract when placed in a magnetic field. The magnetostrictive waveguide 44 may have a longitudinally magnetized region within the outer magnet assembly 38 when the magnet assembly 38 translates longitudinally with respect to the waveguide 44 . As noted above, the magnet assembly 38 includes permanent magnets that may be located at spaced, evenly spaced locations in a plane transverse to the waveguide 44 and equally spaced radially with respect to the surface of the waveguide 44 . The magnet assembly 38 generates an external magnetic field that longitudinally magnetizes a region of the waveguide 44 .

The waveguide 44 surrounds a wire (not shown) positioned along its axis. The wire may be periodically pulsed or interrogated with a current in a manner well known in the art, such as by a sensor 46 located on the outside of the enclosure 30 . This current creates a toroidal magnetic field around the wire and waveguide 44 . When the hoop magnetic field intersects the magnetic field generated by the magnet assembly 38 , a helical magnetic field is sensed in the waveguide 44 , resulting in acoustic pulses propagating toward both ends of the waveguide 44 . A suitable damper (not shown) at the end of the waveguide 44 prevents echo reverberation of the pulses from occurring. However, at the sensor end or head, the helicon wave is converted into a waveguide twist that applies transverse stress to the very thin magnetostrictive strip connected to the waveguide 44 . A phenomenon known as the Villari effect causes the flux linkage of the magnets passing through the sensing coil to be disturbed by the propagating stress wave on the strip and generate a voltage across the coil. Sensor 46 may also boost this voltage for metering or control purposes.

Because electrical current pulses travel at close to the speed of light, while acoustic pulses travel only roughly at the speed of sound, there is a time gap between the moment each pulse is received by the head-end sensor compared to when the electrical pulse is generated by the head-end electronics. This time interval is a function of the distance of the outer magnet assembly 38 from the sensor end of the tube. By carefully measuring the time interval and dividing by the propagation velocity of the tube, the absolute distance of the magnet assembly from the head end of the tube can be determined.

In the event of a loss of signal, no information is lost and therefore no readings need to be re-zeroed or re-reset. The reading is determined entirely by the position of the magnet assembly 38 relative to the sensor 46 .

By knowing the absolute position of the ram, it can be determined whether the ram is fully closed, whether the ram is lifted, how worn the packers or wear pads in front of the ram are, and how much backlash or How worn is it. By successive interrogation pulses, the closing rate or velocity of the piston can be measured, as well as the rate of movement or acceleration and deceleration of the piston.

As used herein, "ram clearance" refers to the translational gap between horizontally opposed rams of a blowout preventer. In selected embodiments, the ram clearance can be calculated and recorded by determining the absolute position of each ram (thus allowing the relative distance between the rams to be calculated). In selected embodiments, the BOP ram position may be determined using a cylinder and sensor setup similar to that shown in FIGS. 2 and 3 , or using any other instrumentation mechanism known in the art. Additionally, the relative position of the rams can be sent to a data acquisition device that can be used to calculate and record the BOP ram clearances. In selected embodiments, ram clearance may be quantified by a measured or calculated separation distance (eg, inches, centimeters, etc.) between two rams.

Additionally, as used herein, "cylinder pressure" refers to the hydraulic pressure applied to the piston configured to close the blowout preventer ram. In this way, cylinder pressure values can be measured and recorded at various locations (for example, at different ram clearances). As such, a blowout preventer according to embodiments disclosed herein may include a pressure sensor or any other device configured to sense cylinder pressure. Additionally, the pressure sensing device may send a signal to the data acquisition device to record cylinder pressure at selected locations.

Alternatively, a force sensor can be used to give and record the actual ram force as a function of cylinder pressure. For purposes of this disclosure, cylinder pressure and ram force are used interchangeably because ram force can be defined as cylinder pressure times the cross-sectional area of the ram piston.

Referring now to 4, there is shown a graph showing cylinder pressure as a function of ram clearance in accordance with an embodiment of the present disclosure. The data shown in Figure 4 were observed when the BOP ram sheared cables and pipes of various shapes and sizes. This data can be measured and recorded using any of the equipment and methods previously described. Data points and curves are included in the graph and are helpful in understanding the surrounding conditions around the object closing the gate.

The curves are composed of data points observed when the BOP ram shears various cables and pipes. Curve 100 shows the data observed when shearing a shear sub (Shear Sub) with a new "ram block", where the ram block is the part attached to the ram configured to shear Objects extending through a blowout preventer. Similarly, curve 200 shows data observed when a shear joint is sheared with a used ram block. Curve 300 depicts data observed when shearing 5.5 inch thick wall pipe and curve 500 depicts data observed when shearing 3.5 inch pipe and cable with BOP. Finally, curve 600 shows the data observed when only the cable is sheared with the BOP.

