A double-frequency motor-driven roller mill

Abstract

A roller mill driven by a dual variable frequency motor comprises a three-phase AC power supply, a fast roller variable frequency drive mechanism, a slow roller variable frequency drive mechanism, a first fast grinding roller, a first slow grinding roller, a second fast grinding roller and a second slow grinding roller, wherein the first fast grinding roller, the first slow grinding roller, the second fast grinding roller and the second slow grinding roller are arranged in parallel, the first fast grinding roller and the first slow grinding roller form a first pair of rollers that cooperate with each other, the second fast grinding roller and the second slow grinding roller form a second pair of rollers that cooperate with each other, the three-phase AC power supply supplies power to the fast roller variable frequency drive mechanism and the slow roller variable frequency drive mechanism respectively, the power output end of the fast roller variable frequency drive mechanism is respectively connected to the first fast grinding roller and the second fast grinding roller, and the power output end of the slow roller variable frequency drive mechanism is respectively connected to the first slow grinding roller and the second slow and fast grinding roller. The present invention has the following technical effects: 1) simple structure; 2) adjustable output; 3) adjustable speed ratio of fast and slow grinding rollers; 4) energy saving.

Description

Technical Field

[0001] The present invention belongs to the technical field of grain processing machinery, and particularly relates to a roller mill driven by a double-frequency motor. Background Art

[0002] In a complete set of wheat flour milling equipment, the roller mill is the most important main equipment. Its process performance is crucial for the subsequent flour milling effect, and the energy consumption of the roller mill accounts for a large proportion. In the flour milling process, multiple skin mills, multiple core mills, and multiple slag mills in the grinding and crushing process all use roller mills. Therefore, improving the technology of the roller mill is extremely important for improving the overall process level and efficiency of the flour mill.

[0003] The existing roller mill mainly consists of grinding rolls, a feeding mechanism, a feeding device, a clutch rolling and rolling gap adjusting mechanism, a transmission and a frame, etc. Its working principle is as follows: A pair of cylindrical grinding rolls with the same diameter rotate in opposite directions at different speeds. There is a certain gap between the surfaces of the two rolls, and this gap forms a crushing area along the entire length of the grinding roll. When the material passes through the crushing area, it is crushed by the extrusion, shearing, and grinding actions of the two grinding rolls.

[0004] Currently, the transmission part of the traditional roller mills widely used at home and abroad includes two parts: power input and transmission between the fast and slow grinding rolls. 1. Power input: Usually, each pair of grinding rolls is independently driven by a motor. The motor directly drives the fast roll through a V-belt for primary reduction. 2. Transmission between the fast and slow grinding rolls: This transmission is also called constant-speed transmission, and its function is to ensure an accurate transmission ratio between the fast and slow grinding rolls. According to process and structural requirements, the constant-speed transmission of the roller mill usually adopts two methods: gear transmission or synchronous toothed belt transmission. 1) Gear transmission mainly uses standard gears or non-standard long-tooth gears. Since the latter compensates for the deficiency of non-continuous transmission when using standard gears, the vibration and noise are significantly improved compared with the former, and only two pairs of matching numbers with the same transmission ratio are required. Therefore, it relatively becomes an ideal choice for the constant-speed transmission of the roller mill. 2) Synchronous toothed belt constant-speed transmission. Currently, the roller mill generally uses a double-sided toothed wedge belt (or double-sided toothed belt) as the transmission method. To meet the transmission requirements and adapt to the change of the center distance during automatic clutch rolling and rolling gap adjustment, the structure is complex. The energy transmission routes of the roller mill using this type of transmission method under no-load and load conditions are respectively as Figure 1 and Figure 2 shown; Figure 1 and Figure 2 The reference numerals in are: 1 - motor, 2 - transmission belt, 3 - fast grinding roll, 4 - fast roll constant-speed gear (pulley), 5 - slow roll constant-speed gear (pulley), 6 - slow grinding roll, 30 - grain. The energy transfer under no-load is as shown by the straight arrow in Figure 1 , 1→2→3→4→5→6; the energy transfer under load is as shown in Figure 1As shown by the straight arrows in the figure, 1→2→3→6→5→4.

