US3296901A - Machine tools - Google Patents

Description

967 KIYOSHI SAWADA 2 MACHINE TOOLS Filed May 15, 1964 3 Sheets-Sheet l IN ENTOR.

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Jan. 10, 1967 Filed May 13, 1964 KEYOSHI $AWADA MACHINE TOOLS 3 Sheets-5heet 3 INVENTOR.

United States Patent 3,296,901 MACHINE TOOLS Kiyoshi Sawada, Numazu-shi, Japan, assignor to Toshiba Machine Co., Ltd., Tokyo, Japan Filed May 13, 1964, Ser. No. 367,164 Claims priority, application Japan, May 14 ,1963, 38/ 24,042 Claims. (Cl. 82--2) This invention relates to machine tools such as a vertical lathe and the like including a transversal girder adapted to support a movable tool and the like.

In a conventional vertical lathe, where a work mounted on a turn table is cut the flatness of the upper surface of the work is mainly determined by the degree of horizontality of a line along which a tool post travels on the transversal girder. In a vertical lathe of large size, as the length of the transversal girder carrying the tool post increases the amount of bending of the girder as the tool post travels along it will be increased owing to the weight of the transversal girder itself as well as the weight of the tool post. As a result it will become difficult to accurately cut the work having a horizontal plane. In order to obviate this difficulty the opposite supporting ends of the transversal girder have been cut off so as to increase the height of the middle portion thereof whereby to decrease the amount of lowering due to bending. With this construction, however, it has been difficult not only to perfectly compensate for the effect of such bending but also to easily vary the degree of compensation to bending, to fit the mean temperature of the place where the machine is operated, when the machine is put on the base, and also to vary repeatedly the degree of compensation to bending to be caused due to aging of the material. Especially, in vertical lathes as it is not permissive to make too high the height of the middle portion there was a danger of over compensation.

It is the object of this invention to obviate the difficulty mentioned above.

Further object of this invention is to provide an improved machine tool such as a vertical lathe wherein bending of the transversal girder thereof can be compensated by simple means.

According to this invention, in a machine tool having a transversal or horizontal girder, a beam is provided along the girder and one or more means are interposed between a beam and the transversal girder to vary the degree of compensation to bending, said transversal girder being in parallel with said beam.

The features of the invention which are believed to be novel are setforth with particularity in the appended claims. The invention itself, however, as to its organization together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 shows a front elevation of a vertical lathe embodying this invention;

FIG. 2 shows a side view of the lathe shown in FIG. 1;

FIG. 3 is a graph showing comparison between the amounts of bending of transversal girder of the prior art and that of this invention;

FIG. 4 shows a front elevation of a modification of this invention;

FIG. 5 is a graph showing the comparison between the amount of bending of the transversal girder of the modified lathe shown in FIG. 4 and that of the prior art;

FIG. 6 shows a cross-sectional view of the transversal girder of another modification of this invention; and

FIGURE 7 shows a perspective view of the connecting means.

Patented Jan. 10, 1967 "ice Referring now to FIGS. 1 and 2 of the accompanying drawings, there is shown a vertical lathe comprising a pair of spaced apart columns 2 and 3 secured on a base 1, a transversal or horizontal girder 4 with its opposite ends supported by the columns and tool posts 7 which are guided to move along the transversal girder 4 and carry holders 6 for cutting tools 5 at their lower ends. As in the conventional lathe the tool posts 7 are fed by a lead screw 8. In a recess of the base 1 between the columns 2 and 3 is mounted a turn table 10 adapted to support a work 11 to be turned.

In accordance with this invention a beam 12 is provided above and along the transversal girder 4 which is in parallel thereto. The girder and the beam are interconnected by suitable connecting means such as pedestals 17, 18 and 19 having the same heights and replacable spacers or shims 14, 15 and 16. At the central portion of the span length between said columns 2 and 3, the shim 16 is made thinner than the others i.e., shims 14 and 15 at the opposite ends, said shim 16 being removably attached to the upper surface of the pedestal 19 by means of setting bolts (not shown), which respectively rigidly fix the beam 12 through each of holes 36 and 37 of the pedestal 1-9 and the shim 16,-and the other setting bolts rigidly fix the girder 4 through holes 35 of the pedestal 19.

According to this invention constructed as above described as the central portion of the transversal girder 4 is connected to the beam 12 by a connecting means having shorter length than those located at the opposite ends the central portion of the girder will be pulled upwardly. As a result even when the central portion is bent downwardly due to the weight of the tool posts 7 and or the weight of the girder itself, it is able to maintain the path of the tool posts 7 and or the weight of the girder itself, it is able to maintain the path of the tool posts substantially horizontal.

