Lathe

A lathe (1) with a simple construction that is capable of making the relative displacement of a headstock (2) and tool rest (3) due to thermal deformation smaller.The lathe (1) comprises: a head including a headstock attaching section (51), and a slide attaching section (52) which has a portion with a height lower than the headstock attaching section; a headstock (2) attached to the headstock attaching section (51); a slide section (6) attached to the slide attaching section (52); and a tool rest (2) provided laterally to the headstock (3) and attached to the slide section (6).The headstock (2) is attached to the headstock attaching section (51) slanted to the tool rest side with respect to the direction in which the headstock (2) and the tool rest (3) are lined up.

TECHNICAL FIELD

The present invention relates to a lathe for performing specific machining on work.

BACKGROUND ART

A lathe has heat sources such as a spindle motor and spindle. This means thermal deformation occurs to a lathe during work machining. Comparing the headstock and the tool rest, the direction of the thermal deformation is very different. Therefore, when thermal deformation of a lathe occurs, the relative displacement between the headstock and tool rest is large. In other words, the positional deviation between the work attached to the headstock and the blade tip of the tool attached to the tool rest is large. It follows that the machining accuracy of the work deteriorates.

For this point, a slanted type lathe which restricts the direction of thermal deformation of a bed is disclosed in patent literature 1. The slanted type lathe disclosed in the above patent literature is provided with a joint. The joint restricts thermal deformation of the bed in a left-right direction. Also, the joint allows thermal deformation of the bed in a lengthwise direction. The headstock and the tool rest are arranged in a line in a lengthwise direction. Therefore, compared to a case in which a joint is not provided, the relative displacement of the headstock and tool rest due to thermal deformation can be made smaller.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Utility Model Application Publication No. 1995-20201

SUMMARY OF INVENTION

Technical Problem

However, with the slanted type lathe of the patent literature, it is necessary to separate the upper surface section and rear surface section of the bed. Also, it is necessary to arrange a joint engaging section on the top section of the upper surface section. Also, it is necessary to arrange a joint rail section on the front surface of the rear surface section. Therefore, the construction is complex. Thus, an object of the present invention is to provide a lathe with a simple construction that is capable of making the relative displacement of a headstock and tool rest due to thermal deformation smaller.

Solution to Problem

(1) To solve the above problems, the present invention is a lathe comprising: a bed that has a headstock attaching section, and a slide attaching section which has a portion with a height lower than the headstock attaching section; a headstock attached to the headstock attaching section; a slide section attached to the slide attaching section; and a tool rest provided laterally to the headstock and attached to the slide section; wherein the headstock is attached to the headstock attaching section slanted to the tool rest side with respect to the direction in which the headstock and the tool rest are lined up.

According to the present invention of a lathe, a headstock is attached slanted to the tool rest side with respect to the direction in which the headstock and tool rest are lined up (the direction in which the blade tip of the tool contacts the work during work machining). Therefore, the relative displacement of the headstock and tool rest due to thermal deformation can be made smaller.

Also, according to the present invention of a lathe, it is not necessary to arrange a joint on the bed. In other words, it is not necessary to arrange a mechanism for achieving anisotropy in the direction of the thermal deformation on the bed. Therefore, the construction is simple.

(2) It is preferable for the configuration from (1) above for the headstock to have a spindle, for the tool rest to have a turret, and for the rotation center line of the spindle and the rotation center line of the turret to be arranged parallel to each other. According to this configuration, the width (the dimension in the direction in which the headstock and tool rest are lined up) of the lathe can be made small.

(3) It is preferable for the configuration from (2) above for the rotation center line of the spindle and the rotation center line of the turret to be arranged at the same height. According to this configuration, the turret can be slid in a horizontal direction while maintaining a parallel state between the respective rotation center lines.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a lathe with a simple construction that is capable of making the relative displacement of a headstock and tool rest due to thermal deformation smaller.

REFERENCE SIGNS LIST

DESCRIPTION OF EMBODIMENT

Described below is an embodiment of a lathe of the present invention.