[0005] Traditional roller mills are low-cost and easy to adjust, but their structure is complex and has the following disadvantages: 1) Gear fixed-speed transmission produces noise and vibration, requires oil lubrication, and is prone to leaking pollutants. 2) Synchronous toothed belt fixed-speed transmission has belt tearing, deviation, and uneven belt wear, and the belt life is short. 3) High mechanical manufacturing precision is required. 4) The only adjustable process parameter is the rolling gap. 5) The roller speed and the ratio of fast and slow roller speeds cannot be adjusted during operation. 6) The output cannot be adjusted. 7) It is difficult to ensure that the motor always runs in the optimal efficiency range. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides a roller mill driven by a dual-frequency motor. On the basis of the traditional roller mill, the present invention replaces the original two ordinary asynchronous motors with two frequency-converted motors, eliminates the complex structure of the fixed-speed transmission mechanism (fixed-speed gear or pulley transmission), realizes a new energy transmission mode, and completely solves all the above-mentioned shortcomings of the traditional roller mill. The present invention has the advantages of simple structure, low noise, small vibration, low energy consumption, high output, etc.

[0007] To solve the above technical problems, the present invention adopts the following technical scheme: a dual-frequency motor driven roller mill, comprising a three-phase AC power supply, a fast roller frequency conversion drive mechanism, a slow roller frequency conversion drive mechanism, a first fast grinding roller, a first slow grinding roller, a second fast grinding roller and a second slow grinding roller, the first fast grinding roller, the first slow grinding roller, the second fast grinding roller and the second slow grinding roller are all arranged in parallel, the first fast grinding roller and the first slow grinding roller form a group of first pairs of rollers that cooperate with each other, the second fast grinding roller and the second slow grinding roller form a group of second pairs of rollers that cooperate with each other, the three-phase AC power supply supplies power to the fast roller frequency conversion drive mechanism and the slow roller frequency conversion drive mechanism respectively, the power output end of the fast roller frequency conversion drive mechanism is respectively connected to the first fast grinding roller and the second fast grinding roller, and the power output end of the slow roller frequency conversion drive mechanism is respectively connected to the first slow grinding roller and the second slow and fast grinding roller.

[0008] The fast roller frequency conversion drive mechanism includes a first frequency converter, a first frequency conversion motor, a first double-groove pulley, a first fast roller pulley and a second fast roller pulley; the three-phase AC power supply is connected to the first frequency conversion motor through the first frequency converter, the first double-groove pulley is installed on the main shaft of the first frequency conversion motor, the first fast roller pulley is installed at one end of the central axis of the first fast grinding roller, the second fast roller pulley is installed at one end of the central axis of the second fast grinding roller, and the first fast roller pulley and the second fast roller pulley are respectively connected to the first double-groove pulley through a first transmission belt.

[0009] The slow roller variable-frequency drive mechanism includes a second frequency converter, a second variable-frequency motor, a second double-groove pulley, a first slow-roller pulley, and a second slow-roller pulley; a three-phase AC power supply is connected to the second variable-frequency motor through the second frequency converter. The second double-groove pulley is installed on the main shaft of the second variable-frequency motor. The first slow-roller pulley is installed at one end of the central shaft of the first slow grinding roller, and the second slow-roller pulley is installed at one end of the central shaft of the second slow grinding roller. The first slow-roller pulley and the second slow-roller pulley are respectively driven and connected to the second double-groove pulley through a second transmission belt.

[0010] Adopting the above technical solution, the working principle and process of the present invention are as follows:

[0011] The first variable-frequency motor drives the first fast grinding roller and the second fast grinding roller to rotate in the same direction through two first transmission belts respectively; the second variable-frequency motor drives the first slow grinding roller and the second slow grinding roller to rotate in the same direction through two second transmission belts respectively; the first fast grinding roller and the first slow grinding roller form a first pair of rollers, and the first fast grinding roller and the first slow grinding roller rotate towards each other. The absolute value of the linear velocity of the outer circumferential surface of the first fast grinding roller is greater than the absolute value of the linear velocity of the outer circumferential surface of the first slow grinding roller;

