JPH0829545B2 - Automatic control method of tension jack for prestressed construction - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic control method for a tension jack for prestressed construction, more specifically, it can ensure accuracy of load control, can cope with malfunction of a computer, etc. The present invention relates to an automatic control method capable of easily dealing with additional tension and not causing plasticization of PC steel.

[Prior Art] Conventionally, in the tensioning work of PC steel, tensioning work is one of the important processes for introducing a predetermined tensioning force into the concrete structure and sufficiently exerting the performance of the prestressed concrete structure.

However, in this tension work, a specialized engineer uses his intuition and experience to open and close the hydraulic valve, measures the load with a pressure meter, measures the elongation with a scale, and checks it while writing it on the management graph and checking it step by step. It is the current situation that the load is increased to a predetermined load. In this way,
Since the final management is a check after tension work, it is not possible to reflect the value of group management in individual tension work, and there is a possibility that mistakes will occur because the creation of the management graph is manual, so tension while writing the management graph To proceed with the work,
There was a problem that it took time and that the number of workers (including the tension management graph creator) was large.

Therefore, in order to solve the above problems, due to the soaring labor costs of specialist workers and severe tension management centered on PC containment vessels at nuclear power plants, which has become a particular problem in recent years, automatic tension / automatic management using a computer Is about to be introduced. The pre-stressed tension technology by such automatic tension / automatic management is still in an early stage, and it is not the case that a complete systemization has been achieved. Only an easy-to-develop automatic management system is used, and tension (hydraulic jack operation) is At present, it depends on manual operation. It may be possible to install a large-scale computer to enable automatic tension / automatic management online, but the size of the device will increase and cost will increase, making it easy and quick for workers in the field who do not have specialized knowledge. There is a drawback that you cannot work.

Therefore, the inventors of the present invention previously disclosed in Japanese Patent Application No. 61-186526 can perform prestressed tension at low cost without requiring a large-scale device and without requiring a specialist.
The automatic control technology of PC steel tension was proposed.

The present inventors have obtained the following findings as a result of continuing their research in order to further improve the previously proposed technique.

That is, in the previously proposed technology, the tension load (holding point load) control is based on the load value (converted from an electric signal) from the pressure cell (device that measures the oil pressure) installed at the hydraulic discharge port. The computer judges whether or not the pressure has reached, and if it has reached, the solenoid valve installed at the hydraulic discharge port is closed to fix. If not, further hydraulic pressure is automatically sent to the hydraulic jack and the load value is measured again in the pressure cell and compared with the detent point load. Then, a method is adopted in which this operation is repeated by automatic control of a computer until the load at the holding point is reached.

However, in the method according to this previous proposal, there is a risk of introducing more tension than necessary into the PC steel material due to a malfunction of the computer, etc.In addition, the reaction speed is generally slow only by combining the solenoid valve and the computer, so the load increases. When the speed is fast (the shorter the cable is, the faster), it may be difficult to stop the hydraulic pressure discharge with a predetermined load, and the accuracy of the load control may not be ensured.

Therefore, it is conceivable to use a relief valve for the hydraulic pump unit, which has the operating characteristics shown in FIG. 9, that is, the operating characteristics in which the increase in hydraulic pressure stops suddenly when a predetermined tension load is reached.

However, when such a relief valve is used, the tension load is determined by the set value of the relief valve, so the setting of the relief valve is important for tension, and the setting itself is complicated.

OBJECT OF THE INVENTION Therefore, an object of the present invention is to provide an automatic control method of a tension jack for prestressed construction which does not require a large-scale device and does not require a professional engineer and can perform prestressed tension at low cost. Especially.

Another object of the present invention is to provide an automatic control method for a tension jack for prestressed construction, which can secure the accuracy of load control, can cope with malfunctions of a computer and the like, and which does not have the complexity of setting the relief valve itself. is there.

[Means for Solving the Problems] The present invention has been achieved as a result of intensive studies to achieve the above object.