Lathe Configuration

First, the configuration of the lathe of this embodiment is described.FIG. 1shows a perspective view of the lathe of this embodiment.FIG. 2shows a front view of the same lathe.FIG. 3shows an enlarged view of frame III ofFIG. 2.FIG. 4shows an exploded perspective view of the right section of the same lathe.

As shown inFIGS. 1 to 4, lathe1is provided with a left-right pair of headstocks2, a left-right pair of tool rests3, a left-right pair of spindle motors4, bed5, a left-right pair of slide sections6, and a left-right pair of brackets7. Lathe1takes a symmetrical form in which two lathes are joined across the boundary of a joint of a left-right pair of widthwise extending sections500which are described below.

As shown inFIG. 1andFIG. 2, bed5is a cast iron structure. Bed5is provided with bed main body50, a left-right pair of headstock attaching sections51, a left-right pair of slide attaching sections52, a left-right pair of motor attaching sections53, and a front-rear pair of linking members54.

Bed main body50is provided with a left-right pair of bed divided bodies50L and50R. In other words, bed main body50is divided into left and right sections. Bed divided bodies50L and50R are respectively provided with a widthwise extending section500and a lengthwise extending section501.

The left-right pair of widthwise extending sections500respectively extend in a left-right direction (horizontal direction). The left-right pair of widthwise extending sections500contact in the left-right direction. The front-rear pair of linking members54are attached to the both the front and rear sides of the boundary section (joint section) of the left-right pair of widthwise extending sections500. The front-rear pair of linking members54link the left-right pair of widthwise extending sections500.

The left-right pair of lengthwise extending sections501respectively extend up from the widthwise extending section500. As shown inFIG. 3, the right side lengthwise extending section501is provided with an inner surface501aand an outer surface501b. Inner surface501aand outer surface501bare each flat. Inner surface501aand outer surface501bare inclined to the right side (left-right direction outside) by angle φ (for example, 15 degrees) with respect to a vertical direction. The slant direction (angle φ direction) length of inner surface501ais longer than that of outer surface501b. The left side of lengthwise extending section501and the right side of lengthwise extending section501have the same configuration. The left side of lengthwise extending section501and the right side of lengthwise extending section501are arranged to be symmetrical.

Left-right pair of headstock attaching sections51are respectively arranged on the upper surface of lengthwise extending section501. As shown inFIG. 3, the right side headstock attaching section51is provided with left-right pair of attaching surfaces510. Left-right pair of attaching surfaces510are each flat. The left side (inside in the left-right direction) attaching surface510is arranged above the right side (outside in the left-right direction) attaching surface510. Attaching surface510is slanted to the right side (outside in the left-right direction) by angle θ (for example, 15 degrees) with respect to a left-right direction. In other words, as shown inFIG. 2, slanted to the right side of tool rest3by angle θ with respect to the direction in which headstock2and tool rest3are lined up (the direction in which the blade tip of the tool contacts the work during work machining). The left side headstock attaching section51and the right side headstock attaching section51have the same configuration. The left side headstock attaching section51and the right side headstock attaching section51are arranged to be symmetrical.

As shown inFIG. 1andFIG. 2, left-right pair of slide attaching sections52are arranged on the upper surface outside in the left-right direction of widthwise extending section500. Left-right pair of slide attaching sections52are arranged outside in the left-right direction of left-right pair of headstock attaching sections51. Also, for tool rest3to be attached to the upper surface of slide section6described later, left-right pair of slide attaching sections52are arranged below left-right pair of headstock attaching sections51. Right side slide attaching section52is slanted to the left side (inside in the left-right direction) with respect to the left-right direction. In other words, the right side slide attaching section52is slanted to the side of headstock2on the right side with respect to the direction in which headstock2and tool rest3are lined up so that work chips do not get on the upper surface of the first lower slide60described later. The left side slide attaching section52has the same configuration as the right side slide attaching section52. The left side slide attaching section52is arranged to be symmetrical with the right side slide attaching section52.

