JPH0121682Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention mainly relates to a lathe for turning crankshaft pins and journals.

Conventionally, crankshafts used in internal combustion engines, etc., were cut from the black crust to the finished diameter using a single cutting tool. For this reason, if there are cast burrs on the black skin part,
There was a problem in which pitting occurred and uncut parts were left on the finished diameter according to the pitching.

This invention was made with the aim of improving this problem, and was designed to create a lathe that is equipped with a rough cutting tool and a finishing tool, and can perform continuous operations from rough cutting to finishing by changing the feed speed of these tools. This makes it possible to perform highly accurate finishing even when there are cast burrs on the black skin.

This invention will be explained in detail below with reference to an embodiment shown in the drawings. In the figure, 1 is a bed;
At the top, spindle heads 3 are installed at each processing station so as to sandwich the conveying line A in an alternating manner.

Each spindle head 3 is provided with a spindle 3a that is rotated by a spindle motor 4 via a power transmission means 5, and a tailstock 12 is provided in front of these spindles 3a. Both ends of the workpiece 6 are held between a center 12a provided on the stand 12 and a chuck 7 provided at the tip of the spindle 3a. In addition, a gate-shaped column 2 is installed in each processing station so as to straddle the conveyance line A, and these columns 2 are movable in a direction perpendicular to the conveyance direction by means of a feeding means (not shown) such as a cylinder. A slide 8a is provided. A feeding means 1 such as a cylinder is provided on the front surface of the slide 8a.
An upper tool rest 10a which is vertically movable is provided by 1b, and a tool 9 for turning the front portion 6a of the workpiece 6 is attached to this upper tool rest 10a.

Furthermore, slides 8b and 8c are installed at opposing positions across the workpiece 6 held between the spindle 3a and the center 12a of the tailstock 12, and slides 8b and 8c are provided with slides 8b and 8c that move the workpiece 6 forward and backward in the direction of approach and separation. Left and right tool rests 10b and 10c are provided which can be freely moved. These tool rests 10b and 10c are provided with nut members 20 as shown in FIG. 3, and each nut member 20 has a screw shaft 21 rotatably supported on the slide 8b side via a bearing member 25. are screwed together. These ball screw shafts are reverse screws with different leads, and are synchronously rotated via a gear train 23 by a synchronous shaft 22 rotated by a feeding means 11c. One turret 10b is advanced by 0.048 mm, and the other turret 10c is advanced by 0.05 mm, for example, toward the workpiece 6 in response to the rotation. The tool rest 10b has a tool ₉₁ having finishing tips 9a, 9b at its tip, and the tool rest 10c has a rough machining tip 9c, at its tip.
A tool ₉₂ having a diameter of 9d is attached and processes the workpiece 6 as follows.

Next, to explain the operation, the workpiece 6 to be machined is carried in from the direction of arrow A in FIG. and is held by the tailstock 12. When the spindle 3 starts rotating the workpiece 6 in this state, the feeder 11c simultaneously moves each tool rest 1
The ball screw shaft 21 screwed into the nut members 20 of 0b and 10c is rotated, and the tool rest 10b is moved to the fifth position.
The tool post 10c starts moving toward the workpiece 6 from point A' in the figure and from point B', which is further advanced from point A'. Since each ball screw shaft 21 has a lead difference in advance, the finished chips 9a, 9b
The turret 10b to which the tool 9 ₁ having the tool 9 ₁ is mounted is aligned along the straight line A in FIG. Move along straight line B in Figure 5.

That is, first, the tip of the rough machining tool ₉₂ attached to the tool post 10c reaches point a, contacts the black skin of the workpiece 6, and begins cutting it. After that, the rough machining tool 9 ₂ completes cutting of the black scale before reaching point b, and then the finishing tool 9 ₁ comes into contact with the workpiece 6 and starts finishing machining, as shown in Fig. 6. ,c
From the center of the workpiece 6 to each chip 9a, 9b, 9
The distances to c and 9d become equal. After that, until the finishing diameter is reached, the finishing tool 9 ₂ takes the lead, and each tool 9 ₁ and 9 ₂ simultaneously machine the workpiece 6, and the machining is completed at point d, in the range from point b to point d. Since each of the tools 9 ₁ and 9 ₂ cuts the workpiece 6 at the same time, balanced cutting is possible, and since the feed rate gradually decreases from point c to point d, highly accurate finishing is possible. Also d
By applying a dwell motion at the point, the finished diameter can be determined by the tool ₉₁ .

As detailed above, this idea involves installing a rough machining tool and a finishing tool on the tool rests facing each other, and changing the feed speed of these tools to continuously cut the black part of the workpiece. Since finishing machining can be performed, even if uncut parts are left uncut due to cast burrs on the black scale, the finishing tool will perform the finishing machining, making it possible to perform highly accurate machining.
Since the finishing tool does not come into direct contact with the black scale, tool wear is reduced and tool life can be improved.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention, and Fig. 1 is an overall plan view, Fig. 2 is a front view of the same, Fig. 3 is an enlarged sectional view of the vicinity of the tool rest, Fig. 4 is a plan view of the same, and Fig. 4 is a plan view of the same. 5 and 6 are action explanatory diagrams. 3 is a spindle head, 6 is a workpiece, 9 ₁ is a finishing tool, 9 ₂ is a rough machining tool, 10b, 10
c is the turret.

Claims (1)

[Scope of utility model registration request] A spindle head 3 and a tailstock 1 are provided to face each other across the conveyance line A of the workpiece 6 and rotate while supporting both ends of the workpiece 6 to be processed.
A finishing tool 9 1 and a rough machining tool 9 2 are respectively attached to the tool 9 ₁ and the tool 9 ₂ for rough machining. Multiple turrets 1 set so that the side with ₂ installed takes the lead
0b, 10c and the nut member 20 provided on each of the above-mentioned tool rests 10b, 10c are each threaded with a reverse thread, and the feed amount on the side of the tool rest 10b to which the finishing tool ₉₁ is attached is A lathe comprising ball screw shafts 21 with a lead difference set in advance to increase the lead difference, and a drive means for rotating these ball screw shafts 21 synchronously.