CN104819233B - A kind of two-freedom eddy current tuned passive damping device - Google Patents

Abstract

A two-degree-of-freedom electric eddy current tuned passive damper, including a mass block, a support frame, a cylindrical rod, a stiffness adjustment nut, a permanent magnet, and a support plate; the cylindrical rod passes through the mass block and is connected to the mass block through threads; The clearance fit of the frame is tightened and positioned by the stiffness adjustment nuts on both sides of the support frame; the bottom of the four support frames is on the same plane; the permanent magnet is fixed on the support plate, and the support plate is pasted on the workpiece. Adjust the position of the support plate to make the two sets of permanent The magnet is located directly below the threaded through hole of the mass block; the invention can effectively reduce the vibration during cutting and realize high-efficiency and high-quality machining of the workpiece; it has better vibration suppression effect, and has fewer parts, simple manufacture, and can be more accurately Adjustable damping, wide range of applications, and good practicability.

Description

A two-degree-of-freedom eddy current tuned passive damper

technical field

The invention provides a two-degree-of-freedom electric eddy current tuned passive damper, which relates to a workpiece structure and a workpiece vibration reduction device in the process of metal cutting, specifically, a two-degree-of-freedom whose stiffness and damping can be adjusted separately An eddy current tuned passive damper can effectively achieve a vibration reduction effect to ensure efficient and high-quality processing of metal parts, and belongs to the field of mechanical processing.

Background technique

The most common problem in metal cutting is the cutting chatter between the tool and the workpiece. Cutting chatter is an extremely harmful phenomenon that destroys the normal cutting process and is the primary factor affecting the surface quality and machining accuracy of the workpiece. At the same time, the machine tool and the tool service life is also affected. The noise generated by flutter during processing will also cause certain damage to the operator's body, and this phenomenon needs to be improved. The present invention is based on this purpose. This patent improves the dynamic characteristics of the machine tool by adjusting the damper parameters. By compensating the weak rigid mode, the damage caused by cutting chatter can be fundamentally avoided.

Dampers fall into two categories: active and passive. The active form of damper has a great effect in theory, but because of its complex hardware and software system and high cost, it is hindered from being applied in actual processing. The passive form damper is widely used because of its simplicity of structure, flexibility of form and easy adjustment of operation. The passive form damper achieves the purpose of suppressing flutter by adjusting its stiffness and damping parameters. At the same time, the damper has two degrees of freedom, and the damper with a single degree of freedom has a more obvious suppression and reduction effect. Traditional passive dampers have the following problems: most of the dampers are contact type, and the vibration energy is absorbed and then dissipated. At the same time, the friction consumption of the contact type damper will lead to damage and failure of the eddy current damper; the suppression frequency band is relatively narrow, It is only effective when the eddy current damper frequency is tuned to the structure controlled frequency and the external excitation covers this frequency content.

Contents of the invention

In view of the above problems, the present invention proposes a two-degree-of-freedom electric eddy current tuned passive damper, which suppresses the chatter problem that occurs during cutting. The inhibitory effect makes it widely used in the field of cutting processing.

The invention provides a two-degree-of-freedom electric eddy current tuned passive damper, which is characterized in that it includes a mass block, a support frame, a cylindrical rod, a stiffness adjustment nut, a permanent magnet and a support plate. The relationship between them is: the cylindrical rod passes through the mass block, and is connected with the mass block through threads; the cylindrical rod and the support frame are in clearance fit, and are tightened and positioned by the stiffness adjustment nuts on both sides of the support frame; the bottom of the four support frames are located on the same Plane; the permanent magnet is fixed on the support plate, and the support plate is pasted on the workpiece, and the position of the support plate is adjusted so that the two sets of permanent magnets are located directly below the threaded through hole of the mass block.

The mass block is a cuboid block made of copper with good electrical conductivity and high density; there is a threaded through hole on the left and right sides of the mass block, the threaded through hole is symmetrical about the geometric center line of the mass block, and the middle part of the threaded through hole is There is an internal thread, which is connected with the external thread in the middle of the cylindrical rod through the internal thread.

There are four sets of support frames, and the structures of the four sets of support frames are exactly the same. There is a through hole on the upper part of the support frame to support two cylindrical rods matched with the mass block, and the through holes are in clearance fit with the cylindrical rods. The bottom plane of the support frame is relatively large, which is convenient for fitting with the workpiece.

