JPH0347964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Conventionally, as shown in FIG. 1, a boring bar 2 is rotatably attached to a boring head 1 of a machine tool.
When drilling a deep hole into a workpiece (workpiece) 4 using the cutting tool 3, the distance from the boring head 1 to the processing point becomes large, causing the boring bar to bend due to the cutting reaction force F. In order to reduce the accuracy of drilling, a bearing device 5 is provided to support the tip of the boring bar during machining. Usually, the front and rear are supported by rolling bearings 7, respectively. 8 in Figure 1
1 is a bearing device main body, 9 is a workpiece mounting jig, 10 is a bed of a machine tool, and 1a is a feed unit of the boring head 1.

For this reason, it has the following drawbacks.

(a) In order for the boring bar 2 to rotate and slide into the support bush 6, a gap of about 10 to 15 microns is required between the two, so the boring bar is is bent by the cutting reaction force F, as shown in FIG. 2, reducing the accuracy of the boring process.

(b) Even if the bending rigidity of the boring bar can be increased, since the boring bar can move freely within the range of the gap, the processing tolerance cannot be made smaller than the size of the gap.

(c) When the preload on the rolling bearing 7 is increased, the rotational resistance of its inner ring increases, and the support bush 6 cannot be rotated due to the frictional force with the boring bar 2, causing both to slip. Therefore, it is not possible to apply much preload, and the radial rigidity of the rolling bearing is weakened, reducing bearing rotation accuracy, which further increases the machining tolerance.

(d) When the boring bar 2 is not fitted into the support bush 6, cutting oil, chips, etc. easily enter through the opening of the support bush. It is unavoidable that wear and galling occur in both of them, and this wear increases the gap and reduces machining accuracy.

The present invention aims to solve these problems all at once and improve the accuracy of drilling. Of the bearing metal,
The two split bearings are supported stationary within the bearing housing so that the boring bar is inscribed therein, and the other movable split bearings, which are expanded relative to the two split bearings by inserting the boring bar, are bored. The bar is forced to close by a pressing force that counteracts the cutting reaction force of the bar, and is installed in the bearing housing. The embolus, which is always urged to return to the extruded position where it fits into the boring bar insertion/removal port and forms an annular nozzle between it and the boring bar insertion/removal port, can be retracted in response to the cutting stroke of the boring bar. The embolus is supported by a sealed part that closes the end opening on the opposite side of the boring bar insertion/removal port of the bearing housing, and compressed air containing oil mist is supplied to the sealed part only while the boring bar is pushing the embolus into the bearing housing. A boring bar bearing device for a machine tool, characterized in that an automatic control valve is provided in the bearing housing between the split bearing pieces, and a groove is formed in the inner surface of the split bearing pieces to communicate the space before and after the split bearing pieces.

(2) Among the split bearing metal parts, each of which is divided into three parts to form a wedge-shaped oil film in cooperation with the boring bar,
The two split bearings are supported stationary in the bearing housing so that the boring bar is inscribed therein, and a bearing metal pressing device is installed that can press the other movable split bearing metal against the boring bar against the cutting reaction force thereof. installed in the bearing housing, and providing a means for opening the movable split bearing bracket on the stationary side at least when a boring bar is inserted;
In addition, the boring bar insertion/removal port of the bearing housing is enlarged so as to form an annular nozzle between the boring bar inserted therein, and the boring bar is constantly urged to return to the extrusion position where the boring bar is inserted into the boring bar insertion/removal port. The embolus, which forms an annular nozzle between the bar insertion and removal port, is supported by a sealed part that closes the opening on the opposite side of the boring bar insertion and removal port in the bearing housing so that it can retreat in response to the cutting stroke of the boring bar. an automatic control valve that supplies compressed air containing oil mist into the bearing housing between the sealing part and the split bearing ring only while the embolus is pushed into the bearing housing by the bar; The invention is characterized in that an automatic control device is provided for causing the bearing presser to press the movable split bearing only during the cutting stroke, and a groove is provided in the inner surface of the split bearing that communicates the space before and after the split bearing. Boring bar bearing device for machine tools.

The gist is:

3 to 5 show an embodiment of the first invention, in which the bearing housing has a housing main body 11.
A front lid 12 that closes the front end of the lumen 11a, and a cylindrical spring receiver 14 that seals the rear end of the lumen through the rear lid 13 are integrally connected and fixed. An insertion/removal port 12a for the boring bar 2 is provided. In the inner cavity 11a, there is a split bearing metal 1 divided into three parts.
5, 16, and 17 are fitted in contact with the front lid 12, and the rear end of the split bearing metal is supported by the rear lid 13 via a sleeve 18.

