JPS63207595A - Method of controlling liquid jet cutter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method of controlling a liquid jet cutting device such as a water jet device or an abrasive jet device, and particularly relates to a method for controlling a liquid jet cutting device such as a water jet device or an abrasive jet device. This invention relates to an improved method for cutting well.

[Prior art] Conventional methods for cutting or dismantling reinforced concrete structures include the diamond force cutting method, the play crab method, and the hydraulic jacking method, but these methods have problems such as noise, vibration, and dust. .

By the way, recently, as buildings and facilities have aged, there has been an increase in renovation work such as making buildings more intelligent, and when renovating hospitals, hotels, etc., it is necessary to maintain the functions of these facilities in an operating state. In many cases, renovation work must be carried out. For this reason, it has become difficult to apply the conventional methods mentioned above in this field of construction, and recently water jet,
Alternatively, a cutting method using an abrasive jet is attracting attention.

The abrasive jet method cuts the workpiece by spraying high-pressure jet water mixed with abrasives onto the workpiece.This jet method has the following features: (1) No noise (2) No vibration (3) ) It has the advantage of being able to cut reinforcing bars at the same time.

By the way, in a conventional cutting device using this abrasive jet method, cutting conditions such as jet pressure, nozzle feed rate, abrasive mixture amount, and nozzle diameter are constant during the cutting process. That is, in the conventional Si[, the cutting conditions are set in advance to appropriate values derived empirically depending on the thickness, strength, etc. of the object to be cut.

In the case of reinforced concrete structures, the reinforcing bars are more difficult to cut than the concrete parts, and the thickness of the concrete varies depending on the location. For this reason, if cutting is performed under constant cutting conditions as described above, there will be problems such as uncut portions and decreased work efficiency.

In other words, if the cutting conditions are set to a place where it is easy to cut, such as by increasing the feed rate, uncut material will be left, and if the cutting conditions are set to a place where it is difficult to cut, such as by decreasing the feed rate, energy loss will occur. This causes the inconvenience of lowering work efficiency.

In order to eliminate such inconvenience,
The proposal shown in Publication No. 8574 includes a cutting nozzle that injects an abrasive material using high-pressure jet water, and a detection device that uses a rod-like tentacle to detect uncut portions at a subsequent position in the cutting direction. and a control device that controls the forward and backward movement of the nozzle based on a signal from the detection device, and when an uncut portion is detected by the detection device, the nozzle is moved back once and then moved forward.

However, even in this conventional technique, the above-mentioned cutting conditions are constant during cutting, and therefore, when an attempt is made to reliably eliminate uncut material, there is a problem that the work efficiency is not improved any further.

This invention was made in view of these circumstances, and provides a liquid jet device that optimally controls the jet capacity by appropriately controlling the cutting conditions according to the cutting state of the object to be cut during cutting. It is intended to provide a control method.

[Means and effects for solving the problem] Therefore, in the present invention, the cutting nozzle is moved only in one direction within a predetermined stroke range, and the cutting state of the object to be cut is detected during cutting, and the detection result is When it is determined that the cutting state is not appropriate based on the above, at least one control element among the nozzle feed speed, jet pressure, and amount of abrasive material is variably controlled.

Further, in the second invention, when moving the nozzle from the start point to the end point in a predetermined stroke range, the cutting state of the object to be cut is detected, and if it is determined that there is an uncut portion based on the detection result, the nozzle is moved to the predetermined stroke range. moving the distance in the opposite direction, increasing the jet capacity by varying at least one control element of the nozzle feed rate, jet pressure, and amount of abrasive material, and moving the nozzle in the forward direction again under the changed conditions. That's what I do.

Furthermore, in the third invention, the nozzle reciprocates at high speed in both forward and reverse directions within a predetermined stroke range, and during cutting, detects the cutting state of the object to be cut, and based on the detection result, it is determined that there is uncut material. In this case, the position of the uncut part is calculated, and during subsequent nozzle movement, if the nozzle is at a position corresponding to the uncut part, at least one control element of the nozzle feed speed, jet pressure, and amount of abrasive material is controlled. In addition to increasing the jet performance by varying the amount, the nozzle is moved at high speed when the nozzle is located at a position other than the position corresponding to the uncut area.

[Example] Hereinafter, the present invention will be described in detail according to an example shown in the accompanying drawings.