Additionally, the data points reflected by the graph may represent certain events occurring as the BOP ram closes around the object. In particular, data point 401 represents the location at which cylinder pressure begins to exceed operator close pressure after contact with an object. Also as shown, data points 402 in the graph may represent cylinder pressures required to shear pipes and/or cables through the blowout preventer. Additionally, data points 402 may represent the position of the ram when the pipe and/or cable was sheared. As used herein, "shear pressure" is the value of cylinder pressure required to initiate shearing of tubing and/or cable. Data point 403 may represent the location where the shutter contacts a flexible element (eg, a seal). Data points 404 may represent the position and cylinder pressure when the rams are in contact with each other. Data point 405 may represent increasing cylinder pressure from the time the ram and seal contact, thereby implying that the ram is fully closed.

In one embodiment, a blowout preventer may include a cylinder, ram, and sensor setup similar to that shown in FIGS. 2 and 3 . BOPs can be cycle tested by opening and closing the rams multiple times. A cycle may include fully opening and closing the gate once. Cyclic testing is a method known in the art that can be used to assess the reliability of a tested component. As the BOP is cycled, data including cylinder pressure at selected locations (ie, ram clearances) may be measured and recorded during each cycle. This data can then be compiled to show how BOP components (eg, seals, packers, wear plates, and locking mechanisms) react or move during the cycle. This data can be used to determine when parts need to be replaced or rebuilt. Reasons for replacing BOP components may include, but are not limited to, excessive recoil and wear.

Other wellhead components in the industry are subject to prolonged motion. Wellhead components may include, for example, wellhead connectors, fail-safe valves, pod wedges, diverter locks, stack-mounted accumulation bottles, and any other components known in the art. In one embodiment, sensor equipment including magnetostrictive sensors may be used to determine the position of at least one wellhead member. The magnetostrictive sensor may send a signal to a data acquisition device, which may then record the position of the at least one wellhead member. The magnetostrictive sensor may send a plurality of signals to the data acquisition device at selected time intervals, thereby indicating any movement of the wellhead member during the selected time intervals.

There is also a need to add instrumentation to the existing ram BOP. To add instrumentation to an existing ram BOP, only a portion of the ram BOP can be replaced or retrofitted, reducing the cost required to upgrade existing equipment to include instrumentation. For example, it is possible to instrument an existing ram BOP by replacing or retrofitting only the head closure and piston tail.

Existing cylinder head closures and piston tails can be removed. The removed piston tail can be retrofitted with a center hole for the instrumentation and reattached to the hydraulic piston, or a new piston tail with a center hole that can be attached to the hydraulic piston. Likewise, the head closure may be retrofitted to include instrumentation ports, or a new head closure with instrumentation ports connectable to the ram BOP body. A magnet assembly may be attached to a piston tail having a central bore, and as described above, a magnetostrictive sensor may be at least partially disposed within the central bore of the piston tail.

After adding the instrumentation, the magnetostrictive sensor needs to be calibrated to the fully open and fully closed positions of the gate. Additionally, the instrumentation for determining the position of the ram can be operatively connected to the digital control system. This digital control system can then be used to monitor, display and/or control the position of the shutter based on electrical signals from the magnetostrictive sensors.

Advantageously, embodiments disclosed herein may provide an easily installed instrumentation for a ram blowout preventer that can accurately measure the position, velocity and acceleration of the ram. Additionally, the embodiments disclosed herein do not enter the hydraulic cylinder cavity, which may provide additional advantages.

Furthermore, embodiments disclosed herein may allow for flexibility in ram blowout preventer components while providing consistent construction of the ram blowout preventer. For example, a customer may want a ram BOP with or without instrumentation. The integrity of the rod connecting the ram to the piston is not compromised by the presence of the bore in which the sensor is placed (the sensor is placed in the bore in the rod), so rods are not required with or without the instrument Enhance or transform. Additionally, the heads and tails provided with the instrument are easily interchangeable with those that do not provide instrument ports. In this way, components are interchangeable, existing ram BOPs can be easily retrofitted to include instrumentation, and consumers will have flexibility in product selection without fear of inconsistent manufacturing.

Embodiments disclosed herein may advantageously provide methods for testing and monitoring blowout preventer components, thereby detecting and/or preventing potential problems or issues in operation. For example, embodiments disclosed herein may provide a method of sensing backlash in a locking mechanism of a gate. Additionally, embodiments disclosed herein may provide a method of testing and measuring the service life and/or maintenance intervals of certain components (eg, seals, packers, locking mechanisms) included in a blowout preventer. Additionally, embodiments disclosed herein may provide a method of detecting wear and/or interference hazards before or during operation of a blowout preventer.