There are two sets of cylindrical rods, and the two sets of cylindrical rods are exactly the same. The support frame and the cylindrical rod are fixed by eight identical stiffness adjustment nuts. Each support frame has a stiffness adjustment nut on the inside and outside. The distance between the support frame and the mass block can be changed by the position of the stiffness adjustment nut on the cylindrical rod , thereby changing the stiffness of the damper.

There are eight sets of the stiffness adjusting nuts, all of which are the same. The stiffness adjustment nut changes the damper stiffness by changing the relative position of the support frame and the mass block.

There are two sets of permanent magnets with the same structure, which are respectively located directly below the two through holes of the mass block. The damping ratio of the damper can be adjusted by adjusting the distance between the permanent magnet and the mass block.

The support plate is a cuboid thin plate made of thin aluminum plate, the permanent magnet is fixed on the support plate with special glue, and the support plate is pasted on the workpiece, which saves the trouble of fixing the permanent magnet on the damper.

The above-mentioned two-degree-of-freedom eddy current tuned passive damper has obvious two-order mode characteristics, and can suppress the first-order and second-order modes of the machine tool structure or workpiece. In the cutting vibration, in the first-order mode, the two cylindrical rods provide the mass block with upward vibration synchronously, causing the mass block to vibrate vertically upward; in the second-order mode, the two cylindrical rods provide the mass block with upward vibration asynchronously, The mass rotates around one of the cylindrical rods. A two-degree-of-freedom electric eddy current tuned passive damper of the present invention has the advantages of:

1. The two-degree-of-freedom eddy current tuned passive damper of the present invention is used as a vibration reduction device in the field of mechanical processing, which can weaken the first-order and second-order modes of the workpiece, effectively reduce the vibration during cutting, and realize efficient and high-quality processing of the workpiece;

2. The two-degree-of-freedom eddy-current tuned passive damper of the present invention has a translational degree of freedom and a rotational degree of freedom through the different motion conditions of the two cylindrical rods passing through the through hole of the mass block, and can suppress the first-order Or two-order vibration mode, under the same mass, it has better vibration suppression effect compared with single-degree-of-freedom damper, and has fewer parts, simple manufacturing, parameter adjustment is more convenient than contact passive damper, and can be more accurately Adjust damping.

3. The two-degree-of-freedom eddy-current tuned passive damper of the present invention adopts four support frames, has the characteristics of separable tuning of parameters, and wide frequency band of vibration suppression. When the dynamic characteristics of the workpiece in cutting process change, the stiffness of the damper and the damping ratio Have a certain adjustable interval requirements;

4. The two-degree-of-freedom eddy current tuned passive damper of the present invention can adjust the damper stiffness by adjusting the relative position of the support frame and the mass block, and can adjust the damping ratio of the damper by adjusting the distance between the eddy current damper and the mass block. It can realize complete separation and has good practicability;

5. The two-degree-of-freedom eddy current tuning passive damper of the present invention makes the position of each part relatively fixed through screw connection, and the mass block is made of copper material, which has high density, good thermal conductivity, convenient installation and wide application range;

6. The two-degree-of-freedom eddy-current tuned passive damper of the present invention has simple structure, convenient implementation, low cost, no pollution to the environment, and applies non-contact vibration reduction technology. The eddy current formed by electromagnetic induction can generate a secondary magnetic field and then generate electricity after being absorbed. Form renewable clean energy.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of a two-degree-of-freedom eddy current tuned passive damper of the present invention;

Fig. 2 is a schematic side view of the overall structure of the two-degree-of-freedom eddy current tuned passive damper of the present invention;

Fig. 3 is a schematic top view of the overall structure of the two-degree-of-freedom eddy current tuned passive damper of the present invention;

Fig. 4 is a schematic front view of the overall structure of the two-degree-of-freedom eddy current tuned passive damper of the present invention;

Fig. 5 is a side sectional view of the overall structure of the two-degree-of-freedom eddy-current tuned passive damper of the present invention;

Fig. 6 is a front cross-sectional view of the overall structure of the two-degree-of-freedom eddy current tuned passive damper of the present invention;

Fig. 7 is a flowchart of a method for optimizing parameters of a two-degree-of-freedom eddy current tuned passive damper according to the present invention.