FIG. 2 shows an example of a system configuration of an abrasive jet device.

In this system, the hydraulic pressure generated in the hydraulic unit 1 is guided to the low pressure chamber 41 of the pressure increaser TFI 3 via the switching valve 2, and drives the piston 5. On the other hand, water is supplied in advance to the ultra-high pressure chamber 6 of the pressure booster 3 from the water supply pump 7, and this water is supplied to the ultra-high pressure chamber 6 in the ratio 'Ap/A of the cross-sectional area A of the low-pressure chamber 4 and the cross-sectional area A of the ultra-high pressure chamber 6. The pressure is increased according to the pressure increase ratio. The piston 5 reciprocates according to the switching operation of the switching valve 2, thereby making it possible to continuously obtain ultra-high pressure water from the ultra-high pressure chambers 6 on both sides. The pressure of this ultra-high pressure water is adjusted by an electromagnetic relief valve 8, and then an accumulator 9 and a filter 0. It is supplied to the nozzle part 12 via the valve 11. In the nozzle part 12, the abrasives supplied from the abrasive tongue 13 are mixed, and an abrasive jet 15 is ejected from the nozzle 14.
5 to cut the reinforced concrete structure 16. The nozzle section 12 is driven to be fed in the cutting direction by a nozzle feeding device 25. This reinforced concrete 16 has reinforcing bars 17
has been established. A nozzle cover 18 is provided on the surface of the cut object 16, and a recovery cover 19 is provided on the back surface of the cut object 16, and these covers 18 and 19 prevent the jet 15 from scattering to the outside. The water and abrasive material used for cutting are collected by a collection device 22 via collection hoses 20 and 21.
．． It will be collected on the 23rd.

When cutting reinforced concrete with this abrasive jet device, as shown in Fig. 3, at the cutting start point After forming the eye hole 24, the nozzle head 12 is moved in the feeding direction to cut the concrete 16. In this cutting process, when the nozzle feed rate is V1 and the jet pressure is P, the jet capacity U has the following relationship.

Jet capacity ■Jet energy density α Nozzle entrance pressure x flow rate / Nozzle feed rate α (Nozzle inlet pressure) / Nozzle feed rate cxP3/2/V In addition to this, jet capacity also changes depending on the mixing amount of abrasive material j do. Therefore, in order to optimally control the jet performance, it is sufficient to adjust the jet pressure P1, the nozzle feed rate v1, and the mixing amount j of the abrasive material.

By the way, during the cutting process, the jet stream takes various paths as shown in FIGS. 3 and 4 depending on the jet capacity U.

The state shown in Fig. 4 (a) is a state in which the jet capacity is excessive, and in this case, it is thought that the feed rate is slow, the jet pressure is too high, or there is too much polishing, resulting in energy loss. big. FIG. 4(b) shows the optimum cutting condition. In FIG. 4(C) or (d), it is thought that the feeding speed is high, the jet pressure is low, or the amount of abrasive is small, and uncut portions 26 are present.

FIG. 5 shows the relationship between jet capacity and cutting depth. Under optimal conditions, the cutting depth is an appropriate amount larger than the concrete thickness d (see FIG. 3).

FIG. 1 shows an example of a configuration for implementing the control method according to the present invention. It is roughly divided into a control section 40 that adjusts jet performance.

The sensor 31 in the detection unit 30 detects the cutting state of the object without contacting the object.
The figure shows an example of such a tree. FIG. 7 is a sectional view taken along line AA' in FIG.

In this configuration, the elastic plate 33 is attached to the fixing ring 3 at the rear side of the tip of the abrasive nozzle 12 with respect to the nozzle feeding direction.
4 and bolts 35, and a strain gauge 36 is attached to the rear surface of this elastic plate 33. The output of the strain gauge 36 is input to a strain meter 37, and the measured value of the strain meter 37 is input to a cutting condition determination section 32 shown in FIG.

According to this configuration, if an uncut portion of the reinforcing bar 17 or the like is left during cutting, the jet water is reflected toward the nozzle side and further backward in the direction of movement, so that the elastic plate 33 is deflected and deformed by this reflected water 38. As a result, an output signal proportional to the amount of deformation can be obtained from the strain gauge 36. When the nozzle is completely cut with no uncut portion, no output signal is obtained from the strain gauge 36 because no reflected water 38 is generated toward the nozzle side.

