KR20000061120A - manufacturing method for hydraulic cylinder of sea water and method detecting of absolute position - Google Patents

Abstract

PURPOSE: A method for manufacturing a hydraulic cylinder for seawater and a displacement detection method thereof are provided to expand the life span of a piston rod of the hydraulic cylinder by forming a ceramic coated layer and a chrome plated layer continuously for preventing corrosion of the piston rod due to the seawater, thereby improving the reliability of the piston rod displacement detected by sensors. CONSTITUTION: A method for manufacturing a hydraulic cylinder for seawater includes the steps of forming spiral grooves in a peripheral direction with a predetermined distance along an outer periphery of a piston rod having a predetermined diameter(S10), coating the outer periphery of the piston rod including the spiral grooves with ceramic by rotating the piston rod to be anti-corrosive(S20), evaporating chemical copper on the ceramic-coated surface to have a chemical affinity with chrome(S30), plating chrome on the surface evaporated with the chemical copper with a predetermined thickness(S40), and carrying out honing of the piston rod with a predetermined thickness for continuously forming a ceramic coated layer on the outer periphery of the piston rod and a chrome plated layer on a surface of the spiral grooves of the piston rod(50).

Description

Manufacturing method for hydraulic cylinder of sea water and method detecting of absolute position

The present invention relates to a method for manufacturing a hydraulic cylinder for seawater and an absolute position detection method, and more particularly, to coat the piston rod outer periphery of the hydraulic cylinder as ceramic and chromium layers so as to have corrosion resistance to a working environment such as seawater. The present invention relates to a method for manufacturing a hydraulic cylinder for seawater and an absolute position detection method.

In general, heavy construction equipment such as excavators are equipped with hydraulic cylinders for driving work devices such as booms, arms and buckets, respectively, within a predetermined stroke range. In addition, such heavy construction equipment has been steadily developed and used to automate the operation of the work device to perform the same work repeatedly and continuously without depending on the skill of the operator depending on the working conditions.

In order to automate the operation of such work tools, it is necessary to accurately detect the absolute position of these work tools as well as information on the position of the work tools, that is, the relative positions of the booms, arms and buckets.

However, the heavy construction equipment such as excavators mainly work in places where the working environment is extremely poor due to the characteristics of the equipment, so that the piston rod of the hydraulic cylinder driving the work equipment is directly exposed to the environment such as sea water. Corrosion is remarkably reduced and service life is greatly reduced. Due to this, there is a problem that the management and maintenance costs of the construction equipment due to frequent replacement of the corresponding parts are increased.

In addition, when the outer circumferential surface of the piston rod described above is directly exposed to an environment such as seawater, corrosion resistance is easily degraded and damaged by vibration and shock. This causes a problem that the accuracy of the detection value detected by the detection sensor mounted at the predetermined position to detect the displacement of the piston rod is lowered.

Accordingly, an object of the present invention, the ceramic rod and the outer periphery of the piston rod of the hydraulic cylinder for driving the work device of the heavy construction equipment mainly working in an environment of extremely poor working conditions due to the characteristics of the equipment, such as ceramic and The coating process as a chromium layer greatly improves the service life thereof, thereby providing a method of manufacturing a hydraulic cylinder for seawater that can significantly reduce the cost of managing and maintaining the construction equipment.

Another object of the present invention is to prevent the outer circumferential surface of the piston rod of the hydraulic cylinder driving the work device of the heavy construction equipment from being corroded from the working environment such as seawater, thereby improving the reliability of the detection value of the corresponding sensor for detecting displacement of the piston rod. It is to provide an absolute position detection method of a hydraulic cylinder for seawater that can be greatly improved.

1 is a view for explaining the working process of the manufacturing method of the hydraulic cylinder for seawater according to the present invention,

(a) is a diagram showing the formation of a spiral groove in the outer periphery of the piston rod,

(b) is a view showing coating the ceramic powder along the spiral groove by using a plasma jet,

(c) shows the plating of chromium on the surface of the ceramic coating layer,

(d) is a diagram showing that the ceramic coating layer and the chromium plating layer are formed repeatedly and continuously on the outer periphery of the piston rod.