The amount of bending of the transversal girder is shown in FIG. 3 wherein the abscissa indicates the distance along the girder and the ordinate indicates the amount of bending. In FIG. 3 curve A represents the amount of bending of the prior girder which is merely mounted upon the columns 2 and 3, curve B that of the prior girder which is securely supported by columns 2 and 3, and curve C represents the amount of bending of the girder embodying this invention. As can be clearly understood from these curves the amount of bending of the girder embodying this invention is far smaller than those of the prior art.

FIG. 4 shows a modified embodiment of this invention wherein a transversal girder 4 carrying tool posts 7 is supported by a pair of spaced columns 2 and 3 mounted upon a turn table 10' and a hollow or annular work 11 is supported outside of the turn table 10.

Again, a beam 12 is disposed above and along the transversal girder 4 and these members are connected together by connecting means 23, 24 and 25 including replaceable shims 20-, 21 and 22, assembled with the corresponding pedestals, it being understood that the thickness of the central shim 22 is made smaller than that of the outer shims 20 and 21 to provide a similar function as described above. Further a screw means 26 is vertically arranged between the under surface of the beam and the upper surface of the girder. Said screw means 26 has a bolt rigidly mounted on the upper surface of the girder and a nut. When the nut is threaded on the bolt to be pushed toward the under surface of the beam, compression stress occurs in the vertical direction between the beam and the girder to vary the degree of compensation to bending.

FIG. 5 shows the amount of bending of the horizontal girder of the lathe shown in FIG. 5 wherein the abscissa indicates the distance along the girder and the ordinate the amount of bending. Curve C represents the amount of bending of the girder embodying this invention as compared to that of the prior art indicated by the curve D which shows that the amount of bending is greatly reduced by the novel connecting means of this invention.

While in the embodiments illustrated in FIG. 1, 2 and 4 the beam 12 is located above the horizontal girder 4, it will be understood that this invention is by no means limited to this particular arrangement.

For example as shown in FIGURE 6, the transverse girder 30 may be formed so as to have a rectangular hollow cross section to house a beam 31. A connecting means 32 such as a screw is provided at the center of the girder span, said girder being supported at its opposite ends on columns (not shown). By the adjustment of the screw, the degree of compensation to vertical bending may be varied. Other setting screws 33 and 34 shown in FIG- URE 6 are provided at opposite sides of the girder at suitable positions in its longitudinal direction.

The operation of this modification is similar to that of the other embodiment.

As can be clearly noted from the foregoing description bending and lowering of the transversal girder can be effectively compensated or prevented by connecting a transversal girder to a horizontal beam through one or more adjustable connecting means whereby to move a tool and the like along a substantially horizontally plane. Moreover even when the compensation is effected by mean temperature variation due to seasonal circumstances or aging of the material, it can be easily and accurately corrected.

Although specific embodiments have been disclosed to illustrate the invention; it will be evident that the teachings apply to other kinds of machine tools and that many modifications and variations fall within the scope of this invention. It therefore is to be intended that within the scope of the appended'claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A machine tool comprising a horizontal girder supported at its opposite ends, on columns spaced-apart, a beam extending along said girder and connecting means interconnecting said beam and said girder, a plurality of said connecting means being made thinner than the remaining connecting means and made variable in height to vary the degree of the compensation for the bending of said girder.

2. A machine tool according to claim 1 in which said horizontal girder includes a part which extends with a part of said beam from one of its positions supported by said columns.

3. A machine tool according to claim 1 in which each of said connecting means comprises a shim connected with a pedestal with setting bolts.

4. A machine tool according to claim 2 in which each of said connecting means comprises a shim connected with a pedestal with setting bolts.

5. A machine tool according to claim 2 in which said connecting means consists of a bolt and a nut.

References Cited by the Examiner UNITED STATES PATENTS 2,912,905 11/1959 Berthiez 90-16 FOREIGN PATENTS 1,315,481 12/1962 France.

938,947 10/1963 Great Britain.

WILLIAM W. DYER, JR., Primary Examiner.

LEONIDAS VLACHOS, Examiner.

Claims (1)

1. A MACHINE TOOL COMPRISING A HORIZONTAL GIRDER SUPPORTED AT ITS OPPOSITE ENDS, ON COLUMNS SPACED-APART, A BEAM EXTENDING ALONG SAID GIRDER AND CONNECTING MEANS INTERCONNECTING SAID BEAM AND SAID GIRDER, A PLURALITY OF SAID CONNECTING MEANS BEING MADE THINNER THAN THE REMAINING CONNECTING MEANS AND MADE VARIABLE IN HEIGHT TO VARY THE DEGREE OF THE COMPENSATION FOR THE BENDING OF SAID GIRDER.

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