As shown inFIG. 4, the left-right pair of motor attaching sections53are respectively arranged on the rear side of lengthwise extending sections50. Motor attaching section53is provided with a left-right pair of attaching ribs.

As shown inFIG. 1andFIG. 2, left-right pair of headstocks2are respectively arranged above headstock attaching section51. As shown inFIG. 3, the right side headstock2is provided with spindle20and a left-right pair of flanges21. Spindle20extends in a front-rear direction. Left-right pair of flanges21are each thin and flat. The left side (inside in the left-right direction) flange21is arranged above the right side (outside in the left-right direction) flange21. Flanges21are slanted to the right side (the outside in the left-right direction) by angle θ with respect to the left-right direction. In other words, as shown inFIG. 2, slanted to the right side of tool rest3by angle θ with respect to the direction in which headstock2and tool rest3are lined up (the direction in which the blade tip of the tool contacts the work during work machining). The left side flange21is attached to the left side attaching surface510. The right side flange21is attached to the right side attaching surface510. The left side headstock2has the same configuration as the right side headstock2. The left side headstock2is arranged to be symmetrical with the right side headstock2.

As shown inFIG. 1,FIG. 2andFIG. 4the left-right pair of slide sections6are respectively arranged above slide attaching sections52. Slide section6is provided with first lower slide60, shared slide61, and second slide62. First lower slide60is arranged on slide attaching section52. First lower slide60extends in a front-rear direction. Shared slide61is provided with first slide610and second lower slide611. First slide610can slide in a front-rear direction along first lower slide60. Second lower slide611is arranged above first slide610. Second lower slide611extends in a left-right direction. Second slide62can slide in a left-right direction along second lower slide611.

The left-right pair of tool rests3are respectively arranged above slide sections6. Tool rests3can be moved in front-rear and left-right directions by slide section6. Tool rest3is provided with tool rest main body30and turret31. Tool rest main body30is arranged on the upper surface of the second slide62. Turret31is arranged on the front surface of tool rest main body30. Turret31is intermittently rotatable at a specific angle by tool rest main body30. Multiple tools (not shown) are attached to turret31.

As shown inFIG. 2, rotation center line A1of spindle20and rotation center line A2of turret31both extend in a front-rear direction. In other words, rotation center line A1of spindle20and rotation center line A2of turret31are parallel to each other. Rotation center line A1of spindle20and rotation center line A2of turret31are lined up in a left-right direction.

As shown inFIG. 4, left-right pair of brackets7are respectively attached to motor attaching sections53. Left-right pair of spindle motors4are respectively attached to brackets7. The moving power of spindle motor4is transmitted to spindle20via a belt (not shown).

Lathe Operation

Next, the operation of the lathe of this embodiment is described.FIG. 5shows a front view of the right side portion of a conventional lathe.FIG. 6shows a front view of the right side portion of the lathe of this embodiment. The shape after thermal deformation is shown by hatching.FIG. 7shows the relative displacement between the spindle and turret due to thermal deformation. The spindle center and turret center are shown by a solid line circle (◯) and a solid line triangle (Δ) respectively. The spindle center for a conventional lathe is shown by a dotted line circle (◯). Also, inFIGS. 5 to 7, for ease of understanding, the thermal deformation amount is exaggerated.

In a conventional lathe, angles φ and θ shown inFIG. 3are both zero degrees. In other words, as shown inFIG. 5, left-right pair of attaching surfaces510each extend in a horizontal direction. Also, left-right pair of flanges21are lined up in a horizontal direction. Therefore, in a conventional lathe, headstock2is not slanted to the tool rest3side.