Therefore, as shown in FIG. 8, if the relationship between the output of the strain gauge 36 and the degree of cutting is determined in advance by experiment, the degree of cutting of the concrete 16 can be determined according to the detected output of the strain gauge 36 during cutting. can do. The relationship shown in FIG. 8 is preset in the cutting degree determining section 32, and the determining section 32 determines the degree of cutting based on the output of the strain meter 37 and the set relationship. The judgment output of the cutting condition judgment section 32 is controlled by the control section 40 tlI! It is input to @41.

In this case, the control unit 40 controls (1) jet pressure P(2
) Nozzle feed rate ■ (3) Abrasive supply amount j is controlled to perform variable control of the jet capacity U.

The motor driver 42 drives a motor (not shown) of the nozzle feeding device 25 (see FIG. 2), and the motor driver 42 adjusts the rotation speed of the motor based on a command signal input from the control device 41. , variably controls the nozzle feed speed V.

The electromagnetic relief valve 8 (see Fig. 2) adjusts the water pressure supplied to the nozzle 12, and adjusts the abrasive jet nozzle inlet pressure by varying its set pressure in accordance with a command signal input from the control device 41. Vary P.

The abrasive indication and adjustment device 43 adjusts the amount of abrasive supplied from the abrasive tank 13 to the nozzle section 12 in accordance with a command signal input from the control device 41. Further, in this case, a nozzle position sensor 44 is provided to sequentially detect the position of the nozzle 12 during cutting, and the sensor 44
is composed of, for example, a potentiometer.

Hereinafter, examples of the operation of such a configuration will be explained using three embodiments.

Embodiment I FIG. 9 is a flowchart showing a first embodiment of the present invention.

In this embodiment, cutting is performed by moving the nozzle only in one direction e from the start position X to the stroke end X as shown in FIG. In this embodiment, nozzle feed speed V and jet pressure P are used as control parameters.

First, the operator inputs appropriate values v1 and Pl, which are determined empirically based on the thickness and strength of the sample, into the control device 41 as initial values regarding the feed rate ■ and the jet pressure P (step 100), and the hydraulic unit 1 Then, the water supply pump 7 is started, and abrasive jet water is injected from the nozzle 14. Then, the operator moves to the starting position
, after the through hole is formed, start moving the nozzle (
Step 110). During cutting, the control device 41 detects the nozzle position based on the output of the position sensor 44, and the nozzle 12 is at the stroke end
If the cutting state has not been reached (step 120), then the cutting state is determined based on the output of the cutting state determining section 32 (
Step 130). If it is determined from this judgment result that there is uncut material or that the degree of cutting is excessive, the control I table device 1 issues a command to the electromagnetic relief valve 8 and the motor driver 42,
Jet pressure P and nozzle feed rate V are changed to appropriate values P2 and v2 (step 140).

That is, in this embodiment, the cutting state is sequentially determined while moving the nozzle forward, and when it is detected that the cutting state has deviated from the optimum state, the nozzle feed speed ■ and the jet pressure P are
to the initial value V1. From P1 to the appropriate value V2. It is set to automatically change to P2. Thereafter, when the control device 41 detects that the nozzle section 12 has reached the set stroke X (step 120), it stops the nozzle movement (step 150) and stops the jet injection (step 160).

Fig. 10 shows how the nozzle feed speed V changes when an uncut portion is detected, and the nozzle feed speed is controlled at a low speed from the initial speed ■1 to speed ■2 at the position where there is an uncut portion. .

This first embodiment has the advantage that the cutting time is short because the nozzle is moved only in one direction and only the cutting conditions are adjusted without stopping the nozzle even when excessive or insufficient cutting is detected. However, the response of the control system requires coordination.

・Embodiment ■ FIG. 11 is a flowchart showing a second embodiment of the present invention.

In this second embodiment, the nozzle is basically fed in only one direction, but if insufficient cutting is detected, the nozzle is moved back a predetermined distance, and the nozzle is restarted after changing the cutting condition. When the nozzle moves forward and excessive cutting is detected, the nozzle is stopped and the cutting conditions are changed.

First, the operator selects the initial cutting condition P1 as in the previous embodiment.
Input V1 (step 200), and then start moving the nozzle (step 210).

