JPH1190822A - Work rest device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent center dislocation of the rotational center of a headstock with respect to the axis of the part of crank shaft to be processed, when the part is ground by a grinder. SOLUTION: A work rest device to support the part to be processed of a work 4 during the grinding process includes a first 12 and a second supporting arm member 13 to support the work in separate positions in circumferential direction in such a way as opposing to the grinding resistance of a grinding wheel 7 and a first and second driving means 16, 15; 18, 17 to drive the supporting arm members separately and exert a press supporting force to the work, wherein the amount of deformation caused by the grinding resistance of each supporting arm member is detected by strain gauges 19 and 20, and on the basis of the obtained amounts of deformation, the driving means are controlled by controlling means 21-26 so that the resultant vector of the press supporting forces by the supporting arm members has the same size as the vector of the grinding resistance, provided that the directions are opposite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work rest device for supporting a machined portion of a long work such as an engine crankshaft when grinding the outer peripheral surface of the work.

[0002]

2. Description of the Related Art When grinding the outer peripheral surface of a work such as a crankshaft or the like, both ends of the crankshaft are arranged between two opposed headstocks of a grinder so that the center of the machined portion is aligned with the center of the spindle. The part is supported and fixed, and the rotating grinding wheel is brought into contact with the area to be ground to perform the grinding. In this grinding process, the grinding shaft may bend due to the grinding resistance of the grinding wheel, and the rotation center of both headstocks may be displaced from the shaft center of the processed portion of the crankshaft, thereby reducing grinding accuracy. And a work rest that supports the processed portion of the crankshaft by abutting against the outer peripheral surface of the processed portion of the crankshaft so as to face the same.

A conventional example of such a work rest is disclosed in Japanese Utility Model Laid-Open Publication No. 4-109848, etc. The work rest disclosed in the publication discloses a work rest at a constant pressure during grinding. It is configured to urge the rest against the processed portion.

[0004]

The work rest used for grinding the outer peripheral surface of the crankshaft, that is, the pin portion and the journal portion, is arranged in a narrow region between the counterweights of the crankshaft.
There is a limit in rigidity due to the dimensional restriction, and the work rest may be deformed or the amount of deformation may be changed due to the grinding resistance during grinding or the fluctuation of the grinding resistance.

Therefore, in the case where the work rest is urged toward the work with a constant pressure during the grinding process as in the above-mentioned prior art, a part of the constant pressing force is reduced due to the sliding resistance of the driving portion. In some cases, the required supporting force may not be obtained at the position of the work due to the consumption of the work, and the support cannot follow the variation of the pushing allowance due to the fluctuation of the grinding resistance or the temperature change. As a result, the center of rotation of the headstock and the axis of the work are misaligned, and the grinding accuracy is reduced.

The present invention has been achieved in view of the above-mentioned problems of the prior art. It is an object of the present invention to provide a method in which a work rest supporting a work is deformed or deformed due to a grinding resistance or a change in the grinding resistance. Provided is a work rest device that can control to follow a change in grinding resistance and always obtain an optimal pressing support force, even if the pressing amount changes due to a change in the deformation amount. Is to do.

[0007]

According to a first aspect of the present invention, there is provided a work rest device which supports both ends of a long workpiece and grinds the outer peripheral surface of the workpiece by a grinding wheel while rotating the workpiece. What is claimed is: 1. A workrest device for supporting a processing portion of a work when processing, wherein a first support arm member and a first support arm member for supporting the work at different positions in a circumferential direction so as to oppose a grinding resistance of the grinding wheel. 2 support arm members,
A first drive unit and a second drive unit that separately drive the first support arm member and the second support arm member to exert a pressing support force on the work; and the first support arm member and the second support arm member, respectively. A first detecting means and a second detecting means for detecting an amount of deformation due to a grinding resistance of the first and second supporting arm members based on output information of the first and second detecting means. The first vector is set so that the resultant vector of the pressing support force and the vector of the grinding force are opposite to each other with the same magnitude.
And a control means for controlling the driving means and the second driving means.