Additionally, embodiments disclosed herein may advantageously provide a method and apparatus for recording closed position over time to graphically estimate remaining life for rubber components. Additionally, embodiments disclosed herein may provide apparatus and methods for monitoring the position of BOP components during sealing and testing to determine how elastomeric seals function and react so that elastomeric design can be improved. Additionally, embodiments disclosed herein may provide methods and apparatus for determining when a tube is sheared by a ram blowout preventer, thereby affecting the accumulator demand.

Furthermore, embodiments disclosed herein may be used for the movement of pistons in annular blowout preventers. Such an embodiment may include the use of position indicators to determine replacement intervals for wear plates and containment units for annular blowout preventers. Additionally, embodiments disclosed herein may be used to stack components including, but not limited to, wellhead connectors, fail-safe valves, pod wedges, diverter locks, and accumulator bottles.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art having the benefit of this disclosure will recognize that other embodiments can be devised without departing from the scope of the invention disclosed herein. Accordingly, the scope of the invention should be limited only by the appended claims.

Claims (12)

1. a kind of ram blowout preventer, including：

Body；

Through the vertical holes of the body；

The lateral aperture through the body intersected with the vertical holes；

A pair of flashboard assemblies being placed on the opposite side of the body in lateral aperture, wherein the flashboard assembly is suitable to controllably To the vertical holes and from the vertical holes, controllably horizontal movement goes out for horizontal movement, wherein each flashboard assembly includes hydraulic pressure Piston, the hydraulic piston is connected to ram blocks in first end, and piston tail is connected at the second end；

A pair of cylinder caps, it is configured to attach to the body and receives corresponding piston tail；

Magnetostrictive waveguide pipe, the first end of the magnetostrictive waveguide pipe is attached to one of the pair of cylinder cap, the mangneto Second end of telescopic waveguide pipe is independent and extends to be formed in the hole of at least one piston tail, and the hole is formed in institute State inside at least one piston tail；

The permanent magnet being placed at least one described piston tail；And

The magnetostrictive waveguide pipe includes wire to receive the interrogation pulse from sensor, wherein the interrogation pulse is responded In the permanent magnet helical return signal is produced on the relative position of the waveguide；

Wherein described sensor is configured to receive the helical return signal and export to correspond at least one described piston tail part The ram blocks position in portion.

2. ram blowout preventer according to claim 1, it is characterised in that the magnetostrictive waveguide pipe is by longitudinal flux Change.

3. ram blowout preventer according to claim 1, it is characterised in that the interrogation pulse produces ring around wire Magnetic field.

4. ram blowout preventer according to claim 3, it is characterised in that the helical return signal is in response to the ring Produced to the interaction of magnetic field and the longitudinal magnetized area of the waveguide.

5. a kind of method for the relative position for determining flashboard, methods described includes：

The magnetostrictive waveguide that is bonded with each other in the hole of piston tail pipe, the hole is formed in the inside of the piston tail；

Utilize the part fixed to waveguide described at least one permanent magnet longitudinal magnetization in the piston tail；

It is pointed to the wire on the inside of the waveguide and imposes pulse to produce toroidal magnetic field, wherein when the toroidal magnetic field runs into institute Return signal is produced when stating waveguide longitudinal magnetization part；

The relative position of the flashboard is determined from the return signal.

6. method according to claim 5, further comprises：The return signal is sensed over a time period to determine State the speed of flashboard.

7. method according to claim 6, further comprises：Determine the closing rate of the flashboard.

8. a kind of increase the method for instrument to ram preventer, methods described includes：

Remove cylinder head enclosure；

Piston tail is removed from hydraulic ram piston；

The piston tail changed is installed, the piston tail of the replacing includes the hole formed in it；

The cylinder head enclosure changed is installed, the cylinder head enclosure of the replacing includes instrument port；

Magnet assembly is attached in the piston tail；And

Arrange the magnetostrictive sensor of the cylinder head enclosure from the replacing so that the magnetostrictive sensor is configured Moved back and forth into the hydraulic ram piston so as to engaging and depart from the piston tail bore.

9. method according to claim 8, further comprises：The magnetostrictive sensor is calibrated to indicate the flashboard Fully open position and the flashboard fully closed position.

10. method according to claim 8, further comprises：

The magnetostrictive sensor is operably connected to numerical control system；With

The position of the flashboard is determined using the magnetostrictive sensor.

11. method according to claim 10, further comprises：Based on the electric signal from the magnetostrictive sensor Show the position of the flashboard.

12. method according to claim 10, further comprises：Based on the electric signal from the magnetostrictive sensor Control the position of the flashboard.