During cutting, set stroke end X. If the nozzle has not reached (step 220), then the degree of cutting is sequentially determined based on the determination result of the detection unit 30' (step 230).
). In this determination, if the cutting condition is optimal, the nozzle speed V and jet pressure P are set to initial values 1 and Pl, and cutting is performed (step 240). If it is determined in the above determination that the degree of cutting is not optimal, the control device 41 determines whether the degree of cutting is excessive or insufficient based on the determination result of the detection unit 30 (step 250).

If it is determined that the disconnection state is insufficient, the control device 41
outputs a stop command to the motor driver 42, and the nozzle 12
Immediately stop the position sensor 4 at this time.
Nozzle position X=Xo is confirmed from the output Xo of No. 4 (step 260). Next, the control wJ device @41 gives a retreat command to the motor driver 42 to move the nozzle 12 backward by a predetermined distance ΔX (step 270). After confirming that the nozzle position has retreated to Xo-ΔX based on the output of the position sensor 44 (step 280), the control device 41 stops the nozzle (step 29o). Next, the control device 41
increases the set pressure of the electromagnetic relief valve 8 from the initial pressure P1 to the appropriate pressure P2 (P2 > Pl), reduces the command signal to the motor driver 42, and changes the nozzle feed speed from the initial speed v1 to the appropriate speed V2 (V2 < Vl).
) by increasing the jet capacity U (step 300).

Then, under such conditions (P=P2, V=V2>) the nozzle advances again.The nozzle advances under these conditions until it is determined in step 230 that the cutting condition has become optimal, and the jet JEEP and nozzle speed ■ are set to initial values P1 and V when the cutting condition is optimal.
1 (step 240).

Further, if it is determined in step 250 that the degree of cutting is excessive, the control device 41 controls the nozzle 12
is immediately stopped (step 310), and the set pressure of the electromagnetic relief valve 8 is changed from the initial value P1 to the appropriate value P3.
(P3<Pl), and the motor driver 42
The jet performance U is decreased by increasing the command signal for the nozzle and increasing the nozzle feed speed V to an appropriate speed V3 (v3>Vl) (step 320). Then, the nozzle is restarted to advance under such cutting conditions (P=P3, V=V3). Control under this condition is continued until it is determined in step 230 that the degree of cutting has become optimal, as described above. In this way, when the cutting condition is excessive, the cutting conditions are varied without retracting the nozzle.

The control device 41 then moves the nozzle section 12 to the set stroke
When it is detected that it has reached (step 220),
Stopping the nozzle movement (step 330),
The jet injection is stopped (step 340).

Regarding such control, FIG. 12 shows an example of variable control of the nozzle feed speed. As can be seen from the figure, when insufficient cutting is detected, the nozzle is moved back a predetermined distance △X, and then the low speed control is performed. Nozzle feeding is restarted by till (V2), and if excessive cutting is detected, the nozzle speed is changed to high V without retracting the nozzle.
3 to restart nozzle feeding.

In this second embodiment, the cutting time for stopping and retracting the nozzle is longer than in the first embodiment, but cutting is more reliable and the response speed of the control system is relatively slow. It has the advantage of being okay.

- Example ■ In this third example, the object to be cut is cut by reciprocating the nozzle multiple times at high speed. For this reason, the configuration of the sensor 31 for detecting the cutting state is as shown in FIG. 13, for example.

That is, in this configuration, the elastic plates 3 are provided on both sides of the nozzle part 12.
3 and 33' are provided, and strain gauges 36 and 36' are attached to these elastic plates 33 and 33', respectively. The detection principle is the same as shown in FIG. 6 above.

In this embodiment, the nozzle is reciprocated at high speed within a certain stroke range (x≦X≦×8) as shown in FIG. For this reason, it is not possible to cut the concrete 16 with one feed of the nozzle, and at the beginning of cutting, the concrete 16 is
As shown in a), the surface portion of the concrete has been cut, but the reinforcing bar portion 17 and beyond are not cut. Therefore, in this case, jet water is reflected toward the nozzle at all nozzle positions. Therefore, in this case, the output of the strain gauge sensor 36' can be obtained over the entire range. Figure 14 (
In the state shown in b), the jet water has reached the reinforcing bars 17, and although some of the reinforcing bars 17 have been cut, they have not yet penetrated the concrete 16. In this case as well, the output of the strain gauge sensor 33' can be obtained in all sections as described above.