[0012] The second fast grinding roller and the second slow grinding roller form a second pair of rollers, and the second fast grinding roller and the second slow grinding roller rotate towards each other. The absolute value of the linear velocity of the outer circumferential surface of the second fast grinding roller is greater than the absolute value of the linear velocity of the outer circumferential surface of the second slow grinding roller; the two first transmission belts are arranged on the same side of the axial direction of the two pairs of rollers; the two second transmission belts are arranged on the other side of the axial direction of the two pairs of rollers. The first variable-frequency motor drives the first fast grinding roller, the second fast grinding roller or more fast grinding rollers simultaneously through multiple groups of first transmission belts, and the second variable-frequency motor drives the first slow grinding roller, the second slow grinding roller or more slow grinding rollers simultaneously through multiple groups of second transmission belts.

[0013] The three-phase AC power supply is respectively connected to the power inputs of the first frequency converter and the second frequency converter through wires; the power outputs of the first frequency converter and the second frequency converter are respectively connected to the first variable-frequency motor and the second variable-frequency motor through wires; the first variable-frequency motor is connected to the first fast grinding roller and the second fast grinding roller through a first double-groove pulley and two first transmission belts; the second variable-frequency motor is connected to the first slow grinding roller and the second slow grinding roller through a second double-groove pulley and two second transmission belts; the first fast grinding roller and the first slow grinding roller are separated and not in contact when the flour mill is unloaded, and interact with each other through the material contact when loaded; the second fast grinding roller and the second slow grinding roller are not in contact when the flour mill is unloaded, and interact with each other through the material contact when loaded; the DC buses of the first frequency converter and the second frequency converter are connected in parallel; according to the above principle, the first frequency converter is connected to the first variable-frequency motor to drive the first fast grinding roller, the second fast grinding roller or more fast grinding rollers simultaneously through multiple groups of first transmission belts, the second frequency converter is connected to the second variable-frequency motor to drive the first slow grinding roller, the second slow grinding roller or more slow grinding rollers simultaneously through multiple groups of second transmission belts, or the first frequency converter is connected to the first variable-frequency motor or multiple first variable-frequency motors to independently drive the first fast grinding roller, the second fast grinding roller or more fast grinding rollers, and the second frequency converter is connected to the second variable-frequency motor or multiple second variable-frequency motors to independently drive the first slow grinding roller, the second slow grinding roller or more slow grinding rollers. The linkage relationship is also within the technical scope involved in the present invention.

[0014] In summary, the present invention has the following technical effects:

[0015] 1) Simple structure. Each pair of rollers of the traditional roller flour mill is driven by the same motor. To achieve the opposite rotation of the fast grinding roller and the slow grinding roller at a fixed speed ratio, an additional constant-speed mechanism is required. This constant-speed mechanism not only has a complex mechanical structure but also requires high installation and manufacturing precision. In the present invention, each pair of rollers is driven by two variable-frequency motors that can be independently adjusted in speed. The speeds of the fast grinding roller and the slow grinding roller can be adjusted separately, so no constant-speed mechanism is needed.

[0016] 2) Adjustable output. Each pair of rollers of the traditional roller flour mill is driven by one motor. Since the motor speed is not adjustable, to change the output, especially to increase the output, only longer grinding rollers can be used, but replacing different lengths of grinding rollers can only be achieved by replacing the entire flour mill. In the present invention, the output can be increased or decreased by adjusting the speeds of the first variable-frequency motor and the second variable-frequency motor respectively, without replacing the flour mill.

[0017] 3) Adjustable speed ratio of the fast and slow grinding rollers. The speed ratio of the fast grinding roller and the slow grinding roller of the traditional roller flour mill (i.e., the ratio of the linear speed of the surface of the fast grinding roller to the linear speed of the surface of the slow grinding roller) is determined by the deceleration of the transmission gears or transmission belts and is a fixed value that cannot be adjusted during operation. In the present invention, the speed ratio of the fast and slow grinding rollers can be adjusted by changing the parameters of the frequency converter.