According to a second aspect of the present invention, in the work rest device, the first detecting means and the second detecting means comprise strain gauges provided on the first supporting arm member and the second supporting arm member. The control means controls the first drive means and the second drive means in accordance with the amount of strain of the strain gauge.

According to a third aspect of the present invention, in the work rest device, the ratio of the pressing support force of the first support arm member to the pressing support force of the second support arm member is always constant. As described above, the first driving unit and the second driving unit are controlled.

[0010]

According to the work rest device of the first aspect of the present invention, the first support arm member and the second support arm member for supporting the work during the grinding process due to the grinding resistance of the grinding wheel or the fluctuation of the grinding resistance. When the supporting arm member is deformed or the amount of deformation is changed, the first detecting means and the second detecting means
The detecting means detects the deformation amount of the first support arm member and the second support arm member, and based on the detected information,
The control means controls the first driving means and the second driving means,
The combined vector of the pressing support force of each of the first support arm member and the second support arm member is always parallel to the vector of the grinding resistance and has the same magnitude so as to be in the opposite direction.

Therefore, the center of rotation of the headstock of the grinding machine and the axis of the machined portion of the workpiece are supported so as to suppress misalignment, whereby the grinding accuracy can be improved.

In addition, since the above-mentioned misalignment is suppressed, the grinding process can be simplified.
Shortening of the grinding time can be achieved.

According to the work rest device of the second aspect of the present invention, the first detecting means and the second detecting means for detecting the deformation amounts of the first support arm member and the second support arm member due to the grinding resistance, respectively, Since the strain gauges provided on each of the first support arm member and the second support arm member are employed, the deformation amount of the first support arm member and the second support arm member can be easily detected with a simple structure. .

The control means controls the first drive means and the second drive means according to the amount of strain of each strain gauge provided on the first support arm member and the second support arm member.

That is, since the strain amount of each strain gauge corresponds to the pressing support force exerted on the work by each of the first support arm member and the second support arm member, the strain amount of each strain gauge is fed back. ,
In order for the ratio of each of these strain amounts to be a predetermined value,
By controlling the first drive means and the second drive means, the first drive means
The ratio is adjusted so that the ratio between the pressing support force of the support arm member and the pressing support force of the second support arm member is constant.

Thus, the misalignment between the rotation center of the headstock and the axis of the machined portion of the work is suppressed by a simple structure, thereby improving the grinding accuracy and simplifying the structure. it can.

According to the work rest device of the third aspect of the present invention, the first drive means and the second drive means are controlled by the control means, and the pressing support force of the first support arm member and the second support arm member. Is adjusted so that the ratio to the pressing support force by the constant is always constant.

That is, since the direction of the vector of the grinding force by the grinding wheel is always constant, the composite vector of the two pressing and supporting forces is parallel to the vector of the grinding force only by keeping the ratio of the respective pressing and supporting forces constant. And can be adjusted to have the same size.

As a result, misalignment between the center of rotation of the headstock and the center of the axis of the processed portion of the work can be suppressed, and the grinding accuracy can be improved.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a plan view showing a grinding machine provided with a work rest device according to the present invention. In this grinding machine, as shown in FIG. 1, a headstock 2 and a headstock 3 are arranged on a slide base (not shown) provided on the upper surface of a base 1 so as to face each other. Chucks 5 and 6 for supporting and fixing both ends of a crankshaft 4 as a work are provided at opposite ends of the tables 2 and 3. Both ends of the crankshaft 4 are supported by the headstocks 2 and 3 via the chucks 5 and 6 such that the axis center of the processed portion coincides with the center of the spindle. And the headstocks 2 and 3 are
With the crankshaft 4 supported, the slide base can be moved in the X-axis direction (the left-right direction in the drawing).

In the Y-axis direction (vertical direction in the drawing) orthogonal to the axial direction of the crankshaft 4, the grinding wheel 7 and the work rest device 10 are sandwiched by the crankshaft 4.
Are arranged so as to face each other. The grinding wheel 7 is
The grindstone 8 is rotatably supported by the grindstone 8.
Are supported on a slide base 9 so that the grinding wheel 7 can move forward and backward with respect to the crankshaft 4.

