JPS61207764A - Variable speed mixer for fresh concrete - 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]

[Field of Industrial Application] The present invention uses an electric motor as the drive source in a variable speed mixer, and adjusts the rotational speed of the electric motor to the optimum rotational speed corresponding to the load at the time of load and the best stirring blade circumferential speed. This article relates to a variable speed mixer for ready-mixed concrete.

[Conventional technology]

Conventional ready-mixed concrete mixers of this type include a mixer that can change the rotation speed in two stages (Japanese Patent Publication No. 59-9854), a mixer that can change the rotation speed with a pole change motor (Japanese Patent Application Laid-open No. 163614-1987), A mixer using a hydraulic motor (Special Publication No. 57-43405). A mixer (Utility Model Application Publication No. 59-9808) whose rotational speed can be adjusted according to the load is known. However, in any of the mixers, it is not possible to select the rotation speed of the electric motor by increasing or decreasing the frequency of the frequency converter as in the present invention using a rotation speed selection means, and furthermore, it is not possible to select the rotation speed of the electric motor by increasing or decreasing the frequency of the frequency converter as in the present invention, and furthermore, it is not possible to select the rotation speed of the electric motor by increasing or decreasing the frequency of the frequency converter as in the present invention. There is no technical idea to adjust the motor rotation speed to the optimum speed.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a mixer for ready-mixed concrete, which is characterized in that the rotational speed of the electric motor of the drive source is controlled and adjusted to be most convenient for mixing ready-mixed concrete. To explain this in more detail, the relationship between power consumption and motor rotation speed is as follows: H = TXN/974 [H: electric power (kW), T: ) - Luk (kg-m)
, N: number of rotations (R, P, M)). Assume now that the electric power when the load torque is TI is Hl, and the rotational speed is N1. On the other hand, if the load torque increases to T2 and the rotational speed is constant as N1=N2, the electric power H2 will increase more than the electric power H1, but the rotational speed N2 will be reduced to N2.
By decelerating to lXTl/T2, H2 can be kept constant at 81. Applying this, for example, in order to adjust the motor rotation speed to the optimum speed corresponding to the load and the best circumferential speed of the stirring blade in each of the high speed rotation range, medium speed rotation range, and low speed rotation range, it is necessary to Taking the high speed rotation range as an example, this means reducing the motor rotation speed N so that the electric power H does not exceed a certain value in response to the temporarily large torque T that occurs immediately after gravel is added, and crosstalk progresses. The rotational speed N is gradually increased in accordance with the load torque, which gradually decreases over time. and,
The rotation speed N of the electric motor is increased until it reaches the peripheral speed of the stirring blade that is most convenient for mixing of fresh concrete, and mixing of the fresh concrete is continued in the desired rotation speed range.

[Means to solve the problem]

The present invention has been made for the purpose of producing excellent ready-mixed concrete that cannot be obtained with conventional variable speed mixers for ready-mixed concrete, and uses an electric motor as a driving source. The apparatus is equipped with a rotation speed selection means that can increase or decrease the circumferential speed of stirring blades for kneading aggregate by changing the frequency and adjust the motor rotation speed to an optimum motor speed. Generally, when mixing fresh concrete using a batcher plant, the rotational speed of a mixer is usually 10 to 20 R, P, M using a tilting mixer with a rotating container. A forced mixing mixer in which the stirring shaft rotates with a fixed container is usually 20 to 35 R, P, M, and when trying to mix mortar with one mixer, the rotation speed is usually the same as that at the time of concrete mixing. A rotation speed of about 1.3 to 2.5 times the rotation speed is required. By configuring the present invention as in the first embodiment,
This has successfully solved many problems in ideally producing the best ready-mixed concrete using a single mixer.

