JPH0295541A - Machine tool for exclusive use - Google Patents

Abstract

PURPOSE:To increase the working accuracy of a work by a forming the part reaching the same height as the distance from the bottom face of the work at least from each bottom part of a head stock and guide plate to the working hole axial line by the material equal to the respective work at thermal expan sion coefficient, and providing a coolant passage on a bed, head stock guide plate inner parts. CONSTITUTION:By circulating a coolant to the passages 2a, 6a, 25a provided at the internal parts of a bed 2, head stock 6 and guide plate 25 as well as performing working with oiling a work W by a cutting oil, the work and device are cooled and the deformation by heat is constrained. Also, the part reaching the height in the same distance as that from the bottom face of a work to the working hole axial line at least from the bottom parts of the head stock 6 and guide plate 25 is formed by the material whose thermal expansion coeffi cient is equal to that of the work. Thus the head stock and guide plate(bush base) are made in the same environment as the works for heat, it is evaded to cause the difference in the thermal displacement in the upper and lower directions which becomes the cause of decentering among the work, heae stock and guide plate and the working accuracy can be improved.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) The present invention relates to a special machine tool for machining, for example, a cylinder block of an automobile engine, and more specifically, to a special machine tool with improved functions to cope with thermal effects. (Prior Art) A general dedicated machine tool is a boring machine. This dedicated boring machine is equipped with a saddle that slidably holds the spindle head at one end of the bed, and a fixture for clamping the workpiece at the other end of the bed, that is, at the workpiece machining position. We are prepared. Further, a bushing stand is provided on the side of the fixture to support a bushing for centering and guiding the tool attached to the spindle head. In such a dedicated boring machine, the cutting part of the workpiece and various parts of the equipment such as the motor and bearings generate heat during operation.
Since the deformation caused by thermal expansion can cause misalignment when a tool is inserted into a workpiece during machining, which may affect machining accuracy, various heat countermeasures have been considered. Conventionally, in addition to pouring cooling liquid onto the workpiece, there are also systems that circulate cooling liquid through channels formed inside the headstock or bed to suppress the rise in temperature of the bed. there were. Note that a technique for providing a cooling liquid flow path inside a bed or the like is disclosed in, for example, Japanese Utility Model Application Publication No. 59-66534. (Problem to be solved by the invention) However, in the case of a dedicated boring machine such as the one described above, thermal deformation can be greatly suppressed by using a cooling liquid, but it is still not possible to completely eliminate the effects of heat. It was extremely difficult to get rid of it. Furthermore, the workpiece and processing machine are
For example, since they are made of different materials such as aluminum and iron, they naturally have different coefficients of thermal expansion, and this results in different degrees of thermal deformation. This causes the axis of the machined hole in the workpiece and the axis of the corresponding tool to shift vertically, causing the hole to be machined in the workpiece. There have been problems in that it becomes difficult to insert the tool into the tool, and even if the tool can be inserted, machining defects may occur, such as machining in a misaligned state. In particular, when machining a hole in a crankshaft using a tool holding bar for line poling with multiple tools attached in the axial direction, the temperature of the workpiece increases as the cutting area increases, and the temperature of the workpiece, processing machine, and bushing table increases. The vertical deviation between the machining axes becomes larger, leading to problems such as misalignment and bending of the axes during machining, which affects machining accuracy. Therefore, it has been a challenge to solve these problems. (Purpose of the Invention) This invention was made with attention to such conventional problems, and it deals with the thermal deformation that occurs between the workpiece, the processing machine, and the bush table (guide plate), and improves the processing accuracy. The aim is to provide specialized machine tools that can be further improved.