On the other hand, the workrest device 10 is supported on a slide base 11 so as to be able to advance and retreat with respect to the crankshaft 4, and the first support arm member 12 and the second support arm constituting the workrest device 10 are provided. Arm member 13 (only the first support arm member 12 is shown in FIG. 1)
Can be passed or separated from the outer peripheral surface of the journal portion 4a or the pin portion 4b as a processed portion through the space between the counterweights 4c of the crankshaft 4.

Next, the work rest device 10 will be described in detail.

As shown in FIG. 2, the work rest device 10 has a first shoe 12a carrying a first shoe 12a abutting on a processed portion of the crankshaft 4 as a work, that is, the outer peripheral surface of the journal portion 4a or the pin portion 4b. 1 support arm member 12 and the first shoe 12 in the circumferential direction.
and a second support arm member 13 that carries a second shoe 13a that similarly contacts the outer peripheral surface at a position different from a.

The first support arm member 12 is
While being swingably pivotally supported around a support shaft 14, the spring 27 is biased to rotate in a counterclockwise times fairly, with respect to the end portion 12b, and reciprocates in the direction of arrow L ₁ plunger 15 ends are in contact with each other. Also,
The plunger 15 is reciprocated by a drive motor 16 via a feed screw (not shown) or the like.

A first drive means for driving the first support arm member 12 by the drive motor 16, the feed screw, the plunger 15 and the like to adjust the pressing support force on the workpiece.

On the other hand, the second support arm member 13 is swingably pivotally supported around a first support arm member 12 in the same manner as the support shaft 14, relative to the end 13b, in the direction of arrow L ₂ A reciprocating connecting rod 17 is attached. The connecting rod 17 is reciprocated by a driving motor 18 via a feed screw, a lever, and the like (not shown).

The drive motor 18, feed screw, lever,
A second driving unit that drives the second support arm member 13 by the connecting rod 17 and the like to adjust the pressing support force on the workpiece is configured.

According to the above configuration, when the plunger 15 moves rightward in the drawing by the operation of the drive motor 16, the first support arm member 12 rotates clockwise in the drawing, and the first shoe 12a Processed part 4a,
When the connecting rod 17 is moved leftward in the figure by the operation of the drive motor 18, the second support arm member 13 rotates counterclockwise in the figure, The two shoes 13a exert a pressing support force on the machined portions 4a, 4b of the crankshaft 4 from substantially below.

In order to reduce the respective pressing and supporting forces, the plunger 15 and the first support arm member 12, the connecting rod 17 and the second support arm member 13 may be respectively operated in the opposite directions to the above operations. .

Further, strain gauges 19 as first detection means for detecting the amount of deformation of the first support arm member 12 are provided on both left and right opposite sides of the first support arm member 12.
Are provided on both upper and lower opposing surfaces of the second support arm member 13, and strain gauges 20 are provided as second detection means for detecting the amount of deformation of the second support arm member. And these strain gauges 19, 2
Numeral 0 is connected via a wiring 21 to a measuring device 22 for measuring the respective amounts of strain, and further, an A / D converter 23, a computing device 24, a sequencer 25, and an amplifier 26 are sequentially connected.

The measuring device 22, the A / D converter 23, the computing device 24, the sequencer 25, the amplifier 26 and the like make up the first detecting means and the second detecting means, that is, the strain gauges 19 and 2.
Based on the strain amount of 0, the combined vector of the pressing support forces of the first support arm member 12 and the second support arm member 13 is always parallel to the vector of the grinding resistance by the grinding wheel 7 and has the same magnitude. Control means for controlling the first driving means and the second driving means in the opposite direction is configured.

