RU2568004C2 - Reversive mechanism for rotary-linear conversion - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: reversive mechanism contains the housing with guiding slides, the slide, the parasitic pulleys installed on axes in the housing, two deflecting pulleys installed on axes in the slide, the first and second differential pulleys fixed on the shaft in the housing and linked by mechanical rotation transmission with the reversive drive, the infinite belt, enclosing the parasitic, deflecting and differential pulleys. Besides, in addition on the axes in the housing and in the slide respectively two rejecting pulleys in each are installed, which are enclosed by the belt which forms additional loops with parallel branches.

EFFECT: increase of rigidity of the reversive mechanism.

4 cl, 7 dwg

Description

The present invention relates to mechanical engineering and can be used in drives of reciprocating moving working bodies of various machines, in particular in drives of reciprocating movement of tables of surface grinding machines.

Known reversible table drive mechanism of an electromechanical surface grinding machine, containing a base in the form of a cross table, a movable table installed in the linear guides of the cross table, an electric rotation drive, a mechanical reduction in speed, a gear pulley interacting with a gear belt, the ends of which are rigidly fixed to opposite the edges of the movable table (US 4271637, class. B24B 7/02, 1981, paragraph 3 of the claims).

This reversible mechanism allows you to increase the range of speed control of the longitudinal feed of the table, which makes it possible to expand technological capabilities due to the implementation of various types of grinding processing on one machine, differing in the speed of longitudinal feed: pendulum grinding, mortise depth grinding, grinding in short strokes. The mechanism is widely used in the construction of electromechanical grinding machines.

The disadvantages of this reversing mechanism are the low load capacity and rigidity of the belt drive, since the drive forces are transmitted through one loaded branch of the belt, the need to use an additional reduction gear in the rotation drive, and also a sufficiently high unevenness of the table travel, which reduces the quality of processing.

Also known is a reversible table mechanism of a surface grinding machine, comprising a base, straight guides in which a table is mounted, a toothed belt fixed with ends to brackets rigidly fixed to the table, while the toothed belt covers a pulley system consisting of two pairs of pulleys located on the table bracket , and two pairs of pulleys located on a fixed base, forming on them two large and two small loops located on opposite sides of the housing for fastening the belt, as well as the drive eversivny motor rotary motion, a mechanical speed reduction transmission associated with the pulley, disposed on the fixed base (US 4485594, cl. V24V 49/00, 1984, at pp. 4-7 of the claims).

This mechanism has high rigidity due to the use of four branches of the drive belt for the drive.

Its disadvantages are a low gear ratio, which makes it necessary to use additional reduction gears in the rotation drive and the presence of a large branch of the belt.

Closest to the claimed is a reversing mechanism for converting rotational motion into translational motion, comprising a housing, slider guides, a slider, spurious pulleys mounted on the housing, two deflecting pulleys mounted on the slider, two differential pulleys mounted in the housing and connected by a rotational mechanical transmission with reversible drive, endless belt covering spurious, deflecting and differential pulleys arranged in such a way that the branches of the belt covering deflecting The pulleys mounted on the slider are parallel to each other, with each belt branch interacting with one of the differential pulleys, and the product of the ratio of the diameters of the differential pulleys and the gear ratio of the mechanical transmission of rotation has a value other than 1, and the mechanical transmission of rotation can be performed in in the form of a gear or belt drive, and a belt drive can be made in the form of a gear belt transmission (EP 0161431, cl. F16H 19/06, 1985, paragraphs 1-7 claims, prototype).

Spurious pulleys mounted on the housing serve to increase the angle of coverage of the differential pulleys, their number is determined by the shape of the loops formed by the drive belt, and does not matter. An analysis of the kinematics of the prototype allows us to conclude that the speed of the translational motion of the slider is determined by the difference in peripheral speeds of the differential pulleys

where ω ₁ , ω ₂ are the angular velocities of the first and second differential pulleys; D ₁ , D ₂ - the diameters of the first and second differential pulleys.

Consideration of this expression allows us to conclude that in order to ensure the operability of the mechanism, the condition

The ratio of the peripheral speeds of the differential pulleys is determined by the ratio of their diameters and the gear ratio of the mechanical transmission. This ratio is calculated as the product of the gear ratio of the mechanical transmission of rotation by the ratio of the diameters of the differential pulleys. The difference of this ratio from unity is a condition for ensuring the operability of the mechanism according to paragraphs. 1-4 of the claims of the prototype

where i _1,2 is the gear ratio of the mechanical transmission of rotation connecting the first and second differential pulleys.