During machining of work, the heat from spindle motor4, spindle20, slide section6and so on is transmitted to bed5. Here, as shown inFIG. 2, bed5is provided with reduced thickness section502such that there is a height difference between headstock attaching section51and slide attaching section52. Bed5thermally deforms in the direction in which angle α of reduced thickness section502opens. In other words, widthwise extending section500tries to move right and down (down and outside in the left-right direction). Due to this, slide section6, tool rest3, and consequently the blade tip of the tools also try to move right and down. Conversely, lengthwise extending section501tries to move left and down (down and inside in the left-right direction). Due to this, headstock2also tries to move left and down. However, in actuality lathe1is arranged on a factory floor. Due to this, as shown by arrow Y1inFIG. 5, bed divided body50R deforms in an arc (the center of curvature of the arc is on the floor side). In this way, due to the thermal deformation (bending deformation) caused by reduced thickness section502of bed5, tool rest3and headstock2move in a direction away from each other drawing the path of the arc.

Also, in addition to the above bending deformation, bed5thermally deforms in an overall way. For example, as shown by arrow Y2inFIG. 5, lengthwise extending section501stretches mainly upwards. Due to this, headstock2and lengthwise extending section501both move up. Also, as shown by arrow Y3inFIG. 5, widthwise extending section500stretches right and up (up and outside in the left-right direction). Due to this, slide section6, tool rest3, and consequently the blade tip of the tools also move right and up along with widthwise extending section500. In this way, as shown by arrows Y2and Y3inFIG. 5, due to the overall thermal deformation (overall deformation) of bed5, tool rest3and headstock2move in a direction away from each other and each moves up.

In this way, the relative displacement of headstock2and tool rest3is roughly the combined displacement of the displacement due to bending deformation shown by arrow Y1(displacement caused by reduced thickness section502) and the displacement due to overall deformation shown by Y2and Y3(displacement caused by bed5overall). Due to this, as shown inFIG. 7, with a conventional lathe, a relative displacement L1arises between the dotted line circle (◯) that is the spindle center and the solid line triangle (Δ) that is the turret center.

In contrast, with the lathe of this embodiment, angle θ shown inFIG. 3is set such that 0 degrees<θ<90 degrees. Also, angle φ shown inFIG. 3is set such that 0 degrees<φ<90 degrees. In other words, as shown inFIG. 6, left-right pair of attaching surfaces510respectively slant to the right side by angle θ with respect to a horizontal direction. Also, left side flange21is arranged above right side flange21. In this way, in the lathe of this embodiment, headstock2is slanted to the tool rest3side.

During work machining, the same as a conventional lathe, due to the thermal deformation (bending deformation) caused by reduced thickness section502of bed5, as shown by arrow Y1inFIG. 6, tool rest3and headstock2move in a direction away from each other drawing the path of the arc. Also, the same as a conventional lathe, due to the overall thermal deformation (overall deformation) of bed5, as shown by arrow Y3inFIG. 6, slide section6, tool rest3, and consequently the blade tip of the tools also move right and up along with widthwise extending section500.

However, as shown inFIG. 3, widthwise extending section501stretches in an angle φ direction (right and up) with respect to an up-down direction (vertical direction). In other words, as shown inFIG. 3, the slant direction length for inner surface501ais longer than that for outer surface501b. Due to this, the stretch amount for the inner surface501aside is larger than that for the outer surface501bside. As shown by arrow Y4inFIG. 6, lengthwise extending section501stretches right and up by the difference of this stretch amount. Therefore, headstock2and lengthwise extending section501both move right and up. It follows that, as shown inFIG. 7, a relative displacement L2arises between the solid line circle (◯) that is the spindle center and the solid line triangle (Δ) that is the turret center.

As shown inFIG. 7, relative displacement L2is smaller than relative displacement L1by the amount set by angles φ and θ shown inFIG. 3. In other words, the relative displacement due to thermal deformation for the lathe of this embodiment is smaller than that for a conventional lathe. Also, with the lathe of this embodiment, the movement direction of the spindle center (right and up) includes a right component. Due to this, for the left-right direction, the machining point of the work (the position at which the blade tip makes contact) can be moved to the tool blade tip side.