【Example】

The variable speed mixer of the present invention will be explained based on the drawings. Figure 1 shows the load torque, power and rotation speed when fresh concrete is mixed with the variable speed mixer of the invention, Figure 2 shows the automatic control circuit for controlling the rotation speed of the variable speed mixer, and Figure 3 shows the automatic control circuit for controlling the rotation speed of the variable speed mixer. , a tilting type variable speed mixer with a rotating container, and FIG. 4 shows a two-shaft forced kneading variable speed mixer with a non-rotating container. In the figure, the drive source of the variable speed mixer is assumed to be electric motor 1,
A speed reducer 3 is connected to the electric motor 1 either directly or via a belt 2, and a rotating tool having stirring blades 4 is connected to the speed reducer 3 for rotation. The procedure for using the mixer is to first put sand, water, cement, and sand, water, admixture, cement, and gravel into a container 10 and mix them with mortar. In this first step, the inverter 6 supplies high-frequency power to the electric motor 1 according to a command signal from the speed setting device 5, and as the electric motor 1 rotates, the stirring blade 4 rotates at a high speed (peripheral speed) suitable for mortar crosstalk. doing. Next, gravel and an admixture are put into the same container IO to mix the fresh concrete. In this second step, the stirring blade 4 is turned on in response to a command from the speed setting device 5 that receives a signal to start adding gravel. Reduces speed to medium speed suitable for concrete cross-tracking,
Mix the concrete. The signal to the speed setting device 5 for decelerating to medium speed rotation is as follows:
A signal from a timer with a set time may be used, and the timing may be adjusted to the start of gravel feeding. In addition, the admixture can be mixed into water in advance, and the first
It may be added during the process. When the fresh concrete is mixed, the electric motor 1 is further decelerated by the same control operation as described above, the stirring blades 4 are rotated at a low speed, and the concrete is discharged without separation. In this third step, if it is desired to retain the mixed concrete in the container 10, low speed rotation is continued to maintain the quality of the fresh concrete. On the other hand, if an overload occurs in each process, the overcurrent detector 7 detects the current of the motor 1. Input to the calculator 8. The arithmetic unit 8 is connected to this overcurrent detector 7.
The overcurrent input data from the speed setting device 5 and the setting value from the speed setting device 5 are calculated, and a command is issued to the inverter 6. Inverter 6
reduces the power frequency by a value corresponding to the overcurrent and supplies it to the motor 1. As the electric motor 1 rotates, the stirring blade 4 decelerates. The overcurrent detector 8 may be a torque detector that dynamically detects rotational torque generated at any position from the electric motor 1 to the stirring blade 4, in addition to being electrically operated. According to experiments, in the second step, medium speed rotation of 30 to 35R, P, and H was performed for 20 to 35 seconds for 15 seconds with a nominal capacity of 1.0 mm.
10 to 20 R, P, M was suitable for 25 seconds and in the third step of discharging or retaining the mixed concrete. There are various embodiments of ready-mixed concrete depending on differences in strength, slump, maximum coarse aggregate diameter, etc., and the order and amount of input. They are also different. Therefore, if the speed setting device 5 is connected with the combination storage device 9 and the optimum rotation speed according to the combination can be selected and set within each rotation range, more optimal crosstalk can be achieved for each embodiment. Better quality fresh concrete can be obtained.

【Effect of the invention】

The variable speed mixer of the present invention is constructed as described above, and has the following significant effects. (1) Mortar is mixed at a high speed rotation suitable for mixing mortar, and fresh concrete is mixed at a medium speed rotation suitable for mixing fresh concrete. can be discharged and retained while retaining the (2) The electric motor drive, which is equipped with a frequency converter and speed selection means, is efficient and can quickly change gears in response to the maximum torque that occurs immediately after gravel is added, or sudden overloads. Since the rotational speed of the electric motor is selected in accordance with the load in each rotational range and the best circumferential speed of the stirring blade, the electric motor can be downsized and power consumption can be saved. (3) By simply attaching a part of the device of the present invention to the existing constant rotation type fresh concrete mixer mounted on a batcher plant, the mixer can achieve the same performance as the variable speed mixer of the present invention, and can be made using an electric motor. There is no need to replace the mixer or modify the existing mixer. (4) In the first step, water, sand, and cement are stirred at a high speed suitable for mixing mortar, so the process of dispersing cement and wetting the surface of cement particles with water can be performed well and in a short time. Therefore, when adding an admixture later for the purpose of improving water reduction properties, it is possible to add the admixture earlier than with conventional fixed rotation mixers, and because it is well dispersed in the cementola, the reduction property is further reduced. improves.