This mechanism provides a high gear ratio between the rotation drive and the output link - the slider, which eliminates the need for additional reduction gears of rotation. The speed of the slide is determined by the expression

The disadvantage of this mechanism is the low rigidity due to the use of only two working branches of the drive belt.

The technical task of the invention is to increase the rigidity of the reversing mechanism by increasing the number of working branches of the drive belt.

The problem is achieved in that in a reversing mechanism for converting rotational motion into translational motion, comprising a housing, slide guides, a slider mounted on axes in the housing, parasitic pulleys, two deflecting pulleys mounted on axes in the slide, the first and second differential pulleys mounted on shafts in the housing and connected by a mechanical transmission of rotation with a reversible drive, an endless belt covering spurious, deflecting and differential pulleys located in such a way that in The legs of the belt covering the deflection pulleys mounted on the slider are parallel to each other, with each belt branch interacting with one of the differential pulleys, and the product of the ratio of the diameters of the differential pulleys and the gear ratio of the mechanical transmission of rotation has a value other than 1, additionally on the axes in the body and slider are equipped with two deflecting pulleys, covering which the belt forms two additional loops with parallel branches;

- two deflecting pulleys mounted on axes in the housing are connected with a mechanical transmission of rotation while ensuring that the condition

where D ₁ , D ₂ are the diameters of the first and second differential pulleys; D _a1 , D _a2 - the diameters of the additional pulleys mounted on the axles in the housing and associated with the mechanical transmission of rotation; i _{1, a1} , i _{1, a2} - gear ratio of the mechanical transmission of rotation, connecting the first differential pulley and additional pulleys, respectively; i _1,2 is the gear ratio of the mechanical transmission of rotation connecting the first and second differential pulleys;

- deflecting pulleys mounted on opposite ends of the equal-arm levers pivotally connected to the slider.

New in the proposed solution is that in the known reversing mechanism for converting rotational motion into translational motion, two deflecting pulleys are additionally installed on the axes in the housing and slider, encompassing which, the belt forms two additional loops with parallel branches;

- two deflecting pulleys mounted on the axes of the housing are connected with a mechanical transmission of rotation while ensuring the fulfillment of the condition

where D ₁ , D ₂ are the diameters of the first and second differential pulleys; D _a1 , D _a2 - the diameters of the additional pulleys mounted on the axles in the housing and associated with the mechanical transmission of rotation; i _{1, a1} , i _{1, a2} - gear ratio of the mechanical transmission of rotation, connecting the first differential pulley and additional pulleys, respectively; i _1,2 is the gear ratio of the mechanical transmission of rotation connecting the first and second differential pulleys;

- deflecting pulleys mounted on opposite ends of the equal-arm levers pivotally connected to the slider.

In FIG. 1 shows a frontal projection of the proposed device according to claim 1;

in FIG. 2 is a top view of the proposed device according to claim 1;

in FIG. 3 is an isometric view showing the arrangement of drive belts and pulleys of a device according to claim 1;

in FIG. 4 - frontal projection of the proposed device according to p. 2;

in FIG. 5 is a top view of the proposed device according to p. 2;

in FIG. 6 is an isometric view showing the arrangement of drive belts and pulleys of a device according to claim 2;

in FIG. 7 is a top view of the proposed device according to p. 3.

The proposed device consists of a base 1, straight guides 2 of the slider 3. On the base 1 is fixed to the housing 4.

Shafts 5 and 6 with differential pulleys 7 and 8 are located in the housing 4. The shafts 5 and 6 are connected by a mechanical transmission of rotation with a gear ratio i _1,2 . In this example implementation of the device, a mechanical transmission is a transmission with a toothed belt 9, covering pulleys 10, 11, rigidly connected to shafts 5 and 6, respectively.

On the opposite sides of the slider 3, the deflecting pulleys 13, 14, 15 and 16 are installed on the axles 12. On the base 1, the axes 17 of the deflecting pulleys 18 and 19 are installed. The endless timing belt 20, covering the deflecting pulleys 18, 19, the deflecting pulleys 13-16 and differential pulleys 7, 8 form four loops with parallel branches.

The first loop is formed by parallel branches 21 and 22 of the belt 20 extending from the differential pulley 7 to the deflecting pulley 13, and then to the deflecting pulley 18.