Each split shaft bearing 15, 16, 17 has a bore 11, respectively.
It has an outer arcuate surface that is in full contact with the inner surface of the boring bar 2, and an inner arcuate surface (bearing surface) having a radius R that is larger than 1/2 of the outer diameter D of the boring bar 2. The split bearings 16 and 17 on both sides of the lower part are statically supported by the housing body 11 so that the boring bar 2 is inscribed therein, and the semicircular movable split bearings 15 can be opened and closed with respect to the split bearings 16 and 17 on the lower stationary side. It is free. The diameter d of the circle inscribed in the three split bearings 15, 16, and 17 at three points A, B, and C becomes the boring bar diameter D when the movable split bearings are opened, as shown by the solid line in FIG.
When the diameter becomes equal to or larger than , and when the gap e between the upper and lower split bearings becomes zero and the split bearings are completely closed, the chamfered portion of the tip of the boring bar inserted as shown by the chain line in the same figure. The diameter is smaller than the diameter D within the range that can be expanded by 2a.

Reference numeral 19 denotes a compression spring that presses down the top of the upper movable split bearing 15 at two locations, front and back. Each compression spring 19 is fitted into a hole bored in the housing body 11, and its upper end is inserted into the hole. are supported by adjustment screws 20 screwed into the respective parts. By adjusting the rotation of the adjusting screw 20, the pressing force of the movable split bearing 15 against the boring bar is adjusted so as to overcome the cutting reaction force of the boring bar transmitted to the bearing device. Although not shown, between the housing body 11 and its mounting base 21 or between the mounting base 21
Needless to say, a device for adjusting the stationary side split bearings 16, 17 on both sides of the lower part so that the boring bar 2 is inscribed therein is provided between the shaft and the bed of the machine tool that supports it. Reference numeral 22 indicates a key for locking the abutting ends of the split bearings 16 and 17 to the housing body 11.

23 is a disc-shaped embolus fixed to the tip of a hollow support rod 24 that slidably passes through the rear lid 13; 25 is a disk-shaped embolus held within the hollow support rod 24 between the tip and the cylindrical spring receiver 14; The compression spring 25 has a plurality of hollow support rods 24 recessed in the inner wall of the hollow support rod through hole of the rear lid 13, and a valve 26 provided in the shape of a flange at the base end of the compression spring 25 when no external force is applied. In this pushing position, the embolus 23 fits into the boring bar insertion/removal opening 12a of the front cover as shown in FIG.
An annular nozzle 27 is formed between the two. Embolism 23
The outer circumferential surface of the boring bar 2 is always located on or within the extended cylindrical surface E of the outer circumferential surface of the boring bar 2.

A pipe 28 is connected to the cylindrical spring receiver 14, and the inner chamber of the cylindrical spring receiver is connected to a compressed air supply machine containing oil mist through the pipe 28. Reference numeral 29 denotes a groove in the longitudinal direction of the boring bar that is recessed inside the abutting portions of the split bearing pieces 16 and 17, and the groove 29 constantly communicates the spaces in the bearing housing before and after the split bearing pieces.

When drilling a workpiece, use the boring bar 2.
When the embolus 23 is pushed forward into the bearing housing 11, 12, 13, 14 as in the conventional case, the rear cover 13
The valve 26 that closes the notched through hole 13a opens, and the compressed air supplied from the pipe 28 flows through the through hole 13a.
The liquid is ejected from the annular nozzle 27 through the groove 29 and the space 12b in the dish-shaped front cover 12 in sequence from a. For this purpose, the boring bar 2 inserted into the bearing housing
Cutting oil, chips, etc. adhering to the surface are blown away and cleaned by the ejected air.

Also, the embolus 23 and the Borig bar 2 are split into the bearing metal 1.
5, 16, and 17 as shown in FIG. 4, the mist of lubricating oil contained in the compressed air passing through the groove 29 spreads between the bearing surface of the split bearing metal and the boring bar. Lubricate the outer surface. Therefore, the cutting reaction force F (sixth
Figure) Split bearing bracket 15 receives a pressing force that opposes
connects the boring bar 2 through point A on its bearing surface.
is pressed against the split bearings 16 and 17 on both sides of the lower part, and the split bearings on the stationary side support the boring bar 2 at points B and C on the bearing surface, and measure the center position of the boring bar 2. A viscous wedge-shaped oil film is formed at contact points A, B, and C of each split bearing metal to support the boring bar. In other words, the gap between the boring bar and the bearing metal has a minimum oil film thickness, and even if the boring bar receives the cutting reaction force F as shown in Fig. 6, the boring bar rotates tilted within the bearing metal. Since the center position will not go awry, the boring bar 2 is completely supported by the bearings 15, 16, and 17 from the position shown by the solid line in Figure 4 or its vicinity until it reaches the position shown by the chain line in the figure. By setting the cutting stroke of the workpiece 4 so that the hole-boring process is performed on the workpiece 4, the accuracy of the hole-boring process can be significantly improved compared to the conventional method shown in FIG.

