JP4815787B2 - Machine tool feeder - Google Patents

Description

  The present invention relates to a feed device that uses a slider, a table, or the like of a machine tool as a moving body, and more particularly to an improvement of a feed device that employs a linear motor as a feed drive source.

  As a feeding device for a machine tool such as an electric discharge machine, one that uses a linear motor as a drive source is proposed in Patent Document 1 and the like. In these feeders, a synchronous linear motor (combination of a permanent magnet and a coil slider) is generally used for reasons such as good positioning accuracy, low heat generation, and stability of magnetic attractive force. In the case of the synchronous type, the magnetic attractive force between the permanent magnet and the coil slider is as large as 3 to 4 times the maximum thrust. Therefore, the linear type has a function to keep the gap between the permanent magnet and the coil slider constant against the magnetic attractive force. A large load is always applied to the guide (direct acting guide member).

  For example, in a linear motor drive feeder with a thrust of about 15 kN, which is often used in cutting and grinding, not only a load of 50 kN is applied to the linear guide, but also a linear motor with a thrust of about 15 kN is driven. Since the column of the feeding device has a mass of about 1 ton, in a feeding device composed of a combination of a rotary motor and a ball screw mechanism which has been used for a long time, a linear guide is applied where a load of about 10 kN is applied to the linear guide. Then, 10 kN + 50 kN = 60 kN, which is 6 times as much load.

The life of the linear guide is inversely proportional to the cube of the load received by itself (however, when the rolling element is a ball and when the rolling element is a roller, it is inversely proportional to the 3.3 power) Thus, when a load of 6 times is applied, the lifetime becomes a lifetime of 1/6 ³ = 1/216.

As a countermeasure against such a problem, for example, as described in Patent Document 2, two sets of linear motors having the same specifications are arranged so as to oppose each other, and the magnetic attraction forces are canceled out. The thing considered so that a suction | attraction force is not added is proposed.
JP-A-8-309620 (FIG. 1) JP 2002-346844 A (FIG. 2)

  However, in the conventional technique as described in Patent Document 2, the load burden (load weight) of the linear guide based on the magnetic attractive force can be greatly reduced, but the structure is not provided for the layout in which the linear motors are opposed to each other. Since the weight of the structure that has become larger and heavier is added to the linear guide as it is, it is highly possible that the effect of miniaturizing the linear guide and extending its life cannot be obtained as expected.

  The present invention has been made by paying attention to such a problem, and it is intended to provide a feeding device that is designed so that the load weight of the linear guide can be significantly reduced while assuming a structure in which linear motors are arranged to face each other. It is what.

According to the first aspect of the present invention, in the feeding device that applies a horizontal linear feed to the movable body guided and supported by the support body, the movable body has a web extending in a skirt shape downward from the center of the lower surface. While being formed as a T-shaped cross-sectional deformation, a pair of movable side vertical wall surfaces are formed on both sides of the web, which are inclined at a predetermined angle with respect to the vertical line and are symmetric with respect to the vertical line. The movable body side web is formed with a substantially concave cross section, and the movable side vertical wall surfaces are parallel to and opposed to the fixed side vertical wall surfaces. Forms a dovetail guide mechanism.

In addition, a thrust in the feed direction is generated based on the magnetic attraction force between a pair of movable-side vertical wall surfaces at the left and right symmetrical positions on the movable body side and the respective fixed-side vertical wall surfaces on the support side. And a linear moving guide member positioned above and below the linear motor so that the linear motor is individually disposed so as to be bilaterally symmetric, and each linear motor generates a floating force of the moving body relative to the support. In addition to the generation of thrust based on the magnetic attraction force of each linear motor, the levitation force is generated on the moving body based on the magnetic attraction force of the linear motor. It is characterized by being.

  In addition, as a moving body in the machine tool, a sliding saddle, a ram, a table, a column, a head, a quill and the like are assumed.

  Accordingly, in the present invention, two sets of linear motors are arranged opposite to each other to cancel the magnetic attraction forces, and the magnetic attraction force is not applied to the linear guide. It is the same as that.

  In addition, in the present invention, the weight of the moving body is offset by lifting the moving body from the support with the levitation force generating means, and the load weight applied to the linear guide member is substantially close to zero. It can be reduced to the state.

  According to the first aspect of the present invention, the load weight of the linear guide member that is interposed between the support body and the movable body forming the feeding device can be remarkably reduced. There is an effect that the guide member itself can be miniaturized and its life can be extended. In particular, the stick-slip phenomenon at the time of slow speed movement, which has been a problem with a linear motor-driven feeding device, is eliminated, and high-precision dynamic positioning accuracy can be secured over the entire range from ultra-low speed to ultra-high speed.

  FIG. 1 is a view showing a more specific embodiment of a feeding apparatus according to the present invention.

  In this feeding device, a base 1 as a support, a table 2 as a movable body guided and supported by the base 1 and capable of linearly moving in the horizontal direction, and a column 3 mounted on the table 2 are provided. The column 3 is provided with, for example, a processing spindle 4.

  These base 1, table 2, column 3, and the like have a symmetrical shape with a vertical line L passing through the axis of the main shaft 4 as the center of symmetry, and a linear motion guide between the base 1 and the table 3. A pair of left and right linear guides 5 are interposed as members, and a synchronous linear motor 6 that functions as a drive source for feeding the table 2 is also symmetrically disposed. The synchronous linear motor 6 has a constant magnetic attraction force that attracts the coil and the magnet regardless of whether or not the motor 6 itself is energized and the amount of energization (= generated thrust).