The second loop is formed by parallel branches 23 and 24 of the belt 20 extending from the deflecting pulley 18 to the deflecting pulley 14, and then to the differential pulley 8.

To increase the angle of coverage of differential pulleys 7, 8 with a toothed belt 20, parasitic pulleys 25, 26 and 27, 28 are mounted on axles 29 in the housing 4.

The third and fourth loops are formed respectively by the branches 30, 31 and 32, 33 of the toothed belt 20, sequentially covering the differential pulley 8, deflecting pulleys 15, 19, 16 and the differential pulley 7.

The operability of the mechanism is ensured by various peripheral speeds of rotation of the differential pulleys 7 and 8. For this, it is necessary that the product of the ratio of the diameters of the differential pulleys 7 and 8 to the gear ratio of the mechanical transmission of rotation be different from unity, which is achieved when the condition

where i _1,2 is the gear ratio of the mechanical transmission of rotation connecting the first and second differential pulleys and made, for example, in the form of a transmission with a toothed belt 9, covering the pulleys 10, 11.

When performing the device according to claim 2 (Fig. 4-6), the deflecting pulleys 18 and 19 are connected to a mechanical transmission of rotation, while ensuring that the condition

where D ₁ , D ₂ are the diameters of the differential pulleys 7 and 8; D _a1 , D _a2 - the diameters of the deflecting pulleys 18 and 19 associated with the mechanical transmission of rotation; i _{1, a1} , i _{1, a2} - gear ratio of the mechanical transmission of rotation connecting, respectively, the first differential pulley 7 and the additional pulley 18, as well as pulleys 7 and 19; i _1,2 - gear ratio of the mechanical transmission of rotation connecting the first and second differential pulleys.

In the given example of implementation, the mechanical transmission is made in the form of a transmission with a toothed belt 9, covering pulleys 10, 34, 11 and 35. The pulley 34 is rigidly connected to the deflecting pulley 18, and the pulley 35 with the deflecting pulley 19.

This design of the mechanism allows to reduce the uneven tension of the loops of the belt 20, arising due to friction losses in the bearings of the deflecting pulleys 18, 19, as well as deflecting pulleys 13, 14, 15, 16 and spurious pulleys 25, 26, 27, 28.

To reduce the unevenness of the tension of the belt loops when the gear ratio of the mechanism fluctuates due to the manufacturing errors of differential pulleys 7, 8, pulleys 10, 11, 34 and 35 and the teeth of the belts 9, 20 in the device according to claim 3, equal arms levers 36, 37 (p. 3 of the claims, Fig. 7). The levers 36 and 37 are mounted on the slider 3 in the hinges 38 and 39, respectively. While the deflecting pulleys 13 and 14 are installed at opposite ends of the lever 36, and the deflecting pulleys 15, 16 are at the opposite ends of the lever 37.

The device operates as follows.

Rotation with a frequency of ω ₁ , which is periodically reversed, is transmitted to the shaft 5 and the differential pulley 7 and the pulley 10 rigidly connected to it. The pulley 7 drives the belt 20, and the pulley 10 - the belt 9. The belt 9 transmits rotation to the pulleys 11 and 8, rigidly interconnected by the shaft 6. The belt 20 drives the pulleys 18, 19, deflecting pulleys 13, 14, 15, 16 and spurious pulleys 25, 26, 27, 28.

The difference in peripheral speeds of the pulleys 7 and 8 causes a change in the size of the loops formed by branches 21, 22, 23, 24, as well as loops formed by branches 30, 31, 32 and 33.

The deflecting pulleys 13, 14, 15, 16, rotate on the axes 12 and report the progressive movement of the slider 3. The speed of movement of the slider 3 can be determined by the formula

In the execution of the mechanism, which allows to reduce the effect of friction losses on the uniformity of the tension of the branches 21, 22, 23, 24 and 30, 31, 32, 33 of the belt 20, the belt 9 transmits rotation to additional pulleys 34 and 35, pairwise rigidly connected to the pulleys 18 and 19, which in this case perform the function of auxiliary differential pulleys. In this version of the mechanism, it is important that condition (1) is met, which ensures pairwise equality of loops 21, 22 and 23, 24, as well as 30, 31 and 32, 33. This condition is determined by the equality of the linear speeds of the axes 12 of the pulleys 13 and 14. Its conclusion is given below .