Fig. 14 (C) shows a state where the cutting has progressed further and the jet water 1 has cut the concrete part, and a part of the reinforcing bar 17 and the concrete behind it remain, but other concrete parts are completely disconnected. In this case, the output of the sensor 36 is zero because reflected water does not occur in the penetrated concrete part, but the output of the sensor 36 is obtained in the uncut part near the reinforcing bars 17 due to the reflected water, so the output of the strain gauge sensor 36 is The position of the uncut portion can be detected.

Experiments have shown that when the nozzle is moved back and forth at high speed in this way, the time required to cut concrete of a certain thickness can be reduced compared to when the nozzle is moved once at low speed. ing.

FIG. 15 is a flowchart showing an example of the operation of the third embodiment, and the overall operation of this embodiment will be explained below with reference to this flowchart.

First, the operator inputs cutting conditions such as nozzle speed V1 and stroke length X as described above (step 400).
), the hydraulic unit 1 and the water supply pump 7 are started, and a water jet mixed with abrasive material is injected from the nozzle 12,
Begin cutting (step 410). Then, the control device 41 drives the nozzle feeding device 25 to move the nozzle at high speed at an initial speed v1 (step 420). control tI
When the I device 41 detects from the detection value of the nozzle position sensor 44 that the nozzle section 12 has reached the stroke end x 8 (step 430), it next determines whether the uncut position can be determined based on the output of the detection section 30. (Step 440). What is the state in which the uncut position can be determined? Sensor 3
6 or 36' is in the state shown in FIG. 14(C).

If the uncut position cannot be determined, the control device 41 outputs a reversal command to the motor driver 42, and causes the nozzle feeding device 25 to move the nozzle portion 12 in the reverse direction at high speed (step 450). Such high-speed reciprocating operation of the nozzle is continued until the determination in step 440 becomes YES.

If it is possible to determine the uncut position in step 440, the control device 41 sends a stop command to the motor driver 42 to stop the nozzle (step 460), and outputs the output from the sensor 36, 36'. The uncut position is calculated based on the following (step 470). And after this calculation, the system 490). During this reverse movement, the control device 41
The current position of the nozzle is sequentially determined based on the output of the position sensor 44 (step 500), and if the determined current position is outside the range of the calculated uncut portion, a high speed command is sent to the motor driver 42, For example, set the nozzle to the initial speed ■1
(step 540), and when the nozzle position determined above is within the range of the uncut portion,
A low speed command is sent to the motor driver 42 to move the nozzle at a low speed V2 that is lower than the initial speed v1 (step 530). The control device 41 moves the nozzle under such control, and when the nozzle reaches the stroke end (step 510), stops the nozzle (step 550), and further stops the ejection of the water jet/abrasive material. Thereafter, the hydraulic unit 1 and the water supply pump 7 are stopped to complete the cutting (step 560).

FIG. 16 shows such speed control. Initially, the nozzle is moved back and forth at a speed v1, and when a portion of the uncut portion remains, the uncut portion is removed by feeding the nozzle once. That's what I do. During the last feeding drive described above, the nozzle is driven at a low speed (■2) at the position where there is an uncut portion, thereby increasing the jet capacity, and at a position where there is no uncut portion, the nozzle is moved at a high speed. Two-stage switching control is performed.

In addition, in this embodiment, at a position where there is no uncut portion, the jetting of the abrasive jet may be stopped and the nozzle may be moved at high speed, and the speed during this high-speed movement may be made higher than the initial speed (1). You can do it like this. Further, in the third embodiment, the uncut portion is removed by one last feeding, but the uncut portion may be removed by two or more feedings.

- Tsuchi - By the way, in the first to third embodiments described above, the jet capacity was adjusted using the nozzle feed rate and the jet pressure as control elements, but it was also possible to add the abrasive mixture amount to the control elements. It may also be possible to control one of these three control elements. That is, in the present invention, the jet capacity is adjusted by controlling at least one of the nozzle feed speed, the jet pressure, and the amount of abrasive material.