  More specifically, the table 2 is formed as a substantially deformed T-shaped cross section in which the web 7 extends downwardly from the center of the lower surface in a skirt shape, while the base 1 has a cross section to receive the web 7. The slide guide mechanism is a so-called dovetail guide mechanism. Of the movable side vertical wall surfaces 7a and 7b, which are both side surfaces of the web 7, and the fixed side vertical wall surfaces 1a and 1b on the base 1 side facing each other, the vertical wall surfaces 7a and 1a and 7b and 1b are parallel to each other. However, the vertical wall surfaces 7a, 1a and 7b, 1b are inclined by a predetermined angle α with respect to the vertical line L so as to be symmetrical, and between the vertical wall surfaces 7a, 1a and 7b, 1b. The linear motor 6 and the linear guide 5 having the same specifications are disposed in each case.

  Here, the pair of left and right linear motors 6 have their coil sliders (movers) 6a fixed to the movable side vertical wall surfaces 7a and 7b and permanent magnets (stator) 6b fixed to the fixed side vertical wall surfaces 1a and 1b, respectively. For each linear motor 6, a predetermined gap of the same amount is provided between the coil slider 6a and the permanent magnet 6b. When the weight on the movable side of the table 2, the column 3 and the coil slider 6a is W and the magnetic attraction force per set of the linear motor 6 is C, the angle α is set so as to satisfy the following expression (1). Set.

α = sin ⁻¹ (W / (2 × C)) (1)
The relative positional relationship between the coil slider 6a and the permanent magnet 6b forming each linear motor 6 may be reversed. As is well known, there is a correlation between the size of the gap and the magnitude of the magnetic attractive force C, and a larger magnetic attractive force acts as the gap is smaller.

  Therefore, according to the feeding device configured as described above, by performing energization control of each linear motor 6, a predetermined feed is given to the table 2 by the thrust based on the magnetic attractive force C generated by each linear motor 6. Thus, the table 2 travels linearly in a manner guided by the base 1.

  In this case, since the pair of left and right linear motors 6 have the same specifications, the magnetic attractive force C generated by each linear motor 6 is the same and the direction of action is opposite, so both linear motors 6 are generated. The magnetic attractive forces C cancel each other, so that the load weight based on the magnetic attractive force C is not applied to each linear guide 5 and the burden on each linear guide 5 is reduced.

  In addition, since each linear motor 6 is arranged at an angle α, a levitation force F that causes the table 2 to float from the base 1 is generated as a component of the magnetic attraction force C generated by each linear motor 6. In addition, as described above, the angle α is set in consideration of the weight of the table 2, the column 3, and the like, so that the weight of the table 2 and the like can be offset by the levitation force F. it can. Thereby, the pair of left and right linear motors 6 also have a function as a levitation force generating means.

  As a result, the load weight applied to each linear guide 5 can be made as close to zero as possible, and as described above, “the life of the linear guide is inversely proportional to the cube of the load that the linear guide itself receives”. If the above definition is applied, it is possible to make the calculation life of each linear guide 5 infinite.

  Actually, since there is a load fluctuation at the time of acceleration / deceleration, the load applied to the linear guide 5 may be in the plus (+) direction or minus (−) direction. Compared to the total weight on the movable side of the coil slider 6a and the like, this is a very small amount and causes little problem. In other words, the load weight of the linear guide 5 is substantially close to zero when stationary, and only a load weight of about 1 kN or less during acceleration / deceleration.

  Since the load weight applied to the linear guide 5 can be remarkably reduced in this manner, the size of the linear guide 5 can be significantly reduced, and the initial cost and the running cost can be reduced by extending the service life. become.

  Further, the rolling resistance of the linear guide 5 is nothing but the load W received by the linear guide 5 multiplied by the friction coefficient μ of the linear guide 5, so that the load W received by the linear guide 5 is made substantially zero. The slide guide mechanism with ultra-low friction can be established, and the stick-slip phenomenon at the slow speed movement, which has been a problem with linear motors, can be resolved. Dynamic positioning accuracy can be ensured.

Cross-sectional explanatory drawing which shows preferable embodiment of the feeder which concerns on this invention.

Explanation of symbols

1 ... Base (support)
1a, 1b ... fixed side vertical wall surface 2 ... table (moving body)
5… Linear guide (Direct acting guide member)
6. Linear motor (levitation force generating means)
6a ... Coil slider (movable element)
6b ... Permanent magnet (stator)
7a, 7b ... movable side vertical wall
8 ... Magnet unit (levitation force generating means)

Claims (1)

In a feeding device that gives a linear feed in a horizontal direction to a moving body guided and supported by a support,
The moving body is formed as a T-shaped cross section having a web extending in a skirt shape downward from the center of the lower surface, and both sides of the web are inclined at a predetermined angle with respect to a vertical line. While a pair of symmetrical movable vertical wall surfaces are formed,
The support body is formed as a substantially concave cross-sectional shape for receiving the web on the moving body side, and is formed with a fixed-side vertical wall surface that is parallel to and faces each movable-side vertical wall surface,
These supports and moving bodies have a groove-type guide mechanism,
Between the respective fixed-side longitudinal wall surface of the support side opposite thereto and a pair of movable vertical wall surface on the left and right symmetrical positions of the moving body side, a linear motor for generating thrust in the feed direction on the basis of the magnetic attraction force In addition, with the linear motion type guide members positioned above and below the linear motor, they are disposed separately so as to be bilaterally symmetric,
Each of the linear motors also has a function as a moving body levitation force generating means for generating a levitation force of the moving body with respect to the support, and in parallel with the thrust generation based on the magnetic attraction force of each linear motor, A machine tool feeding device , wherein a floating force is generated in a moving body based on a magnetic attractive force .

Images