2 is a flow chart showing a manufacturing process of the hydraulic cylinder for seawater according to the present invention,

3 is a block diagram of an absolute position detecting circuit for a stroke of a cylinder applied to an absolute position detecting method using an absolute position detecting cylinder rod according to the present invention;

4 is a flow chart of the absolute position detection method using the cylinder rod for absolute position detection according to the present invention,

FIG. 5 is a principle waveform diagram illustrating generation of a square wave and a triangular wave during forward movement of a cylinder during the process of FIG. 4;

6 is a principle waveform diagram showing generation of a square wave and a triangular wave during the reverse movement of the cylinder during the process of FIG. 4;

7 is a principle waveform diagram illustrating restoration of a square wave and a triangular wave in the process of FIG. 4;

8 is a principle waveform diagram showing a method of calculating an absolute position with respect to the stroke of a cylinder.

* Explanation of symbols used in the main part of the drawing

2; Piston rod

3; Spiral groove

4; Plasma jet

5; Ceramic coating layer

6; Chrome plated layer

An object of the present invention described above, the first step of forming a helical groove in the circumferential direction at a predetermined interval along the outer circumference of the piston rod of a predetermined diameter, and the piston rod so that the piston rod has corrosion resistance against seawater A second step of coating a ceramic rod on the outer circumference of the piston rod including the helical groove while rotating, a third step of depositing chemical copper on the surface of the ceramic coating layer to have chemical affinity with chromium, and the surface on which the chemical copper is deposited A fourth step of plating chromium at a predetermined thickness, and a ceramic coating layer is formed on the outer periphery of the piston rod, and a chromium plating layer is formed on the helical groove surface to repeatedly form the ceramic coating layer and the chromium plating layer on the surface of the piston rod. And a fifth step of honing the piston rod at a predetermined thickness as much as possible. It is achieved by providing a method of manufacturing a hydraulic cylinder for seawater.

According to a preferred embodiment, the plating layer thickness of chromium plated by the fourth step is 55 to 65μm.

According to a preferred embodiment, the predetermined interval of the spiral groove formed in the piston rod outer periphery by the first step is characterized in that 1 to 1.5mm.

The object of the present invention described above is to form a plurality of magnetic scales processed by irregularities at predetermined equal intervals on one side of the cylinder rod, and to detect a magnetic field change of the portion by a pair of magnetic sensors having different phases, and thus microcomputer and 1 / N division. A method for detecting a direction of a cylinder rod and a position detection for a stroke of a cylinder for detecting a shifted displacement amount by performing signal processing using a counter and counting the processed signal, comprising: a first process of driving a cylinder; Acquiring the output voltage of the magnetic sensor unit according to the cylinder driving in the first step, and comparing the phase of the square wave generated in the second tablet with the second step of sequentially generating a pair of square waves and triangle waves; The third process of determining the direction of the stroke of the cylinder and the phase of the triangular wave generated in the second process by comparing the absolute position point by the iron machining A fourth process of determining two successive values; and a fifth process of counting the number of square waves between two absolute position points when the absolute position points due to iron machining are two consecutive as a result of the determination of the fourth process; A sixth step of replacing the absolute position value stored with the current position value according to the results of steps 3 and 5, and a period of the regular regular unevenness interval of the triangular wave generated in the second step after performing the sixth step; The seventh step of restoring the normal waveform equal to and restoring the square wave of the same period from the restored triangular wave and calculating and storing the absolute position value of the cylinder rod by signal processing the counted triangular wave and the square wave restored in the seventh step. It is achieved by providing an absolute position detection method of the hydraulic cylinder for sea water, characterized in that controlled by the eighth process.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are intended to explain in detail the understanding of the technical contents according to the present invention, and thus the technical scope of the present invention is not limited.

1 and 2, the manufacturing method of the hydraulic cylinder for sea water according to the present invention will be described.

By using a bite 1 of a predetermined shape, a spiral groove 3 along the outer circumferential surface of the piston rod 2 of a predetermined diameter is spaced 1 to 1,5 mm and a predetermined depth in the circumferential direction of the piston rod 2. (See first step S10).

A ceramic jet is placed on the outer circumferential surface of the piston rod 2 including a spiral groove 3 while rotating the piston rod 2 such that the piston rod 2 has corrosion resistance against seawater; 4) it is heated and melted and coated as a predetermined thickness t1 (see second step S20).