According to the above configuration, when the first support arm member 12 and the second support arm member 13 are deformed by the grinding resistance and change occurs in the strain gauges 19 and 20, the measuring device 22 measures the amount of strain. The obtained measured value is converted into a digital signal by the A / D converter 23, and the converted digital signal is input to the calculator 24 to perform a predetermined calculation, and the obtained calculated value is sent to the sequencer 25. The output signal from the amplifier 26 is controlled based on the output signal from the sequencer 25, and the drive motors 16 and 18 are driven so that a desired pressing support force is obtained.

That is, the deformation amount of the first support arm member 12 and the second support arm member 13 that directly support the work (crankshaft), that is, the strain gauges 19 and 20
Since the amount of change corresponds to the amount of change in the pressing support force of each of the support arm members 12, 13, the strain gauges 19,
By monitoring the amount of change of each of the 20 and feedback-controlling the amount of change of each of the 20 to a predetermined ratio,
The ratio between the pressing support force of the first support arm member 12 and the pressing support force of the second support arm member can be maintained at a predetermined value, for example, an initial setting value.

Next, the relationship between the grinding resistance of the grinding wheel 7 and the pressing support force of the first support arm member 12 and the second support arm member 13 will be described. As shown in FIG. 3, when grinding is performed by bringing the grinding wheel 7 into contact with the work (crankshaft) 4, assuming that a tangential component force of the grinding resistance F is Ft and a normal component force is Fn. Component F
t and Fn are represented by the following equations (1) and (2).

Ft = Pm · (Sc + μS) (1) Fn = Pm · S (2) where Sc is the cross-sectional area of the grinding groove, and S is the direction normal to the contact portion between the grinding blade and the work. , Μ: coefficient of friction between the grinding blade and the work, Pm: plastic flow pressure of the work.

From the above equations (1) and (2), the following equation (3) is derived.

[0039]

As can be understood from the above equation (3), when workpieces of the same material are ground by the same grinding wheel 7, the direction of the vector becomes constant even if the magnitude of the grinding resistance F changes. .

On the other hand, the first shoe 12a of the first support arm member 12 and the second shoe 13 of the second support arm member 13
When a supports the work 4 and the pressing support forces in the respective normal directions are Fu and Fd, the resultant vector of the pressing support forces Fu and Fd is Fr.

Accordingly, the magnitude of the pressing support force Fu by the first support arm member 12 and the pressing support force Fd by the second support arm member 13 are adjusted, and the resultant vector Fr is adjusted.
By controlling the size and direction of
r can be made parallel to and the same size as the grinding resistance F, whereby the bending of the work 4 due to the grinding resistance F is suppressed, and the rotation center of the headstocks 2 and 3 and the work 4 The misalignment between the machined portions 4a and 4b and the center of the shaft is made as close to zero as possible.

Next, the operation of the present apparatus will be described. First, as shown in FIG. 4, a precision master work 4 'is placed between the headstocks 2 and 3 so that the center of the machined portion of the master work 4' is located on the headstocks 2 and 3.
The grinding wheel 7 is brought into contact with the master work 4 'in a state where the grinding wheel 7 is not in contact with the master work 4', and the master work 4 'is rotated. Then, the pressure supporting force of the first support arm member 12 and the second support arm member 13 is adjusted so that the needle deflection of the dial gauge 30 becomes zero, and the amount of change of the strain gauges 19 and 20 at that time is detected. Then, the detected value is stored in the computing unit 24 as an initial value.

Subsequently, the work 4 is mounted, and the grinding wheel 7 is brought into contact with the work 4 to start grinding. Then, a load is applied to each of the first support arm member 12 and the second support arm member 13 by the grinding resistance F generated in the grinding.

With this load, each strain gauge 1
Since 9 and 20 change, the amount of change is measured by the measuring device 22.

Subsequently, the obtained measured value is converted to an A / D converter 2
The arithmetic unit 24 performs a predetermined operation based on the digital amount, and the obtained operation result is input to the sequencer 25 to control the output signal of the amplifier 26.

Then, the driving motors 16 and 18 are driven based on the output signal from the amplifier 26, and the pressing support force Fu by the first support arm member 12 and the second support arm member 1
3, the first support arm member 12 and the second support arm member 13 are adjusted so that the ratio with the pressing support force Fd becomes the same as the initial state.