Effects

Next, effects of the lathe of this embodiment are described. According to the lathe of this embodiment, as shown inFIG. 2andFIG. 3, angles φ and θ are set. In other words, headstock2is attached to headstock attaching section51slanted to the tool rest3side with respect to the direction in which headstock2and tool rest3are lined up (the direction in which the blade tip of the tool contacts the work during work machining). Due to this, as shown inFIGS. 5 to 7, compared to a case in which headstock2is attached to headstock attaching section51not slanted to the tool rest3side, when thermal deformation occurs, headstock2moves more easily in a direction towards tool rest3. In other words, it is easier for headstock2to be displaced such that the displacement amount of the above-mentioned slide section6, tool rest3, and tool blade tip (the displacement amount in the direction moved away from headstock2) is canceled out. Accordingly, the relative displacement of headstock2and tool rest3due to thermal deformation can be made smaller. In particular, the relative displacement between headstock2and tool rest3can be made smaller in the direction of the diameter of spindle20(the direction of the diameter of the work). This means that the thermal displacement amount in the direction of the machining diameter is small for lathe1.

Also, to correct the relative displacement amount of headstock2and tool rest3due to thermal deformation, a displacement correction amount must be entered into the machining program when machining work. According to lathe1of this embodiment, the frequency of entering a displacement correction amount can be reduced. Also, the displacement correction amount can be made smaller.

For example, in cases in which machining time is long, the relative displacement amount of headstock2and tool rest3due to thermal deformation is large. Also, the relative displacement amount of headstock2and tool rest3due to thermal deformation is large before and after breaks (stops in machining). Even for cases such as these, according to lathe1of this embodiment, the relative displacement of the headstock and tool rest due to thermal deformation can be made smaller. Due to this, the frequency of entering a displacement correction amount can be reduced. Also, the displacement correction amount can be made smaller. Also, in cases in which the required dimensional accuracy for the work is low (when the dimensional variance in the work is large enough with respect to the thermal displacement amount of the lathe), entering a displacement correction amount is no longer required. Also, according to lathe1of this embodiment, it is not necessary to arrange a mechanism for achieving anisotropy in the direction of the thermal deformation on bed5. Therefore, the construction is simple.

Also, as shown inFIG. 2, rotation center line A1of spindle20and rotation center line A2of turret31are arranged parallel to each other. Due to this, the left-right direction width (the dimension in the direction in which headstock2and tool rest3are lined up) of lathe1can be made smaller.

Also, as shown inFIG. 2, rotation center line A1of spindle20and rotation center line A2of turret31are arranged at the same height. Also, as shown inFIG. 4, second slide62can slide in a left-right direction along second lower slide611. Due to this, turret31can be slid in a left-right direction with respect to spindle20while maintaining a parallel state between the rotation center lines A1and A2. Also, as shown inFIG. 1andFIG. 2, bed main body50is divided into left and right sections. Due to this, machining vibrations of the left-right pair of spindles20during machining are harder to transmit to each other.

Other Embodiments

An embodiment of a lathe of the present invention was described above. However, embodiments are not limited to the above-described embodiments. People skilled in the art may implement various modified or improved embodiments.

Angle α shown inFIG. 2merely needs to be such that 0 degrees<α<90 degrees. In other words, lengthwise extending section501merely needs to extend in a direction intersecting widthwise extending section500. Angle φ shown inFIG. 3merely needs to be such that 0 degrees<φ<90 degrees. Also, angle θ merely needs to be such that 0 degrees<θ<90 degrees. In other words, headstock2merely needs to be slanted to the tool rest3side with respect to the direction in which headstock2and tool rest3are lined up. Also, the lathe of the present invention may be embodied as a horizontal lathe, a frontal lathe, a vertical lathe and so on.

Also, the form of thermal deformation shown inFIGS. 5 to 7(deformation direction, deformation amount, and so on) is not limited. The form of thermal deformation changes based on the shape, position, quantity and so on of each member (headstock2, tool rest3, spindle motor4, bed5, slide section6and so on).