[0018] 4) Energy saving. The driving motor of the traditional roller mill cannot guarantee high operating efficiency when the process parameters change. High efficiency can only be guaranteed by optimizing the mechanical structure, fixing the process parameters and fixing the output, but this is difficult to guarantee in the actual production process. Since the present invention adopts a variable frequency motor, the frequency converter can ensure that the variable frequency motor guarantees high operating efficiency within a larger speed regulation range through variable frequency speed regulation, thereby achieving energy saving effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the energy transmission of the conventional roller mill gear constant speed drive when unloaded;

[0020] Figure 2 It is a schematic diagram of the energy transfer of the conventional roller mill gear constant speed drive under load;

[0021] Figure 3 It is a schematic diagram of the structure of the present invention;

[0022] Figure 4 It is a schematic diagram of the linkage relationship between the variable frequency motor, the fast grinding roller and the slow grinding roller;

[0023] Figure 5 It is a schematic diagram of the control principle of the present invention;

[0024] Figure 6 It is a schematic diagram of the energy transmission of the novel transmission of the present invention when no-load;

[0025] Figure 7 It is a schematic diagram of the new transmission energy transfer of the present invention under load. DETAILED DESCRIPTION

[0026] Figures 3 - 7 As shown, a dual-frequency motor driven roller mill of the present invention comprises a three-phase AC power supply 7, a fast roller frequency conversion drive mechanism, a slow roller frequency conversion drive mechanism, a first fast grinding roller 8, a first slow grinding roller 9, a second fast grinding roller 10 and a second slow grinding roller 11, the first fast grinding roller 8, the first slow grinding roller 9, the second fast grinding roller 10 and the second slow grinding roller 11 are arranged in parallel, the first fast grinding roller 8 and the first slow grinding roller 9 form a group of first pairs of rollers that cooperate with each other, the second fast grinding roller 10 and the second slow grinding roller 11 form a group of second pairs of rollers that cooperate with each other, the three-phase AC power supply 7 supplies power to the fast roller frequency conversion drive mechanism and the slow roller frequency conversion drive mechanism respectively, the power output end of the fast roller frequency conversion drive mechanism is respectively connected to the first fast grinding roller 8 and the second fast grinding roller 10, and the power output end of the slow roller frequency conversion drive mechanism is respectively connected to the first slow grinding roller 9 and the second slow and fast grinding roller 11.

[0027] The high-speed roller variable-frequency drive mechanism includes a first frequency converter 12, a first variable-frequency motor 13, a first double-groove pulley 14, a first high-speed roller pulley 15, and a second high-speed roller pulley 16; a three-phase AC power supply 7 is connected to the first variable-frequency motor 13 through the first frequency converter 12. The first double-groove pulley 14 is installed on the main shaft of the first variable-frequency motor 13. The first high-speed roller pulley 15 is installed at one end of the central shaft of the first high-speed grinding roller 8, and the second high-speed roller pulley 16 is installed at one end of the central shaft of the second high-speed grinding roller 10. The first high-speed roller pulley 15 and the second high-speed roller pulley 16 are respectively connected to the first double-groove pulley 14 through a first transmission belt 22 for transmission connection.

[0028] The low-speed roller variable-frequency drive mechanism includes a second frequency converter 17, a second variable-frequency motor 18, a second double-groove pulley 19, a first low-speed roller pulley 20, and a second low-speed roller pulley 21; a three-phase AC power supply 7 is connected to the second variable-frequency motor 18 through the second frequency converter 17. The second double-groove pulley 19 is installed on the main shaft of the second variable-frequency motor 18. The first low-speed roller pulley 20 is installed at one end of the central shaft of the first low-speed grinding roller 9, and the second low-speed roller pulley 21 is installed at one end of the central shaft of the second low-speed grinding roller 11. The first low-speed roller pulley 20 and the second low-speed roller pulley 21 are respectively connected to the second double-groove pulley 19 through a second transmission belt 23 for transmission connection.