Furthermore, while the boring bar 2 is not engaged with the embolus 23, the embol blocks the boring bar insertion/removal port 12a, so there is no risk of cutting oil, chips, etc. entering through the insertion/removal port, which eliminates the drawbacks of the conventional device. It can be resolved all at once.

However, in this invention, the boring bar inserted into the bearing device slides and rolls into contact with the split bearing metal while pushing open the split bearing metal, which is always biased to close. Also, the upper split bearing metal will be slightly tilted, and the load will be concentrated on the tip of the boring bar, and the same phenomenon will occur when the boring bar comes out of the bearing device. If the closing force of the bearing ring must be increased, the bearing surface may become more susceptible to wear.

FIGS. 7 to 11 show an embodiment of the second invention that solves this drawback, and in the figures, members denoted by the same reference numerals as in FIGS. 3 and 5 are corresponding members, and are similar to each other. It has the following configuration.

The bearing extrusion device has an upper movable split bearing 15.
A single-acting cylinder 30 facing the center of the top of the housing body 11 is provided integrally with the piston 3.
The lower end rod portion 31a of the cylinder head 1 is brought into direct contact with the movable split bearing metal, and a pressure control system is installed in the pipe line between the pipe 33 connected to the cylinder lid 30a and the compressed air source 34 so as to constantly communicate with the cylinder chamber 32. A valve 35 and a solenoid switching valve 36 are inserted. Further, the means for opening the movable split bearing 15 when inserting the boring bar includes notches 15a provided on both side edges of the split bearing 15;
A leaf spring 37 is shown sandwiched between the notches 16a and 17a provided at the top of the lower split bearings 16 and 17, respectively, to open the two parts, and the leaf spring 37 is connected to the cylinder. It has elasticity that can push up the piston 31 when the chamber 32 communicates with the outside air.

The automatic control device for the electromagnetic switching valve 36 includes a dog 38 attached to the feed unit 1a that advances and retreats integrally with the boring head 1, a dog 38 attached to the bed 10 side, and a front and rear end G of the cutting stroke S of the workpiece 4 by the cutting tool 3; A limit switch 3 which is switched by the dog 38 at H and outputs a signal.
9 and 40, when the switch 39 issues a signal, the electromagnetic switching valve 36 is switched to the lower position in FIG. When the air is released, the electromagnetic switching valve 36 returns to the upper position (regular position) shown in FIG. 7 and communicates the cylinder chamber 32 with the outside air.

41 is a limit switch that detects the backward end of the feed unit and issues a stop signal;
42 is a boring bar drive motor mounted on the boring head 1.

When drilling a hole in the workpiece 4, the feed unit 1a, that is, the boring bar 2 moves forward and embolizes the embolus 23.
When the valve 26 is pushed into the bearing housing, the valve 26 opens and the compressed air supplied from the pipe 28 enters the annular nozzle 27.
The compressed air blows out cutting oil and chips adhering to the surface of the boring bar 2 and cleans it, and the mist-like lubricating oil contained in the compressed air spreads between the bearing surface of the split bearing metal and the boring bar. Lubrication is the same as in the previous embodiment.

In this way, when the tip of the boring bar 2 reaches the G position shown by the chain line in FIG. , pressure control valve 35
The compressed air adjusted to a constant pressure by the switching valve 3
6 to the cylinder chamber 32, and the piston 3
1, the upper split bearing metal 15 is pressed down with a constant pressing force P that opposes the cutting reaction force F of the boring bar. At this time, the tip of the boring bar 2 passes through the line of action of the pressing force P and reaches the G position, so there is no risk that the upper split bearing 15 will tilt with respect to the boring bar, and the boring bar is similar to the previous embodiment. Similarly, the split bearing metal 15, 1 is inserted through the wedge-shaped oil film.
It is supported by three points A, B, and C on 6 and 17.

The cutting tool 3 of the boring bar is sent by a cutting stroke S from the G position in Fig. 11 and reaches the H position.
When the drilling of the workpiece 4 is completed, the dog 38 switches the limit switch 40, and the compressed air in the cylinder chamber 32 is discharged to the outside. is opened due to the elasticity of the leaf spring 37, and the bearing load becomes approximately zero. That is, since the bearing load acts only during the cutting stroke S, there is less wear and heat generation of the bearing, and durability is improved.