That is, the automatic control method of the tension jack for prestressed construction according to the present invention is to set the hydraulic jack on the PC steel material arranged at a predetermined position, and to supply the hydraulic pressure to the hydraulic jack from the hydraulic pump unit with a relief valve. When applying a predetermined tension to the PC steel material, a microcomputer device is installed at the tension site, and tension management information including at least a control limit value is input to the microcomputer device,
Then, after introducing automatically measured tension data and measurement data of the stroke movement amount of the hydraulic jack, the microcomputer device makes a comparison judgment with the control limit value, and then a tension control signal is sent to the hydraulic pump unit. In the automatic control method of controlling the tension force by transmitting the operation characteristic of the relief valve to a predetermined tension load of 5
It is characterized in that the pressure increase is gradually suppressed from a low load of -30% before, and a predetermined tension load is managed and controlled by the microcomputer using the operating characteristics as a guideline.

In the present invention, “setting a hydraulic jack on a PC steel material arranged at a predetermined position” means that a PC steel material (including an unbonded PC steel wire) is attached to a grip or the like provided under the hydraulic jack.
Is to fix.

“Installing a microcomputer device at a tension site” means that the microcomputer device is installed at or near the site where the hydraulic jack is set (for example, a site office). There is a method to send a tension control signal to the hydraulic system by inputting measurement data by inputting measurement data to the hydraulic system, and also to the hydraulic system. There are a method of controlling the amount of oil from the hydraulic pump and a method of controlling the amount of oil by operating a solenoid valve or the like provided in the hydraulic pressure supply pipe.

There is also a method of incorporating microcomputer equipment directly into the hydraulic system. There are a method of directly incorporating into the hydraulic system, a method of incorporating into the hydraulic pump, and a method of incorporating into the supply pipe.

"Entering tension management information including at least a control limit value in a microcomputer device" means inputting tension control information including a control limit value for P-δ management or µ management. Here, P-δ control is control by the load indication (prestressed amount) of the jack at the time of tension and elongation of PC steel, and μ control is set by controlling the control limit by the friction coefficient between PC steel and sheath. Say that.

Although "input the data of tension measured automatically" differs depending on the management method, for example, in the case of P-δ management, the load reading (prestressed amount) of the jack and the elongation of PC steel during tension are automatically measured. Is to enter.

In the present invention, "operating characteristics of the relief valve" means
It means that the pressure-time history is on a constant curve, and the present invention provides the operating characteristics of this relief valve 5 to 30% before a predetermined tension load (holding point load), preferably about 10% before. One of the features is that the pressure is gradually increased from a low load. That is, if it is less than 5%, it becomes difficult to control the relief valve because it reaches the holding point load immediately, while if it exceeds 30%, it takes time to reach the holding point load, which is not practical.

The operating characteristics of the relief valve used in the present invention are limited as described above before reaching a predetermined tension load, but are not limited when the load is exceeded. That is, the final load control is performed by a computer, and the relief valve is used to suppress the load rising speed near the final load. Therefore, the relief valve is not required to be set with high accuracy (it can be arbitrarily set between A and B as shown in FIG. 5).

In the present invention, the microcomputer controls the opening and closing of the solenoid valve, and manages and controls along the guideline until the load at the stopping point is reached. As used herein, the term “guideline” refers to a curve represented by the operating characteristics of the relief valve up to a predetermined tension load. Therefore, even if the microcomputer malfunctions, the load does not exceed this guideline, so it does not become overtension (except when the manual setting of the relief valve is wrong). Then, when the load at the stopping point is reached, the solenoid valve is closed, and thereafter the fixing is performed so that the tension force is not released.

[Embodiment] An example of an apparatus for carrying out the control method of the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 1 is a hydraulic jack having a stroke of 1A.
The PC steel material grip (not shown) is moved according to the reciprocating movement (left and right movement in the drawing) of the PC steel material to which the one end is fixed.

An oil supply pipe 2 and an oil discharge pipe 3 are connected to the hydraulic jack 1. In addition, the hydraulic jack 1 has ON / OFF for starting.
A switch and a switch for tension stop are attached.
4 is a hydraulic pump unit. 5 is a personal computer with an input keyboard and a display (hereinafter,
A personal computer) and a control system 6 (which may have a printer (not shown)). Reference numeral 7 is a measuring device for a pressure converter and a solenoid valve, which will be described later, 8 is a data insertion portion such as a prestressed amount and an elongation amount of a PC steel material. It may be installed as a shield in the circuit board of No. 4 or may be installed externally.