[Structure of the invention]

(Means for solving the problem) The dedicated machine tool according to this invention is placed on a bed. A saddle capable of advancing and retracting toward the workpiece machining position is provided, and a rotary drive unit is provided on the saddle that is connected to a headstock for holding a spindle and the spin lower lever via a universal joint, and the rotary drive unit is connected to the workpiece machining position is provided with a fixture for clamping the workpiece, and on the same base as the fixture, is provided with a guide plate having a bushing for inserting and centering a tool or a tool holding bar whose base end is connected to the spindle, A portion from the bottom of the headstock and the guide plate to at least the same height as the distance from the bottom of the workpiece to the axis of the machined hole is formed of a material having the same coefficient of thermal expansion as the workpiece, and By providing a cooling liquid flow path inside the guide plate, this configuration is used as a means for solving the conventional problems. (Function of the Invention) The dedicated machine tool according to the present invention performs machining while applying cutting oil to the workpiece as a very simple means of fishing, and also injects cooling liquid into the channels provided inside the bed, headstock, and guide plate. By circulating it, the workpiece and equipment are cooled and deformation due to heat is suppressed. Further, by forming a portion from the bottom of the headstock and the guide plate to a height that is at least the same distance as the distance from the bottom of the workpiece to the axis of the machined hole, the headstock and the guide plate are formed of a material having the same coefficient of thermal expansion as the workpiece. The bushing head is placed in the same thermal environment as the workpiece, so that there is no difference in the amount of thermal displacement in the vertical direction between the workpiece, the headstock and the guide plate, which causes misalignment. moreover,
By connecting the spindle held by the headstock and the rotary drive unit with a universal joint, displacement caused by thermal effects between the headstock and the rotary drive unit and vibrations from the rotary drive unit side can be suppressed. The joint absorbs it and maintains the straightness and rotational state of the spindle and tool or tool holding bar. (Example) Hereinafter, an example of the present invention will be described based on the drawings. That is, the dedicated machine tool 1 performs line polling on the crankshaft hole of a workpiece W, which is an engine cylinder block made of aluminum alloy, for example.As shown in FIG. A headstock that is provided with a fixture 3 that positions and holds the workpiece W on a workpiece conveyance path by a transfer device or the like, and a saddle 4 that can move forward and backward with respect to the fixture 3, and that holds a spindle 5 on the saddle 4. 6 and the spindle 5
The rotary drive unit 8 is connected to the rotary drive unit 8 via a universal joint 7. As shown in FIG. 2, the bed 2 has a circumference of 2
It has a layered structure, and a cooling liquid flow path 2a is continuously formed in the space, forming the entire surface of the bed, and cooling the entire surface of the bed by splashing it. Coolant is supplied from a supply pipe 29. The flow path 2a has an open top surface in order to obtain a sufficient cooling effect, and the cooling liquid overflowing from the flow path 2a cools the top surface of the bed. It was leaked, and the overflowing amount was also leaked to 30. The liquid is then collected from the gutter 30 into the drop guiding section 35 and discharged into the cooling liquid circulation path 36 below. The saddle 4 is guided horizontally by a base 9 fixed to the upper surface of the bed 2, and is connected to a feed motor 10 provided at the end of the base 9 via a power transmission mechanism such as a pole screw, and The forward and backward movement is performed by forward and reverse rotation of the motor 10. The entire main body of the headstock 6 is made of a material having the same coefficient of thermal expansion as the workpiece W, and it holds the spindle 5 horizontally and rotatably through the spindle rad 11, and also holds the spindle 5 in its upper and lower positions. , a small spindle 13.13 is held parallel to said spindle 5 via a spindle head 12.12. Further, inside the headstock 6, there is formed a cooling fluid flow path 6a that continues along the outer diameter of the bearing of each spindle 5, 13, 13. A cooling liquid is supplied to this flow path 6a by a supply pipe 31, and is discharged onto the bed 2 below from an upper discharge port 32. Coaxially connected to the spindle 5 is a tool holding bar 15 for line poling, in which a plurality of cutting tools 14 are attached in the same phase at predetermined intervals in the axial direction. , a tool 16.16 for machining another hole (for example, a dowel hole) in the workpiece W is connected. The rotary drive section 8 is composed of a gear box 17 containing a suitable gear mechanism and a drive motor 18,
A corresponding output shaft 19.degree. 20.20 is provided on the coaxial line of each of the spindles 5, 13.13. In this embodiment, the universal joint 7 is a flanged cylindrical member 7.
Connecting members 7b, 7 with flanges are attached to both ends of a by bolts via elastic members such as leaf springs or rubber bushings.
This is a flange-type flexible shaft joint formed by connecting the spindle 5 and the corresponding output shaft 19. A similar universal joint 21.21 is also provided between the small spindle 13.13 and the corresponding output shaft 20.20.