The case where the movable split bearing 15 is always biased open by the plate spring 37 with respect to the lower split bearings 16 and 17 on the stationary side has been described.
Since the force required to push up the piston 31 in the normal position 6 is relatively small, the movable split bearing can be moved to the stationary side by the chamfered portion 2a at the tip of the boring bar inserted into the bearing as in the previous embodiment. It may be expanded to the lower split bearing metal.

[Brief explanation of drawings]

Figure 1 is a side view of a machine tool equipped with a conventional bearing device, Figure 2 is an explanatory diagram of its functions, Figures 3 and 4.
The figures are longitudinal sectional side views of an embodiment of the present invention in non-operation and operation, respectively, FIG. 5 is a sectional view taken along line XX in FIG. 4, FIG. FIG. 8 is a vertical cross-sectional side view of another embodiment of the present invention in FIG.
The figure is a vertical sectional front view of the bearing during operation, Figures 9 and 10 are front and side views of the bearing metal, respectively, and Figure 1
FIG. 1 is a side view of a machine tool equipped with the bearing device of FIG. 7. 1... Boring head, 2... Boring bar, 3... Cutting tool, 4... Work, 11, 12, 1
3, 14... Bearing housing, 15... Movable split bearing bracket, 16, 17... Lower split bearing bracket on stationary side, 19... Compression spring, 23... Embolus, 24...
Embolism support rod, 25... Compression spring, 26... Valve, 2
7... Annular nozzle, 28... Compressed air supply pipe containing oil mist, 29... Groove, 30... Single acting cylinder, 31... Piston, 34... Compressed air source, 36... Solenoid switching valve , 38...Dog, 39,
40...Limit switch.

Claims (1)

[Claims] 1. Of the split bearing metal parts divided into three parts so as to cooperate with the boring bar to form a wedge-shaped oil film, two parts
Two split bearings are supported stationary within the bearing housing so that the boring bar is inscribed therein. The boring bar insertion/removal opening of the bearing housing is enlarged so as to form an annular nozzle between the boring bar inserted therein and the boring bar inserted into the bearing housing. , so that the embolus, which is always urged to return to the extruded position where it fits into the boring bar insertion/removal port and forms an annular nozzle between it and the boring bar insertion/removal port, can be retracted in response to the cutting stroke of the boring bar; The bearing is supported by a sealed part that closes the end opening on the opposite side of the boring bar insertion/removal port of the bearing housing, and only while the boring bar is pushing the embolus into the bearing housing, compressed air containing oil mist is split between the sealed part and the bearing housing. A boring bar bearing device for a machine tool, characterized in that an automatic control valve is provided in the bearing housing between the metal parts, and a groove is formed in the inner surface of the split bearing metal to communicate the space before and after the split bearing metal. 2. The boring bar bearing device for a machine tool according to claim 1, wherein the outer circumferential surface of the embolus is always located on or within the extended cylindrical surface of the outer circumferential surface of the boring bar. 3 Two of the split bearing metal parts are divided into three parts to form a wedge-shaped oil film in cooperation with the boring bar.
A split bearing is fixedly supported in the bearing housing so that the boring bar is inscribed therein, and a bearing pushing device is attached to the bearing that can press another movable split bearing against the boring bar against the cutting reaction force of the other movable split bearing. A boring bar installed in the housing, provided with a means for opening the movable split bearing bracket on the stationary side at least when inserting the boring bar, and inserting the boring bar insertion/removal opening of the bearing housing into the boring bar. The embolus is enlarged so as to form an annular nozzle between the boring bar and the embolus, which is always urged to return to the extruded position where it fits into the boring bar insertion/extraction opening and forms an annular nozzle between the boring bar insertion/extraction opening. It is supported by a sealed part that closes the opening on the opposite side of the boring bar insertion/removal port of the bearing housing so that it can retreat in response to the cutting stroke of the bearing housing.
an automatic control valve that supplies compressed air containing oil mist into the bearing housing between the sealing part and the split bearing ring only while the embolus is being pushed into the bearing housing by the boring bar; An automatic control device is provided to cause the bearing presser to press the movable split bearing only during the cutting stroke, and a groove is provided in the inner surface of the split bearing that communicates the space before and after the split bearing. Boring bar bearing device for machine tools. 4. The boring bar bearing device for a machine tool according to claim 3, wherein the outer circumferential surface of the embolus is always located on or within the extended cylindrical surface of the outer circumferential surface of the boring bar.