On-line weight per meter negative difference device

The diameter of rebar has never been measured accurately. At this stage, the negative rate of rebar can only be controlled by manual experience, calipers, and weighing, which cannot maximize the negative rate.

Real-time, online detection provides a digital basis for negative differences. In the past, it could only rely on the experience of steel rolling workers.

DBM actively develops the "Smart Eyes" online differential system to measure the cross-sectional area and precise running length of rebar online in real time, convert it into meter weight, and provide real-time differential rate and changing trends.

Create profits for steel mills: Provide a trend of diameter increase to maximize the negative difference; eliminate out-of-tolerance; a small innovation in the direction of intelligence, providing a basis for direct delivery of hot billets.

Requirements for post-break elongation and weight negative deviation of coiled steel bars and straight steel bars after straightening

Steel bar grade

Elongation after break

Weight negative deviation (%)





















rebar unit weight, rebar weight per meter, rebar production

The rebar online meter weight difference equipment is a new complete set of equipment that integrates optical, mechanical, electrical, visual and computer communication to intelligently monitor the negative deviation of rebar. It is highly advanced, accurate and reliable.


  This equipment monitors the data of base circle, rib, speed, and length of rebar running at high speed, and calculates the negative deviation of the material, thereby providing real-time data reference for the on-site production process.

Customer benefits

For a bar factory with a capacity of 1 million tons, the negative balance increased by 0.2%, and the income increased by 2,000 tons x 3,500 yuan/ton = 7 million!

National standard

Maximum value


Minimum value


Allowable deviation %





Allowable diameter mm





Yield ratio %





Meter weight g





A steel plant has a negative balance of %





Allowable diameter mm





Meter weight g





HiSec Negative difference %





Allowable diameter mm





Meter weight g








Lose weight g


Rebar mm



Weight reduction ratio


Total output tons/year



Total weight loss tons


Steel price yuan/ton





Provides an increasing trend in diameter to maximize the negative difference

Negative difference calculation principle

online cross-sectional size detection

high-precision speed and length measurement

big data

The system uses online cross-sectional size detection + high-precision speed and length measurement + big data to monitor the meter weight of the bar online. Through data cleaning, temperature compensation, sample database and big data analysis, the theoretical comprehensive negative deviation of the rebar can be detected online. To maximize the negative tolerance rate, if successful, the reduction can be adjusted in time to control the negative tolerance of the product, improve the product yield, and improve the negative tolerance stability rate.

Principle of cross-section size detection system

rebar unit weight detector

The online cross-sectional size inspection equipment uses the CCD camera imaging method for measurement. The CCD imaging method refers to a method in which the object to be measured is placed in the object-space telecentric optical path system for imaging, and the CCD chip at the imaging position is used to receive the imaging information for size measurement. There are two main advantages of this measurement method: first, the imaging boundary is clear, the photoelectric signal can be accurate to 1 pixel on the CCD chip, and the measurement accuracy is high; second, the measured object is in the telecentric optical path of the object (i.e. parallel light When moving along the axial or radial direction of the probe in the field of view, the size of the image remains unchanged, which is conducive to high-precision measurement.

Principle of ultra-high frequency and high-precision speed and length measurement

  speed and length measurement

    The speed measurement of the ultra-high frequency and high-precision speed and length measurement system uses the differential Doppler principle. The speed meter adopts spatial filtering technology and uses LED (light-emitting diode) light sources and CCD chips to achieve linear velocity measurement of space luminous particles.

Speed and length measurement

System Features

rebar weight per m
  • Report the trend of roll gap increase, predict deviations and alarm in time
  • High measurement accuracy, strong anti-interference ability, good stability and not easily affected;
  • High stability, strong radiation resistance and high measurement accuracy;
  • Compact design, sturdy equipment, easy to install;     
  • High strength and strong penetrating power, the measurement is not affected by light pollution on the lens surface;
  • Improved a series of problems caused by poor quality of on-site compressed air and purified water;
  • Ultra-high frequency measurement, jitter error elimination technology, high measurement accuracy;
  • It has extremely high spatial resolution, large measurement range, and good velocity and direction sensitivity;
  • Non-contact measurement, fast dynamic response, no wearing parts;
  • This equipment uses the gap between the rolling wire guide grooves for measurement (20mm), and there is no auxiliary device in the center of the equipment;
  • Low operating costs, no wearing parts, no over-steel pipes, and no wear on rolled materials;
  • Simple connection to automation systems via standard networks.