is an intermediary. The rotation of said drive motor 18 is thereby transmitted to the respective spindle 5.degree. 13 via the gear mechanism, the respective output shaft 19.20 and the respective universal joint 7.21. The fixture 3 includes a locate pin 23 and a frame 3b on a base 3a, and a clamper 22 for suppressing a workpiece and a bar 15 placed on the frame 3b when inserting or removing the bar 15 from the workpiece W. It is equipped with a known lift device for lifting the workpiece W to a position where it does not interfere with the circumferential surface, cutting oil supply piping, etc. (not shown). Further, on the base 3a, with the workpiece machining position in between, a bushing plate 24 as a guide plate for the tool is provided on the headstock 6 side, and a bushing plate 25 as a guide plate for the bar 15 is provided on the opposite side. There is. The entire bushing plate 24 except the bushing 26 is made of a material having the same coefficient of thermal expansion as the workpiece W, and has an opening 24a into which the rod 11 is loosely fitted into the spindle when the saddle 4 is in the forward position, and an opening 24a in the middle. A bushing 26.26 is provided for centering and guiding the boring tool 16.16 therethrough. The bushing plate 24 has its lower end fixed to a support member 27 made of the same material provided on the base 3a, and both sides are slidable in the vertical direction by guides (not shown) provided on the frame 3b. It is held in such a way that thermal deformation in the vertical direction can be tolerated. The main body of the bushing stand 25 is made of a material having the same coefficient of thermal expansion as the workpiece W, and a rotary bushing 28 for positioning and holding the tip of the bar 15 is attached near the upper end. A coolant flow path 25a is formed inside. Cooling liquid is supplied to this flow path 25a through a supply pipe 33, and is discharged from an upper discharge port 34 to the gutter 30 below. Incidentally, around the bushing 26 of the bushing plate 24 and at the upper end of the bushing base 25, nozzles and channels for discharging cutting oil are arranged to further enhance the cooling effect. In this frame 3b, the cooling liquid applied to the workpiece W, bushings 26, 28, etc., along with chips, flows downward through the base 3a and the fall guide plate 37, 38 in the bed 2, as shown in FIG. The coolant is discharged to the coolant circulation path 36 of the coolant. In the dedicated machine tool 1 having the above-described configuration, when the workpiece W is transported to a processing position by a transfer device (not shown) and clamped by the fixture 3, the saddle 4 is advanced by rapid traverse by the feed motor 10. As shown by the imaginary lines in the figure, the bar 15 is passed through the opening 24a of the bushing plate 24 and penetrated into the machined hole of the workpiece W, and the tools 16.16 are inserted into the bushings 26.26 of the bushing plate 24, respectively. At the same time, the tip of the bar 15 is fitted into the rotary bushing 28 of the bushing base 25. Then, after lowering the workpiece W to a predetermined processing position by a lift device (not shown), the workpiece W is firmly held by the clamp 22, and then the drive motor 18 is used to move the bar 15 and the tool along with each spindle 5, 13. 16.
16, and at the same time the feed motor 10 rotates the saddle 4.
By cutting and feeding. Drill a hole in the workpiece W. During this time, cutting oil continues to be supplied to the workpiece W, the bushing plate 24, and the bushing stand 25, and the bed 2,
Each flow path 2a, 6a, 2 of the headstock 6 and bushing base 25
A cooling liquid is circulated within 5a with a supply source outside the apparatus, thereby cooling the workpiece W and the processing machine itself to suppress deformation due to heat. Furthermore, the dedicated machine tool 1 is
Headstock 6, bushing plate 24, and bushing base 25
For example, the bar 15 is made of the same aluminum alloy as the workpiece W, and has the same coefficient of thermal expansion as the workpiece W, and the structural part holding the bar 15 and the workpiece W are in the same thermal environment during machining. ing. Therefore, even if heat affects both, there is no need to worry about a large difference in vertical displacement between them because the degree of thermal deformation is the same, and the bar 15 is always aligned with the workpiece W. It can be inserted in this state, and it is also held in an unbent state by the bushing base 25, allowing accurate processing. moreover,
If thermal deformation occurs in the headstock 6, a displacement will occur between the headstock 6 and the rotation drive unit 8, which has a different degree of thermal expansion, but the output shaft 19, 20 and each spindle 5, 13 will be displaced. The universal joint 7.21 interposed between the spindles 5.21 absorbs any thermal deviation between the two or vibrations from the rotational drive unit 8 side, and maintains the normal posture and rotation of each spindle 5.13. , there are no problems with machining. In this embodiment, the main spindle stock 6, bushing plate 24, and bushing base 25 are all made of a material with the same coefficient of thermal expansion as the workpiece W. With respect to the thermal displacement in the vertical direction of the workpiece W that occurs between the bottom surface and the axis of the machined hole, the side that holds the tool 15, 16, that is, the headstock 6, the bushing plate 24, and the bushing base 25, move away from the bottom at the same rate. Since it is sufficient to follow the thermal expansion with the same displacement up to the tool axis, as shown in FIG. Distance H from the bottom to the machined hole axis
The same effect can be obtained even if the part reaching the height of the distance equal to [the filled-in part in Fig. 3] is made of a material with the same coefficient of thermal expansion of the workpiece.