For all versions of the mechanism (paragraphs 1-3 of the formula), the linear speeds of the axes 12 of the pulleys 13 and 14 are determined by the equations

Equating the speeds v ₁ and v ₂ , we obtain an equation relating the angular speeds of the pulleys 7, 8, 18 and 19

We write the equations for the gear ratios of the angular speeds of the pulleys 8 and 18 to the angular speed of the driving pulley 7

The gear ratio i _{1, a1p} is the gear ratio of the transmission formed by the branches of the belt 21, 22.

Substituting equations (3) into equations (2), we obtain the following expression relating the diameters of pulleys 7, 8, 18, 19, and the gear ratios between them

When the device according to claim 2 of the formula is executed, a transmission mechanism is added to the design, connecting the differential pulley 7 and deflecting the pulley 18. The mechanism of claim 2, the gear ratio of the transmission formed by the branches of the belt 21, 22 to ensure operability should be equal to the gear relation of mechanical transmission of rotation

Substituting equality (5) in (4), we obtain the condition for ensuring the operability (1) of the mechanism according to claim 2 of the claims.

The equations for the branches of the belt 30, 31, 32 and 33 are obtained on the basis of similar reasoning.

For gear pulleys, equation (2) can be converted using expressions relating the modulus, diameter and number of pulley teeth

where m is the transmission module, z ₁ , z _a1 , z ₂ are the number of teeth of the pulleys 7, 18 and 8, respectively. For gears with a toothed belt, the number of teeth of the pulley 18 can be defined as

For example, consider a transmission with the following parameters: z ₁ = 22, z ₂ = 26, i ₁₂ = 1, i _{1, a1} = 1. Calculation according to the formula (3) gives the value

When 3 equal arms of 36 and 37 are fastened to the slider, the uniformity of the distribution of forces between the loaded branches of the belt 20 is increased. When the mechanism for manufacturing errors of its parts leads to fluctuations in the lengths of the loops formed by the branches 21, 22 and 23, 24, as well as 30, 31 and 32 , 33 of the toothed belt 20. Due to the rotation of the equal-arm levers 36 and 37 by a certain angle, the tension forces of the indicated branches of the belt 20 are aligned.

The use of the proposed reversible mechanism will increase its rigidity by increasing the number of working branches of the drive belt, as well as reduce the unevenness of the stroke by providing a significant gear ratio between the input and output link.

Claims (4)

1. Reversible mechanism for converting rotational motion into translational motion, comprising a housing, slider guides, a slider, parasitic pulleys mounted on axes in the housing, two deflecting pulleys mounted on axes in the slider, first and second differential pulleys mounted on shafts in the housing and connected mechanical transmission of rotation with a reversible drive, an endless belt covering spurious, deflecting and differential pulleys arranged in such a way that the branches of the belt covering deflecting pulleys The s installed on the slider are parallel to each other, with each belt branch interacting with one of the differential pulleys, and the product of the ratio of the diameters of the differential pulleys and the gear ratio of the mechanical transmission of rotation has a value other than 1, characterized in that it additionally on the axes in the housing and on the slider are installed two deflecting pulleys, covering which, the belt forms additional loops with parallel branches. 2. The reversing mechanism according to claim 1, characterized in that the two deflecting pulleys mounted on the axes in the housing are connected with a mechanical transmission of rotation while ensuring that the condition

where D ₁ , D ₂ are the diameters of the first and second differential pulleys; D _a1 , D _a2 - diameters of additional deflecting pulleys mounted on axes in the housing and associated with a mechanical transmission of rotation; i _{1, a1} , i _{1, a2} - gear ratio of the mechanical transmission of rotation, connecting the first differential pulley and additional pulleys, respectively; i _1,2 - gear ratio of the mechanical transmission of rotation connecting the first and second differential pulleys. 3. The reversing mechanism according to claim 2, characterized in that the deflecting pulleys are mounted on opposite ends of the equal-arm levers pivotally connected to the slider,

where D ₁ , D ₂ are the diameters of the first and second differential pulleys; D _a1 , D _a2 - the diameters of the additional pulleys associated with the mechanical transmission of rotation; i _{1, a1} , i _{1, a2} - gear ratio of the mechanical transmission of rotation, connecting the first differential pulley and additional pulleys, respectively; i _1,2 - gear ratio of the mechanical transmission of rotation connecting the first and second differential pulleys. 4. The reversing mechanism according to claim 2, characterized in that the deflecting pulleys are mounted on opposite ends of the equal-arm levers pivotally connected to the slider.

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