In the picture:

1-mass block 2-support frame 3-cylindrical rod

4-stiffness adjustment nut 5-permanent magnet 6-support plate

101-Threaded through hole 201-Through hole

specific implementation plan

The present invention will be further described in detail below in conjunction with the accompanying drawings.

A two-degree-of-freedom electric eddy current tuning passive damper of the present invention, as shown in Figure 1, Figure 2, Figure 3, and Figure 4, it includes a mass block 1, a support frame 2, a cylindrical rod 3, a stiffness adjustment nut 4, and a permanent magnet 5. Support plate 6.

The relationship between them is: the cylindrical rod passes through the mass block, and is connected with the mass block through threads; the cylindrical rod and the support frame are in clearance fit, and are tightened and positioned by the stiffness adjustment nuts on both sides of the support frame; the bottom of the four support frames are located on the same Plane; the permanent magnet is fixed on the support plate, and the support plate is pasted on the workpiece, and the position of the support plate is adjusted so that the two sets of permanent magnets are located directly below the threaded through hole of the mass block.

As shown in Figures 5 and 6, the mass block 1 is a cuboid block made of copper. There are two threaded through holes 101 on both sides of the mass block 1 , the two threaded through holes 101 have the same structure, are symmetrical about the geometric center line of the side, and have the same distance from the upper bottom surface and the lower bottom surface. There is a section of internal thread in the middle of the threaded through hole 101, which is positioned by connecting the internal thread with the external thread in the middle of the cylindrical rod 3, and the mass block can rotate around the cylindrical rod.

The support frame 2 has four sets, and the structure of the four sets of support frames is the same. There is a through hole 201 at the upper end of the support frame 2. A stiffness adjustment nut 4, two stiffness adjustment nuts 4 are rotated opposite to the support frame 2 to locate the positional relationship between the support frame 2 and the cylindrical rod 3, after the external stiffness adjustment nut 4 of the support frame 2 is unscrewed out of the cylindrical rod 3, the cylindrical rod 3 Take it out from the support frame 2. There are eight sets of rigidity adjustment nuts 4, and eight sets of structures are the same.

The cylindrical rod 3 is an aluminum rod with a section of external thread tapped in the middle. The outer diameter of the outer thread at the middle part is slightly larger than the diameter of the rest of the cylindrical rod 3, and it is convenient and quick to pass through the threaded through hole 101 of the mass block. Both ends of the cylindrical rod 3 are provided with external threads, and four pairs of stiffness adjustment nuts 4 are used to position the cylindrical rod 3 and the support frame 2 to make the damper rigidity adjustment flexible and fast.

There are two sets of permanent magnets 5, and the two sets of permanent magnets have the same structure and are cylindrical. The permanent magnet 5 is installed directly below the two threaded through holes 101 of the mass block 1 to ensure the best cutting effect in cutting vibration reduction. The lower end of the permanent magnet 5 is fixed on the surface of the support plate 6 by a special adhesive, and the permanent magnet 5 can be removed after gently tapping with a hammer. The distance between the permanent magnet 5 and the mass block 1 can be adjusted by increasing or decreasing the quantity of the permanent magnet 5, increasing the quantity of the permanent magnet 5 will increase the damping ratio of the damper, on the contrary, reducing the quantity of the permanent magnet 5 will reduce the damper The damping ratio realizes the quantitative adjustment of the damping ratio of the damper.

The above support frame 2 is located on both sides of the mass block 1. After the damper is installed, the support frame 2 is parallel to the mass block 1. By adjusting the relative position of the cylindrical rod 3 and the mass block 1, and adjusting the relative position between the cylindrical rod 3 and the support frame 2 The position can change the relative position of the support frame 2 and the mass block 1, so that the stiffness of the damper can be continuously adjusted. When the distance between the adjusting support frame 2 and the mass block 1 is longer, the stiffness of the damper is weak, otherwise the stiffness of the damper is stronger. The adjustment of the damper stiffness and the adjustment of the damping ratio are separated, which provides convenience for better finding the dynamic characteristic parameters for suppressing cutting vibration.

In the above-mentioned two-degree-of-freedom electric eddy current tuned passive damper, during cutting vibration, when the two cylindrical rods 3 move up and down at the same time, the vibration direction of the mass block 1 is vertically upward, which is the first-order mode; when the two cylindrical rods 3 move in opposite directions Or when the movement is not synchronous, the mass block 1 does a simple vertical up and down movement, and at the same time rotates around one of the cylindrical rods 3, which is a second-order mode. Therefore, the present invention has two-order mode characteristics, and can weaken the first-order and second-order modes of the workpiece.