Reference numeral 9 is a pressure converter, 10 is a solenoid valve (with a switch circuit and a driving device), and 10A is a relief valve.
The solenoid valve 10 and the relief valve 10A are incorporated in the hydraulic pump unit 4. The opening / closing of the solenoid valve 10 and the control of the opening / closing time are performed by the personal computer through the control system 6.

11 is a displacement meter, and the displacement meter 11 may be any as long as it can measure the amount of stroke in and out, for example, an electric type or potentiometer type displacement meter can be used, and an optical stroke detection device (submitted on the same date) Patent application relating to the above, “Title of Invention; Automatic Tension Jack Control Method for Prestressed Work”) can be used. Reference numeral 12 is a control cable, which is used here to transmit a solenoid valve opening / closing signal from the computer 5.

In the present invention, the above device is unitized into a second
A compact device as shown can be obtained.

In FIG. 2, the hydraulic pump unit 4 includes a hydraulic pump, an oil tank 41, a hydraulic hose connector 42 and the like.

Reference numeral 60 denotes a control device provided on the upper part of the hydraulic pump unit 4, and includes a personal computer, a control system, a measuring device, a microcomputer device such as a data insertion unit, and the like.

It is also preferable that a caster 43 be attached below the hydraulic pump unit 4 so that the device unit including the hydraulic pump unit 4 and the control device 60 can be moved.

The hydraulic jack 1 is connected to the oil supply pipe 2 and the oil discharge pipe 3, and the hydraulic jack 1 may be provided with a hand switch.

Next, the software of the microcomputer adopted in the present invention will be outlined.

First, the load increasing process will be described with reference to FIG.

i) Input of Tension Management Information The management method includes P-δ management or μ management, but in this embodiment, P-δ management will be described.

First, input the control limit line. The outline of this limit line will be described with reference to FIG. 4. In FIG. 4, G ₁ and G ₂ are control limit lines. P ₁ is the retaining point load.

The value of the tension management limit is determined for each group that constitutes a plurality of tension members. The tension control limit value of the first group to get nervous is calculated by theoretical calculation considering the experience value, but for the second and subsequent groups, the standard deviation may be calculated from the previous tension result to determine the new tension management limit value. Many. If the task of determining the new tension management limit value is done by hand calculation, it will take time, and it will not be possible to proceed to the next tension task. In the present invention, the operation is automatically performed by the microcomputer, so that it can be done in a short time.

ii) Introduction of tension (detection of prestressed amount and elongation) The measuring device 7 measures the values of the pressure transducer 9 and the displacement gauge 11 and transmits them to the personal computer 1.

iii) CRT screen display or XYRec launch display The control limit lines G ₁ and G ₂ are displayed in advance on the control graph screen.

The load (P) and elongation (δ) are plotted for each increase in tension (usually an increase in a certain unit tension).

Next, after removing the initial slip amount from the transmitted data, the origin of the measured load and elongation is corrected by the method of least squares, and the P-δ curve (see FIG. 4) is displayed on the management graph. .

iv) Load increase command If the measured value is within the control value on the control graph screen,
Issue a load increase command.

If the control value is exceeded, increase the load while displaying a warning.

The judgment as to whether or not the control value is exceeded may be made with only one plot, or may be made with reference to the preceding and following plots.

v) More than or equal to a predetermined load When the predetermined load is reached, the control value is compared again, and if it is within the control value (a lock-off command is issued), fixing is completed and the process is completed.
If it exceeds the control value, an error is displayed, an emergency stop is performed, the load at that time is held (without issuing a lock-off command), and the next manual command is waited for.

vi) Data storage The tension management graph should be recorded on a floppy disk and saved.
This data can be output even after tension work.

vii) Work completion With the above software, the tension work to reach the specified load is completed. In addition to the above software, an emergency interrupt function during automatic computer control, a refill function during repeated tension,
You may add a function to output data for updating control limits, a function to create and output tension control charts, an automatic measurement during manual tension, display of measured values, comparison display with control values, recording of measured values, etc. .

Next, details of the load increasing process from about 10% before the restraint point load to the restraint point load will be described with reference to FIGS. 5 and 6.