Chemical copper is deposited on the surface of the ceramic coating layer 5 of the piston rod 2 by chemical vapor deposition so as to have a chemical affinity with hard chromium (see third step S30).

Chromium is plated on the surface on which the chemical copper is deposited as a predetermined thickness t2 (see fourth step S40).

The ceramic coating layer 5 is formed on the outer circumference of the piston rod 2 and the chrome plating layer 6 is formed on the surface of the spiral groove 3 so that the ceramic coating layer 5 and the chromium are formed on the outer circumference of the piston rod 2. The piston rod 2 is honed at a predetermined thickness so that the plating layer 6 can be formed repeatedly and continuously (see a fifth step S50).

At this time, preferably, the plating layer thickness t2 of the chromium plated by the fourth step S40 is 60 μm, and the spiral groove formed on the outer circumference of the piston rod 2 by the first step S10 ( The predetermined interval in 3) is 1 mm.

Therefore, the piston rod 2 has a strong corrosion resistance against seawater by the ceramic coating layer 5 coated on the outer circumference of the piston rod 2 as a predetermined thickness t1, so that the service life of the piston rod 2 is increased. It can be greatly extended.

Further, the piston rod 2 is vibrated and impacted by a hard chromium plated layer 6 plated with a predetermined thickness t2 on the surface of the spiral groove 3 formed at predetermined intervals on the outer periphery of the piston rod 2. It can be prevented from being damaged and damaged from.

On the other hand, as shown in Figures 3 to 8, the absolute position detection method of the hydraulic cylinder for sea water according to the present invention will be described as follows.

The cylinder driving unit 210 driven in response to the input of the cylinder driving signal drives the second hydraulic cylinder 280, and the magnetic sensor unit 230 mounted on the second hydraulic cylinder 280 detects a magnetic field change of the magnetic scale. To apply an output signal to the second microcomputer 270.

The second microcomputer 270 exchanges necessary information with the storage device 250 provided therein or separately, and also sends and receives signals with the 1 / N division counter 260 to the stroke of the cylinder including signal processing. It controls the overall operation of the absolute position detection circuit.

As shown in FIG. 4, a series of control is performed by the first microcomputer 270, and a process of driving a cylinder (S610) and an output voltage of the magnetic sensor unit according to the cylinder driving are obtained, and a pair therefrom. The step of generating the square wave and the triangular wave of (S620) and the step of comparing the phase of the generated square wave to determine the direction for the stroke of the cylinder (S630), and compares the phase of the generated triangular wave by iron processing A process of determining whether two absolute position points are continuous (S640), a process of counting the number of square waves between two absolute position points (S650) when the absolute position points are continuous by iron processing, and the determined cylinder The process of replacing the stored absolute position value with the current position value according to the direction of the stroke and the number of square waves between the counted two absolute position points (S660) and used to determine the absolute position point Restoring the angular wave to the same normal waveform as the period of the original norm interval, restoring the square wave of the same period from the restored triangular wave (S670), and processing and counting the restored triangular wave and square wave by signal processing. The process of calculating and storing the absolute position value of S680 is controlled in order.

The cylinder driver 210 drives the second cylinder 280 in response to the input of the cylinder driving signal by the driver (S610). At this time, the magnetic field change in the magnetic scale operated on the rod of the second cylinder 280 Is detected by a magnetic sensor 231 such as a pair of Hall sensors having different phases provided in the magnetic sensor unit 230, and then outputs an output voltage to the signal processor 232.

The signal processor 232 converts the detected signal from the pair of sine wave magnetic sensors 231 into a signal that can be recognized by the second microcomputer 270 and amplifies and filters the second signal. 270) (S621).

The second microcomputer 270 converts the analog signal from the signal processor 232 into a digital signal using an analog / digital converter therein and then converts a sine wave signal into a pair of square waves using a pulse conversion algorithm. In step S622, the converted square wave is generated again using a triangular wave generation algorithm to generate a triangular wave having the same period (S623).