【Effect of the invention】

As explained above, this invention not only suppresses thermal deformation caused by the cooling fluid of the entire device, but also creates the same thermal environment for the workpiece side and the headstock and guide plate on the side that holds the tool. Therefore, the difference in vertical displacement between the two due to thermal expansion can be eliminated as much as possible, the misalignment between the tool and the machined hole can be eliminated, and the machining axes of the tool and bar can be prevented from bending, thereby improving the tool posture. It has the excellent effect of being able to maintain straightness and significantly improving processing accuracy.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a partial cross-section of a dedicated machine tool according to an embodiment of the present invention, and FIG.
-A field of view sectional view, ff53 is a diagram for explaining the material composition of the headstock and guide plate for the workpiece. W... Workpiece, 1... Special machine tool, 2... Bed, 3... Fixture, 4... Saddle, 5... Spindle, 6... Headstock, 7... Universal joint, 8... Rotation drive unit, 15... Tool holding bar 16... Tool, 24... Bushing plate (guide plate), 25... Bushing stand (guiding plate), 2a, 6a , 25a... flow path.

Claims (1)

[Claims] (1) A bed is provided with a saddle that can move forward and backward toward a workpiece processing position, and on the saddle, a headstock that holds a spindle and a rotation drive unit that is connected to the spindle via a universal joint are provided, At the workpiece processing position,
A guide plate is provided on the same base as the fixture for clamping the workpiece, and a guide plate is provided with a bush for inserting and centering a tool or a tool holding bar whose base end is connected to the spindle. A portion extending from the bottom of the table and the guide plate to a height at least the same distance as the distance from the bottom of the workpiece to the axis of the machined hole is formed of a material having the same coefficient of thermal expansion as the workpiece, and the bed, headstock and A special machine tool characterized by a cooling fluid flow path provided inside the guide plate.