FIG. 5 is a graph showing the relationship between the oil discharge time and the tension load in the present invention, and FIG. 6 is a view showing a detailed program (subroutine) of “work end” shown in FIG.

In the present invention, as shown in FIG. 5, a method in which the relationship between the oil discharge time and the tension load is approximately proportional until approximately 10% before the stopping point load is adopted. about
When it exceeds 10%, the straight line becomes a gentle curve, that is, it takes time to reach a predetermined tension load.

The curve shown in FIG. 5 corresponds to the relief valve operating characteristic of the present invention, and the part of the curve up to a predetermined tension load is the guideline in the present invention.

In FIG. 5, the curves A and B show the operating characteristics of the relief valve, but the characteristics in the portion exceeding the predetermined tension load can be set arbitrarily between the curves A and B. For example, a relatively rough setting such as a pressure of a predetermined retaining point load of +0 to +30 kg / cm ² does not affect the load control.

The program shown in FIG. 6 will be outlined. When the load is increased to reach the holding point load, the hydraulic valve (solenoid valve) is closed to stop the load increase. After stopping for 2 seconds, measure the load.

Next, determine how many times the load drop has been checked,
If the load is less than 3 times, then it is judged whether the load has dropped by 10 kg / cm ² or more, and if not, the fixing operation is started.

Note that the present invention is implemented by a computer as a measure against load drop. In FIG. 5, X indicates a state in which there is a load drop until a predetermined tension load is reached, and the computer automatically manages the load drop.

On the other hand, in the conventional manual tension, the load drop measures as shown in FIG. 8 are taken.

The cause of the load drop is that the tension load is slowly transmitted to the fixed end due to the viscous resistance between the PC steel material and the sheath,
It is considered to be based on the phenomenon peculiar to unbonded steel that the load at the tension end drops after a certain period of time.

If there is this load drop, additional introduction is required. In the past, as shown in Fig. 8, the relief valve was set in advance to a load higher than the retaining point load, and several times while watching the oil pressure meter. The hydraulic valve is opened and closed by hand so that it will be over-tensioned and fall within a predetermined stopping point load. However, according to this method, it is necessary to make a professional judgment as to how much higher the relief valve should be set than the retaining point load, and the method of approaching the prescribed retaining point load must be done with excessive tension. There is a risk of inducing plasticization of PC steel.

It should be noted that the relief valve generally has a property that its set position changes to a low load when the oil temperature passing therethrough rises. In this case, this setpoint will no longer be the correct guideline for computer control, and the computer will instruct the hydraulic pump to increase hydraulic pressure indefinitely. In the present invention, when there is no increase in the hydraulic pressure within a certain period of time, that is, when the set value of the relief valve decreases, a warning message is displayed on the display device to prompt the operator to readjust the relief valve, and this is dealt with. ing.

Although one embodiment of the present invention has been described above, the present invention is not limited to this, and may have the following modes.

That is, as shown in FIG. 7, a microcomputer device may be installed in the oil supply / discharge pipes 2, 3.

In the figure, 13 is a microcomputer device for an automatic tension / automatic management system, and the device 13 includes a board computer (with a numeric keypad), a small display device,
A small printer device, a small floppy disk device (or a small magnetic tape device, etc.), a solenoid valve drive device, and a measuring instrument are built in, and a pressure converter 9 and a solenoid valve 10 are also included.

14 is hydraulic pump unit circuit board, 15 is 200V power supply, 16 is
It is a 100V power supply. Note that, in the same figure, the portions having the same reference numerals as those shown in FIG.

The board computer used in this embodiment has a function as a terminal of a host computer. For this reason, the host computer can control a plurality of board computers (at the same time), which is effective when simultaneous tension such as pulling tension is required.

That is, when interlocking tension is performed by pulling tension, the timing can be automatically adjusted by the host computer that centrally manages each microcomputer, so that it is easy to introduce a certain tension force.

The control method of the present invention can be preferably applied to the “reinforcement method for slabs around columns and openings around a prestressed flat plate structure” proposed by the present applicant (Japanese Patent Application No. 61-117526).

[Effects of the Invention] According to the present invention, there are the following effects.