As shown in FIG. 5, in the forward movement of the cylinder, a pair of square waves have two values of +5 [V] and 0 [V], which are driving voltage levels of the second microcomputer 270, and the two magnetic sensors Due to the arrangement, the phase difference is 90 °, and the period is doubled in the iron part. In addition, since the distance between the magnetic sensors is larger than the period of the magnetic scale, the shape of the two square waves at the portion where the magnetic scale is removed is also different.

The triangular wave generated by the square wave in the portion where the self-diameter is removed is squared as the rising edge of the square wave, that is, when it becomes 0 [V] to +5 [V], the square wave is maintained at +5 [V]. Accumulate a predetermined value for each sampling time, and when the falling edge of the square wave, i.e., from +5 [V] to 0 [V], the size is set to 0 again and the square wave maintains 0 [V] for each sampling time. It is generated by accumulating negative values.

At this time, the sampling time can be shortened according to the degree of the desired absolute position value, and the reference potential of the triangular wave formation is set to +2.5 [V] for convenience.

As shown in FIG. 6, the same principle as that described in FIG. 5 is generated except that the phase speed between the two waveforms is changed. That is, due to the position of the magnetic sensor 231 at the time of forward conveyance and the reverse conveyance of the cylinder, the phase is 90 degrees, and either waveform is generated first.

In addition, in the iron-processed portion, the generated triangular wave is about -3 times larger than that of the normal triangular wave.

After the square wave and the triangular wave are generated by the second microcomputer 270 (S620), the moving direction of the cylinder rod may be determined by comparing the phases of the generated pair of square waves (S630), as shown in FIG. 5. As shown in FIG. 6, when the B phase is fast, the cylinder rod is stretched in the forward direction. As shown in FIG. 6, when the A phase is fast, the cylinder rod is contracted in the reverse direction.

In addition, by using the triangular wave generated by the second microcomputer 270 to determine whether two absolute position points due to yaw processing is continuous (S640), the absolute position point is the size of the peak value using the peak value of the triangular wave Compared with the peak value of the unevenly processed portion, the point is a predetermined multiple, that is, -3 times, which is illustrated in FIGS. 5 and 6.

According to the conveying direction of the cylinder rod of the present invention, there are a plurality of absolute position points, the absolute position value corresponding to each absolute position point is stored in the storage device (250).

As a result of the determination, if two absolute position points are consecutive, the number of square waves between the two determined absolute position points is counted (S650), and the absolute absolute value stored in correspondence with the counted direction and the conveying direction of the cylinder rod is determined in advance. Replace with the current position value for the displacement of the cylinder rod (S660).

Subsequently, the second microcomputer 270 uses the 1 / N division counter 260 to generate the original triangular wave generated in the process S623 to have a normal peak value of the triangular wave at the absolute position to count the displacement. The waveform is restored to the same waveform as that of the regular interval between irregularities (S671), and then the square wave is restored again (S670).

As shown in FIG. 7, after reconstructing the triangular wave generated in the process S623 to a triangular wave corresponding to the regular regular unevenness interval (S671) to count the final displacement of the cylinder rod, The square wave of the same period must be restored (S672) and input to the 1 / N division counter 260.

Principle of restoration of triangle wave for this purpose is to increase the peak value of triangular wave at the part without one self-calibration to be between 0 times to make triangle wave between predetermined times than the peak value of normal triangle wave, for example, between -1.1 times and -2 times, From -2.1 to -3 times, the triangle wave is restored by decreasing it back to zero.

The position value of the current cylinder rod, which is the absolute displacement amount of the cylinder rod, is calculated from the pair of square waves and triangle waves restored as described above (S680).

As shown in Fig. 8, the principle of calculating the absolute position with respect to the stroke of the cylinder is calculated by counting the restored square wave by dividing 1 / N, and the current triangular wave value as the peak value of the triangular wave one cycle ago. It calculates by summing up the exact position calculated by dividing, which will be described based on the 1/4 division counter in the present invention.

The 1 / N division counter 2 O divides the square wave received by the second microcomputer 270 into 1/4.

At this time, the reason for dividing the detected pulse signal by 1 / N is to increase the detection accuracy by N times, and the N value is determined according to the desired precision.

The second microcomputer 270 calculates the jaw position for the cylinder stroke that is four times more accurate than the magnetic scale by counting the number of pulses of the square wave divided into quarters and is stored in the memory device 250.