By performing the above operations continuously during the grinding process, the misalignment between the rotation centers of the headstocks 2 and 3 and the axis centers of the processing portions 4a and 4b of the work 4 is adjusted so as to always approach zero. Thus, the roundness of the grinding process is improved.

In the grinding of the work (crankshaft) 4 as described above, as shown in FIG. 5, the feed rate is sequentially increased from the diameter before the grinding to the diameter of the final finish. Grinding processes such as reduced first feed, medium feed, finish feed, and spark-out with zero feed speed are employed.

In the case of using a conventional work rest device in such a grinding step, for example, a cutting allowance of 20 to 30 is used.
Although the finish feed process for obtaining roundness has been started just before μm, when the work rest device of the present invention is used, misalignment can be minimized, so that the finish feed process can be shortened. This allows
The entire grinding process can be shortened.

Also, instead of employing the above-described four-stage grinding process, the number of processes can be reduced and the grinding process can be simplified, so that the entire grinding process can be shortened.

In the embodiment described above, only the case where the crankshaft is used as the work has been described. However, the present invention is not limited to this, and can be applied to other long works.

Further, the drive motor 1 in the above embodiment
As the motors 6 and 18, a torque motor or a servo motor having an encoder may be used.

Further, in the above-described embodiment, the case where the strain gauge is employed as the detecting means for detecting the amount of deformation of the first support arm member 12 and the second support arm member 14 has been described. Instead, a configuration may be adopted in which a piezoelectric element or the like is adopted and the amount of change in the electromotive force is measured.

[Brief description of the drawings]

FIG. 1 is a plan view showing a grinding machine provided with a work rest device according to the present invention.

FIG. 2 is a configuration diagram showing one embodiment of a work rest device according to the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a grinding resistance by a grinding wheel and a pressing support force by a work rest device.

FIG. 4 is an explanatory diagram showing a state in which initialization is performed in the work rest device according to the present invention.

FIG. 5 is a diagram showing each stage of a grinding process when grinding a work.

[Explanation of symbols]

 2 Headstock 3 Headstock 4 Crankshaft (work) 4a Journal part (working part) 4b Pin part (working part) 4c Counterweight 5,6 Chuck 7 Grinding wheel 8 Grinding wheel stand 10 Workrest device 12 First support arm member 12a First shoe 12b End 13 Second support arm member 13a Second shoe 13b End 14 Support shaft 15 Plunger 16 Drive motor 17 Connecting rod 18 Drive motor 19 Strain gauge (first detection means) 20 Strain gauge (second detection means) ) 21 Wiring 22 Measuring device 23 A / D converter 24 Computing device 25 Sequencer 26 Amplifier 27 Spring

Claims (3)

[Claims] 1. A work rest device that supports both ends of a long work and supports a processed portion of the work when grinding the outer peripheral surface of the work with a grinding wheel while rotating the work. A first support arm member and a second support arm member for supporting the work at different positions in the circumferential direction so as to oppose the grinding resistance of the grinding wheel; and the first support arm member and the second support arm. A first driving unit and a second driving unit that separately drive members to exert a pressing support force on the work; and a first detecting unit that detects an amount of deformation of each of the first supporting arm member and the second supporting arm member due to a grinding resistance. Detection means and second detection means; and synthesis of respective pressing support forces by the first support arm member and the second support arm member based on output information of the first detection means and the second detection means. As vector and the vector of the grinding force are opposite in the same size with each other, work rest device being characterized in that and a control means for controlling said first drive means and second drive means. 2. The first detecting means and the second detecting means,
It comprises a strain gauge provided on the first support arm member and the second support arm member, and the control means controls the first drive means and the second drive means according to a strain amount of the strain gauge, The workrest device according to claim 1, wherein: 3. The first driving means and the second driving means such that a ratio between a pressing support force of the first support arm member and a pressing support force of the second support arm member is always constant. The workrest device according to claim 1, wherein the workrest device controls a driving unit.