(1) Since it is possible to bring in a microcomputer to the site and fully automate everything from the introduction of tension to its management, it is low cost, does not require a professional engineer, and saves labor costs.
The tension work time is shortened and you can work safely.

(2) In addition, a certain tension can be introduced to ensure quality.

(3) Conventionally, tension control charts and control tables have to be submitted to the manager without delay, but it is possible that they will be submitted after all tension work is completed due to manual work. For this reason, it may be late even if an inappropriate tension is found at that time. On the other hand, in the present invention, the above-mentioned problem can be solved because the microcomputer automatically performs the above.

(4) According to the present invention, the pressure increase gradually decreases from 5 to 30%, preferably about 10%, of the retaining point load.
The open / close control of the solenoid valve (with a slow reaction speed) by the computer can be performed reliably with no time difference, and it can be controlled with an accuracy of the stopping point load of ± 5 kg / cm ² .

(5) Since tension work is performed using the operating characteristics of the relief valve as a guideline, even if a computer or the like malfunctions, excessive tension will not be introduced into PC steel.

(6) Since the final load control is performed by the computer and the relief valve is used to suppress the load rising speed near the final load, the relief valve setting accuracy is not so required. There is no complexity in.

(7) As for the relief valve against the load drop due to viscous resistance, the relief valve has the characteristic of supplying the hydraulic pressure at a slow speed by mechanically gradually increasing the pressure from the vicinity where the load drop easily occurs. It is possible to transmit the tension from the tensioned end to the fixed end, and the work of additional tension due to viscous resistance, which is conventionally performed, is unnecessary.

The apparatus of the present invention can be applied to various industrial hydraulic equipment that requires load control.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an apparatus for carrying out the control method of the present invention, FIG. 2 is a front view showing a case in which the same apparatus is unitized, and FIG. 3 is software used in the present invention. FIG. 4 is a P-δ diagram for tension management adopted in the present invention, FIG. 5 is a graph showing the relationship between the oil discharge time and the tension load in the present invention, and FIG. It is a figure showing the detailed program (subroutine) of the "work end" shown in the figure. FIG. 7 is a schematic explanatory view showing another example of the present invention, FIG. 8 is a graph showing the relationship between the oil discharge time and the tension load in the conventional example, and FIG. 9 is a graph showing the operating characteristics of the conventional relief valve. Is. 1: Hydraulic jack 2: Oil supply pipe 3: Oil discharge pipe 4: Hydraulic pump unit 5: PC 6: Control system 7: Measuring instrument 8: Data insertion part 9: Pressure converter 10: Solenoid valve 10A: Relief valve 11: Displacement meter 12: Control cable 13: Automatic tension / automatic management system equipment group 14: Hydraulic pump unit circuit board 15: 200V power supply 16: 100V power supply 41: Oil tank 42: Hydraulic hose connector 43: Caster 60: Control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Zenzo Asahi 47-3 Mita, Atsugi City, Kanagawa Prefecture Central Technology Research Institute, Sato Industrial Co., Ltd. (72) Inventor Kazuyoshi Kodama 7-2, Doi-cho, Amagasaki City, Hyogo Prefecture Shinko Steel Wire Industry Co., Ltd. (72) Inventor Kenichi Kato 3-14-3 Daisawa, Setagaya-ku, Tokyo JS Co., Ltd. (56) Reference JP-A-58-78712 (JP, A) JP-A-57-43067 (JP, A)

Claims (1)

[Claims] 1. When a hydraulic jack is set on a PC steel material arranged at a predetermined position and a hydraulic pressure is supplied from a hydraulic pump unit with a relief valve to the hydraulic jack to give a predetermined tension force to the PC steel material, A microcomputer device is installed at a tension site, tension management information including at least a control limit value is input to the microcomputer device, and then automatically measured tension force data and measurement data of stroke movement amount of the hydraulic jack, etc. In the automatic control method of introducing and controlling the tension force by transmitting the tension force control signal to the hydraulic pump unit after the microcomputer device compares and judges with the control limit value, the operating characteristic of the relief valve is predetermined. 5 of tension load
An automatic tension jack for prestressed construction characterized by gradually increasing the pressure from a low load of 30% before, and by controlling and controlling the operating characteristic up to a predetermined tension load with the microcomputer as a guideline. Control method.