After calculating the jaw position, the restored triangular wave is used to calculate the position value more precise than quarter division, and the exact position value can be obtained by dividing the current triangular wave value by the peak value of the triangular wave one cycle ago. Store in device 250.

At this time, it should be noted that if the exact position value is larger than the position value of the quarter cycle, the position value of the quarter cycle should be subtracted, because of the quarter cycle through the 1 / N division counter 260. This is because the position value is calculated.

For example, if one period of the magnetic scale is 2 [mm], a quarter counting counter is used to make a positioning coefficient having an accuracy of 0.5 [mm], and the exact positioning coefficient is more precise than the positioning coefficient using the exact positioning coefficient algorithm. Perform

At this time, if the exact position value is larger than 0.5 [mm], 0.5 [mm] is subtracted because it is calculated by a quarter dispensing counter.

Therefore, the final position value is obtained by summing the values of the coarse position and the correct position stored in the storage device 250, and this value is stored in the storage device 250 by the absolute current of the cylinder rod relative to the stroke of the cylinder. It is stored as a position value, and in some cases it is output to the display unit of the not shown.

As described above, according to a preferred embodiment, the outer periphery of the piston rod of the hydraulic cylinder for driving the work device of the heavy construction equipment mainly for working in an environment with extremely poor working conditions due to the characteristics of the equipment, the corrosion resistance against the working environment such as seawater Coating with ceramic and chromium layers to significantly increase its service life, thereby significantly reducing the cost of managing and maintaining heavy construction equipment.

In addition, since the outer circumferential surface of the piston rod of the hydraulic cylinder driving the working device of the heavy construction equipment is prevented from being corroded from the working environment such as seawater, the reliability of the detection value of the corresponding sensor detecting the displacement of the piston rod can be greatly improved. do.

Claims (4)

A first step of forming a helical groove in a circumferential direction at a predetermined interval along an outer circumference of a piston rod having a predetermined diameter; A second step of coating the piston rod outer circumference including the helical groove with ceramic while rotating the piston rod such that the piston rod has corrosion resistance against seawater; Depositing chemical copper on the surface of the ceramic coating layer to have a chemical affinity with chromium; A fourth step of plating chromium on the surface on which the chemical copper is deposited as a predetermined thickness; And A ceramic coating layer is formed on the outer periphery of the piston rod, and a chromium plating layer is formed on the helical groove surface to hounch the piston rod at a predetermined thickness so that the ceramic coating layer and the chromium plating layer are repeatedly formed on the surface of the piston rod. Method of manufacturing a hydraulic cylinder for sea water, characterized in that it comprises a fifth step. The method of manufacturing a hydraulic cylinder for seawater according to claim 1, wherein the plating layer of the chromium plated by the fourth step has a thickness of 55 to 65 m. The method of claim 1, wherein a predetermined interval between the spiral grooves formed on the piston rod outer circumference by the first step is 1 to 1,5 mm. A plurality of magnetic scales with uneven processing are formed on one side of the cylinder rod at predetermined equal intervals, and a pair of magnetic sensors having different phases detect magnetic field changes of the portion, and then signal processing and processing using a microcomputer and a 1 / N division counter. In the method for detecting the position of the cylinder stroke by detecting the direction of displacement of the cylinder rod and the shifted displacement amount by performing a coefficient on the signal: First process of driving the cylinder: A second process of acquiring an output voltage of the magnetic sensor unit according to the cylinder driving in the first process, and sequentially generating a pair of square waves and triangle waves; A third step of determining a direction of the stroke of the cylinder by comparing the phases of the square waves generated in the second step; A fourth step of determining whether two absolute position points by iron processing are consecutive by comparing the phases of the triangular waves generated in the second step; A fifth step of counting the number of square waves between the two absolute position points when the determination result of the fourth process is two consecutive absolute position points by iron machining; A sixth step of replacing the stored absolute position value with the current position value according to the results of the third and fifth processes; A seventh step of restoring the triangular wave generated in the second step to a normal waveform identical to the period of the regular regular unevenness interval after performing the sixth step, and restoring a square wave of the same period from the restored triangular wave; And And an eighth step of calculating and storing an absolute position value of the cylinder rod by signal processing and counting the triangular wave and the square wave restored in the seventh step.