[Effects of the Invention] As explained above, according to the present invention, the cutting state of the object to be cut is detected, and if the cutting state is not appropriate, the jet pressure, nozzle feed speed, and abrasive mixture amount are adjusted to adjust the jet performance. Since it is optimally controlled, the workpiece can be automatically cut in a short time without leaving uncut parts or energy loss, and work efficiency can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a control configuration for carrying out the method of the present invention, FIG. 2 is a conceptual diagram showing an example of the overall configuration of an abrasion jet equipment to which this invention is applied, and FIG. 3 is a cutaway diagram. An explanatory diagram explaining the process, etc., Figure 4 is a diagram showing the jet flow in various cutting states, Figure 5 is a graph showing the relationship between jet ability and cutting depth, and Figure 6 is a graph showing the cutting state. 7 is a cross-sectional view taken along line AA' in FIG. 6, FIG. 8 is a graph showing the relationship between the strain gauge output and the degree of cutting in the sensor, and FIG.
FIG. 10 is a flowchart showing the first embodiment of the method of the present invention, FIG. 10 is a graph showing the relationship between nozzle feed speed and nozzle position in the first embodiment, and FIG. 11 is a flow chart of the method of the present invention. Flowchart showing the second embodiment, No. 12
The figure is a graph showing the relationship between nozzle position and nozzle feed speed in the second embodiment, FIG. 13 is a graph showing an example of the sensor configuration used in the third embodiment of the present invention, and FIG. 15 is a flowchart showing the third embodiment of the method of the present invention, and FIG. 16 is a nozzle in the third embodiment. It is a graph showing the relationship between position and nozzle feed speed. DESCRIPTION OF SYMBOLS 1... Hydraulic unit, 2... Switching valve, 3... Pressure booster, 5... Piston, 7... Water supply pump, 8...
Electromagnetic relief valve, 9...Accumulator, 10...
・Filter, 11... Valve, 12... Nozzle part,
13... Abrasive tank, 14... Nozzle, 15...
- Abrasive jet, 16... Reinforced concrete structure, 17... Rebar, 18... Nozzle cover, 19
...Recovery cover, 22゜23...Recovery device, 25.
... Nozzle feeding device, 26 ... Uncut, 30 ... Detection section, 31 ... Sensor, 32 ... Cutting condition judgment section,
33... Elastic plate, 34... Fixing ring, 35...
・Bolt, 36...Strain gauge, 37...Strain meter, 40
...control unit, 41...control device, 42...motor driver, 43...abrasive material adjustment device, 44...nozzle position sensor. ℃ θ 67 boat C/ Figure 6 Not the most number of people 1 Dai Wu Heshu Huichu Figure 7 Figure 8

Claims (3)

[Claims] (1) A liquid jet cutting device that cuts the object by ejecting a water jet or an abrasive jet mixed with an abrasive from a nozzle to the object and moving the nozzle along the object. In the control method, the nozzle during cutting is moved only in one direction within a predetermined stroke range, and the cutting state of the object to be cut is detected during cutting, and if it is determined that the cutting state is not appropriate based on the detection result, 1. A method of controlling a liquid jet cutting device, characterized in that at least one control element among nozzle feed speed, jet pressure, and amount of abrasive material is variably controlled. (2) A liquid jet cutting device that cuts the object by ejecting a water jet or an abrasive jet mixed with an abrasive from a nozzle to the object and moving the nozzle along the object. In the control method, when moving the nozzle from the start point to the end point within a predetermined stroke range, the cutting state of the object to be cut is detected, and if it is determined that there is uncut material left uncut based on the detection result, the nozzle is moved in the opposite direction by a predetermined distance. The jet capacity is increased by varying at least one control element of the nozzle feed rate, the jet pressure, and the amount of abrasive material, and the nozzle is moved in the forward direction again under the changed conditions. A method for controlling a liquid jet cutting device characterized by: (3) A liquid jet cutting device that cuts the object by ejecting a water jet or an abrasive jet mixed with an abrasive from a nozzle to the object and moving the nozzle along the object. In the control method, the nozzle reciprocates at high speed in both forward and reverse directions within a predetermined stroke range, and during cutting, the cutting state of the object to be cut is detected. Based on the detection result, if it is determined that there is uncut material, The position of the uncut part is calculated, and when the nozzle is moved after that, when the nozzle is at a position corresponding to the uncut part, at least one control element of the nozzle feed speed, jet pressure, and amount of abrasive material is varied. A method of controlling a liquid jet cutting device, characterized in that the jet capacity is increased and the nozzle is moved at high speed when the nozzle is located at a position other than the position corresponding to the uncut portion.