In the damper of the present invention, the stiffness of the damper is adjusted by adjusting the distance between the mass block 1 and the support frame 2 through the stiffness adjustment nut 4, and the damping ratio is adjusted by adjusting the distance between the permanent magnet 5 and the mass block 1, so the present invention is a two-degree-of-freedom eddy current Tuning the passive damper, when suppressing the cutting vibration, the mass block 1 vibrates under the action of the cylindrical rod 3, which can suppress the vibration of the workpiece. By adjusting the distance between the support frame 2 and the mass block 1, the stiffness of the damper can be changed. Changing the damping ratio of the damper by changing the distance between the permanent magnet 5 and the mass block 1 can make the damping effect of the damper reach an optimal state, and it is more convenient to adjust than the contact passive damper with the same volume, and the damping effect is better.

In the damper of the present invention, during the actual cutting process, two sets of permanent magnets 5 are fixed on the structure of the workpiece to be suppressed with special glue; in order to allow the eddy current damping to exert the best effect, both sets of permanent magnets 5 must be placed on the mass block 1 Right below the threaded through hole 101, the damper has the best damping effect at this time. In order to optimally suppress the vibration of the workpiece, it is first necessary to identify the dynamic parameters of the workpiece and test the dynamic characteristics of the main structure of the workpiece to obtain the natural frequency, damping ratio, mode shape, and modal quality of the workpiece; then through finite element simulation or The numerical method obtains the optimal damping and damping ratio when the damper is adjusted to the optimal parameters. During formal cutting, the natural frequency of the damper is identified and the dynamic characteristics are tested, and the damping ratio and stiffness of the damper are adjusted to achieve the best suppression effect, as shown in Figure 7.

Claims (3)

1. A two-degree-of-freedom electric eddy current tuned passive damper is characterized in that: it comprises a mass block, a support frame, a cylindrical rod, a stiffness adjustment nut, a permanent magnet and a support plate; their mutual relationship is: the cylindrical rod wears pass through the mass block, and connect with the mass block through threads; the cylindrical rod and the support frame are in clearance fit, and are tightened and positioned by the stiffness adjustment nuts on both sides of the support frame; the bottoms of the four support frames are on the same plane; the permanent magnets are fixed on the support plate, The plate is pasted on the workpiece, and the position of the support plate is adjusted so that the two sets of permanent magnets are located directly below the threaded through holes of the mass block; The mass block is a cuboid block with good electrical conductivity and high density; there is a threaded through hole on the left and right sides of the mass block, the threaded through hole is symmetrical about the geometric center line of the mass block, and there is an internal thread in the middle of the threaded through hole. The internal thread is connected with the external thread in the middle of the cylindrical rod; There are four sets of support frames, and the four sets of support frames have the same structure. There is a through hole in the upper part of the support frame, which supports two cylindrical rods matched with the mass block. , to facilitate the lamination with the workpiece; There are two sets of cylindrical rods, and the two sets of cylindrical rods are exactly the same; the support frame and the cylindrical rods are fixed by eight identical rigidity adjustment nuts, and each support frame has a rigidity adjustment nut on the inside and outside, through which the stiffness adjustment nuts The position on the cylindrical rod can change the distance between the support frame and the mass block, thereby changing the stiffness of the damper; There are eight sets of stiffness adjusting nuts, all of which are the same; the stiffness adjusting nuts change the stiffness of the damper by changing the relative position between the support frame and the mass block; There are two sets of permanent magnets with the same structure, which are respectively located directly below the two through holes of the mass block, and the damping ratio of the damper can be adjusted by adjusting the distance between the permanent magnet and the mass block; The support plate is a cuboid thin plate, the permanent magnet is fixed on the support plate with special glue, and the support plate is pasted on the workpiece, which saves the trouble of fixing the permanent magnet on the damper. 2. A two-degree-of-freedom electric eddy current tuned passive damper according to claim 1, characterized in that: the cuboid block mass is made of copper. 3. A two-degree-of-freedom eddy current tuned passive damper according to claim 1, characterized in that: the support plate is made of thin aluminum plate.