[Brief explanation of drawings]

Figure 1 shows the load torque and rotational speed when fresh concrete is mixed using the variable speed mixer of the invention. Figure 2 shows an automatic control circuit for controlling the rotation speed of a variable speed mixer, Figure 3 shows a tilting type variable speed mixer with a rotating container, and Figure 4 shows a two-axis forced kneading system with a rotating container. A variable speed mixer is shown. l ・・・・・・・・・・Electric motor 3・・・・・・・・Reducer 6 ・・・・・・・・・・Inverter 8・・・・・・・・・・Computer Patent applicant: Kitagawa Iron Works Co., Ltd. Fue 1 Button 11 → 8H Omachi Secret Procedures Amendment (voluntary) June 9, 1985 1, Indication of the case 1985 Patent Application No. 047087 2, Name of the invention Variable speed mixer for concrete 3, relationship with the case of the person making the amendment Applicant address: 15-77 Motomachi, Fuchu City, Hiroshima Prefecture, subject of amendment Description and drawings 6, contents of amendment (1) Page 9, line 16 Add the following sentence between line 17. The relationship between load torque, power, and rotation speed in the above cross-talk process will be explained using Figure 1, taking the medium-speed rotation range as an example. , the rotational speed of the electric motor l when adjusted so that the electric power is always a constant value H1 is shown by the two-dot chain line a.For the constant rotational speed Nl, which is the best stirring blade circumferential speed for concrete crosstalk, the electric power is constant. If the value H1 or less, concrete is continued to be mixed at this rotation speed N1, but the temporary large torque T generated immediately after gravel is added
2, if the number of revolutions of the electric motor 1 is maintained constant at N1, the electric power increases from a constant value H1 as shown by the two-dot chain line N2. However, N
Slow down to 2. Similarly, as the crosstalk progresses, the rotational speed gradually increases as the load torque gradually decreases. Then, the rotation speed of the electric motor is increased until it reaches the circumferential speed of the stirring blade that is best for the most freshly mixed concrete, and when the rotation speed Nl, which is the best circumferential speed of the stirring blade, is reached, the electric power is Rotational speed a that gives a constant value H1
Instead of increasing along the line, even if the power becomes less than H1, the mixing of fresh concrete continues at the desired rotation speed N1. The upper limit value H1 of the electric power is determined in consideration of the characteristics of the electric motor, such as the temperature rise of the coil and the life of the bearing, so as to maximize the ability of the electric motor with respect to the load on the stirring blade. (2) Symbols a, N1, N2, Hl, N in the diagram of Figure 1.
2 and T2 are added in Figure 1 of the attached sheet. Claims (1) The electric motor used as the drive source for the circumferential speed of the stirring blade is a frequency converter (equipped with a frequency converter for increasing or decreasing the frequency of the frequency converter in stages). The variable speed for fresh concrete is equipped with a rotation speed selection means to adjust the motor rotation speed to the best stirring blade circumferential speed in the JdL range for one basket straight plate. Mixer.

Claims (1)

[Claims] (1) The driving source of the stirring blades for kneading the aggregate is an electric motor, and the electric motor is equipped with a frequency converter, and the frequency of the frequency converter is increased or decreased in stages to adjust the rotation speed of the electric motor. In addition to being able to select from three speed ranges: high speed range, medium speed range, and low speed range, the rotation speed can be adjusted to the optimum motor rotation speed that corresponds to the load and the best stirring blade circumferential speed in each of the above ranges. Variable speed mixer for ready-mixed concrete equipped with means.