Scope of application

Variety: Threaded bars, threaded high wire, round steel

Specifications: 5mm – 80mm. Covers 12-40 threaded rods

Rolling speed: maximum 120m/s

Equipment accuracy

Object diameter(mm):φ12~φ40

Allowable deviation(mm) 

Measuring rebar ≤± 0.06

(Rebar base circle, longitudinal rib, transverse rib)


Minimum measuring speed(m/min): 0

Maximum measurement speed(m/min): 20000

unit of measurement:m/s,m/min,ft/s

Accuracy: Better than 0.05%

Multiple cutting accuracy: ≤100mm

Comparison with similar products

Capacitive induction rebar wire diameter online monitoring system

Working principle: When the rolling stock passes through the magnetic field generated by the alternating current, eddy currents are generated on the surface of the steel piece. The detection equipment converts it into an electrical signal. By analyzing the changes in the electrical signal, the cross section of the rolling stock is obtained, and then the negative error rate and its change are obtained. trend.

Equipment accuracy: ±0.5% of cross-sectional diameter, or ±1% of meter weight

Installation requirements


AC 220±15% ,50Hz AC 380±15% ,50Hz

Environment humidity (%rh) ≤ 80(non-condensing water)

There should be no dust, water mist, vibration (vibration of the shears, if the vibration is too large, it may need to be added (guides, pinch rollers)

Ambient temperature(℃)

Main equipment: -40~50 Terminal industrial computer: 0~35

Environmental requirements

Precision photoelectric equipment, water and water mist are strictly prohibited; Waterproof sealing measures should be taken near the equipment

Installation location: the equipment is installed after the high bar reducer, and before double-length shearing, a high-speed photoelectric camera measurement system with eight sets of fixed measuring heads is used to measure the outer contour size and length of the passed rolled material in real time online.

Dust removal purge gas: comes with fan and filter

Rebar purge gas: pressure 0.4~0.5MPa; flow rate 3m3/min

Environmental requirements: water and water mist are strictly prohibited for precision photoelectric equipment.

Installation method: hoisting.

Fan installation: Keep away from environments with concentrated dust and high temperatures. The connection of the fan coil should be smooth and bending is strictly prohibited.

Equipment installation site
Equipment Installation Site

Equipment debugging

Online meter weight and size detection system

Confirm that the measuring vehicle is online and the high-pressure blower is turned on. Click the "Start Measurement" button to measure the system. The display screen can be switched during measurement status

Ultra-high frequency and high-precision speed and length measurement system

Confirm that the circuit of the measuring equipment is in normal use, the mirror is 1000mm away from the middle of the bar surface, and the middle position of the bar is irradiated vertically

Measurement deviation check

When replacing rolling stock with different diameters or equipment maintenance,Regularly or irregularly. During the production process, when rolling bars of different specifications, it is recommended to use standard bars in the corresponding specification range for calibration.

Measurement deviation check

When changing specifications, it is necessary to ensure that the length of the bar measured by the equipment is basically consistent with the actual length of the bar, and that the bar does not jump significantly in the roller table.

Equipment maintenance

Dimensional measuring equipment lens maintenance

The maintenance interval for window lenses is approximately 20 days. During maintenance, remove the sealing ring on the online size inspection equipment, wipe the window lens clean with a lens wiper, and then reinstall the sealing ring.

Speed and length measurement equipment maintenance

Make sure the water-cooling and air-cooling equipment are working properly, and confirm that the circuits are normal.

Fan maintenance

Fan filter element maintenance intervals are 3 to 4 weeks (depending on site conditions). During maintenance, take the filter element out of the filter housing and gently drop it on the ground or use a compressed air duct to clean the dust on the filter element.

Water cooler maintenance

The maintenance cycle is about 20 days. Disassemble the water cooler casing and use an air gun to clean the air conditioning filter element and remove the dust.

Dust cleaning

Determined by on-site environmental factors, dust on the equipment should be cleaned regularly.

Industrial computer maintenance

The industrial computer placed in the main control room must be turned on, the program is running, and the communication is normal during use.

Control cabinet

 The control cabinet placed in the power distribution room must be in running state at all times and the relevant parameters must be normal.

Data debugging industrial control

The industrial control is placed in the power distribution room to ensure that it is in running status at all times and the monitoring program runs normally.

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