[0029] The working principle and process of the present invention are as follows:

[0030] The first variable-frequency motor 13 drives the first high-speed grinding roller 8 and the second high-speed grinding roller 10 to rotate in the same direction through two first transmission belts 22 respectively; the second variable-frequency motor 18 drives the first low-speed grinding roller 9 and the second low-speed grinding roller 11 to rotate in the same direction through two second transmission belts 23 respectively; the first high-speed grinding roller 8 and the first low-speed grinding roller 9 are the first pair of rollers, and the first high-speed grinding roller 8 and the first low-speed grinding roller 9 rotate towards each other. The absolute value of the linear velocity of the outer circumferential surface of the first high-speed grinding roller 8 is greater than the absolute value of the linear velocity of the outer circumferential surface of the first low-speed grinding roller 9;

[0031] The second high-speed grinding roller 10 and the second low-speed grinding roller 11 are the second pair of rollers, and the second high-speed grinding roller 10 and the second low-speed grinding roller 11 rotate towards each other. The absolute value of the linear velocity of the outer circumferential surface of the second high-speed grinding roller 10 is greater than the absolute value of the linear velocity of the outer circumferential surface of the second low-speed grinding roller 11; the two first transmission belts 22 are arranged on the same side of the axial direction of the two pairs of rollers; the two second transmission belts 23 are arranged on the other side of the axial direction of the two pairs of rollers. The first variable-frequency motor 13 drives the first high-speed grinding roller 8, the second high-speed grinding roller 10 or more high-speed grinding rollers through multiple groups of first transmission belts 22 at the same time, and the second variable-frequency motor 18 drives the first low-speed grinding roller 9, the second low-speed grinding roller 11 or more low-speed grinding rollers through multiple groups of second transmission belts 23 at the same time.

[0032] The three-phase AC power supply 7 is respectively connected to the power inputs of the first frequency converter 12 and the second frequency converter 17 through wires; the power outputs of the first frequency converter 12 and the second frequency converter 17 are respectively connected to the first variable-frequency motor 13 and the second variable-frequency motor 18 through wires; the first variable-frequency motor 13 is connected to the first fast grinding roller 8 and the second fast grinding roller 10 through the first double-groove pulley 14 and two first transmission belts 22; the second variable-frequency motor 18 is connected to the first slow grinding roller 9 and the second slow grinding roller 11 through the second double-groove pulley 19 and two second transmission belts 23; the first fast grinding roller 8 and the first slow grinding roller 9 are separated and do not contact when the flour mill is unloaded, and interact through the contact of materials when loaded; the second fast grinding roller 10 and the second slow grinding roller 11 do not contact when the flour mill is unloaded, and interact through the contact of materials when loaded; the DC buses of the first frequency converter 12 and the second frequency converter 17 are connected in parallel; according to the above principle, the first frequency converter 12 is connected to the first variable-frequency motor 13 to drive the first fast grinding roller 8, the second fast grinding roller 10 or more fast grinding rollers simultaneously through multiple groups of first transmission belts 22, and the second frequency converter 17 is connected to the second variable-frequency motor 18 to drive the first slow grinding roller 9, the second slow grinding roller 11 or more slow grinding rollers simultaneously through multiple groups of second transmission belts 23. Or the first frequency converter 12 is connected to the first variable-frequency motor 13 or multiple first variable-frequency motors 13 to independently drive the first fast grinding roller 8, the second fast grinding roller 10 or more fast grinding rollers, and the second frequency converter 17 is connected to the second variable-frequency motor 18 or multiple second variable-frequency motors 18 to independently drive the first slow grinding roller 9, the second slow grinding roller 11 or more slow grinding rollers. The linkage relationship is also within the technical scope involved in the present invention.

[0033] Figure 6 The energy transfer during no-load is as shown by the straight arrows in Figure 6 : 13 → 22 → 8; 18 → 23 → 9; Figure 7 The energy transfer during load is as shown by the straight arrows in Figure 7 : 13 → 22 → 8 → 9 → 23 → 18. Comparing Figure 1 、 Figure 6 , and Figure 2 、 Figure 7 it can be seen that the energy cycle and enclosure of the traditional roller flour mill are realized through the mechanical structure, while the energy cycle and enclosure of the roller flour mill involved in the present invention are realized through the electrical system, which not only simplifies the mechanical structure but also enriches the process parameters, laying a foundation for improving the process effect and the system automation level.

[0034] This embodiment does not impose any formal restrictions on the shape, material, structure, etc. of the present invention. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention all belong to the protection scope of the technical solution of the present invention.

Claims

1. A roller mill driven by a dual frequency conversion motor, Features: It includes a three-phase AC power supply, a fast roller frequency conversion drive mechanism, a slow roller frequency conversion drive mechanism, a first fast grinding roller, a first slow grinding roller, a second fast grinding roller and a second slow grinding roller, the first fast grinding roller, the first slow grinding roller, the second fast grinding roller and the second slow grinding roller are all arranged in parallel, the first fast grinding roller and the first slow grinding roller form a group of first rollers that cooperate with each other, the second fast grinding roller and the second slow grinding roller form a group of second rollers that cooperate with each other, the three-phase AC power supply is respectively supplied to the fast roller frequency conversion drive mechanism and the slow roller frequency conversion drive mechanism, the power output end of the fast roller frequency conversion drive mechanism is respectively connected to the first fast grinding roller and the second fast grinding roller, and the power output end of the slow roller frequency conversion drive mechanism is respectively connected to the first slow grinding roller and the second slow and fast grinding roller; The fast roller frequency conversion drive mechanism includes a first frequency converter, a first frequency conversion motor, a first double-groove pulley, a first fast roller pulley and a second fast roller pulley; The three-phase AC power supply is connected to the first variable frequency motor through the first frequency converter, the first double-groove pulley is installed on the main shaft of the first variable frequency motor, the first fast roller pulley is installed at one end of the central axis of the first fast grinding roller, the second fast roller pulley is installed at one end of the central axis of the second fast grinding roller, and the first fast roller pulley and the second fast roller pulley are respectively connected to the first double-groove pulley through a first transmission belt; The slow roller frequency conversion drive mechanism includes a second frequency converter, a second frequency conversion motor, a second double-groove pulley, a first slow roller pulley and a second slow roller pulley; The three-phase AC power supply is connected to the second variable frequency motor through the second frequency converter, the second double-groove pulley is installed on the main shaft of the second variable frequency motor, the first slow roller pulley is installed at one end of the central axis of the first slow grinding roller, the second slow roller pulley is installed at one end of the central axis of the second slow grinding roller, and the first slow roller pulley and the second slow roller pulley are respectively connected to the second double-groove pulley through a second transmission belt; The first variable frequency motor drives the first fast grinding roller and the second fast grinding roller to rotate in the same direction respectively through two first transmission belts; the second variable frequency motor drives the first slow grinding roller and the second slow grinding roller to rotate in the same direction respectively through two second transmission belts; the first fast grinding roller and the first slow grinding roller form a first pair of rollers, the first fast grinding roller and the first slow grinding roller rotate in opposite directions, and the absolute value of the linear velocity of the outer cylindrical surface of the first fast grinding roller is greater than the absolute value of the linear velocity of the outer cylindrical surface of the first slow grinding roller; The second fast grinding roller and the second slow grinding roller form a second pair of rollers, the second fast grinding roller and the second slow grinding roller rotate in opposite directions, and the absolute value of the linear velocity of the outer circumference of the second fast grinding roller is greater than the absolute value of the linear velocity of the outer circumference of the second slow grinding roller; the two first transmission belts are arranged on the same side of the axial direction of the two pairs of rollers; the two second transmission belts are arranged on the other side of the axial direction of the two pairs of rollers; The three-phase AC power supply is connected to the power input of the first frequency converter and the second frequency converter respectively through wires; the power output of the first frequency converter and the second frequency converter is connected to the first frequency conversion motor and the second frequency conversion motor respectively through wires; the first frequency conversion motor is connected to the first fast grinding roller and the second fast grinding roller through the first double-groove pulley and two first transmission belts; The second variable-frequency motor is connected to the first slow grinding roller and the second slow grinding roller through a second double-groove pulley and two second transmission belts; the first fast grinding roller and the first slow grinding roller are separated and not in contact when the flour mill is unloaded, and interact with each other through the contact of materials when loaded; the second fast grinding roller and the second slow grinding roller are not in contact when the flour mill is unloaded, and interact with each other through the contact of materials when loaded; the DC buses of the first frequency converter and the second frequency converter are connected in parallel.

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