Patent Description:
A press brake is provided with a back gauge device for positioning a workpiece in the front-rear direction with respect to a lower tool (see Patent Literatures <NUM> to <NUM>). The outline of the configuration of the back gauge device will be described below.

A pair of support blocks separated in the lateral direction are provided on the back side of a lower table in a main frame, and the pair of support blocks are first and second support blocks. Elevating members extending vertically are provided to the respective support blocks so as to be able to ascend and descend, and the pair of elevating members are first and second elevating members. Further, a stretch extending in the lateral direction is provided between the upper end portion of the first elevating member and the upper end portion of the second elevating member. One end side of the stretch in the lateral direction is fixed to the upper end portion of the first elevating member, and the other end side of the stretch in the lateral direction is fixed to the upper end portion of the second elevating member. Further, a plurality of abutting members are provided to the stretch, and each of the abutting members includes an abutting surface, on the distal end side thereof, against which the end surface of the plate-shaped workpiece can be abutted. Each of the abutting members is configured to be movable in the lateral direction and the front-rear direction with respect to the main frame. The abutting surface of each of the abutting members is positioned at a height position corresponding to the height of the lower tool by an elevating operation of the pair of elevating members.

The back gauge device is divided into a first type that performs the elevating operation of the pair of elevating members by driving two motors (see Patent Literature <NUM> and Patent Literature <NUM>), and a second type that performs the elevating operation of the pair of elevating members by driving one motor (see Patent Literature <NUM>). Since the number of motors is reduced in the second type back gauge device, the cost of the press brake can be lowered as compared with the first type back gauge device. Among the configurations of the second type back gauge device, the configuration for ascending and descending the pair of elevating members will be described below.

Ball screws (screw bolts in Patent Literature <NUM>) extending vertically are provided to respective ends of the stretch in the lateral direction so as to be hanged down. A nut member is provided on the upper end side of each of the elevating members (upper and lower guide pins in Patent Literature <NUM>) via a separate member (a front-rear moving beam member in Patent Literature <NUM>), and each of the nut members is screwed into each of the ball screws. A motor (a servo motor for vertical movement in Patent Literature <NUM>), which causes a pair of nuts to be rotated, is provided on the upper end side of the first elevating member. An output shaft of the motor is interlocked and connected to the pair of nut members via a chain or a timing belt.

The second type back gauge device includes the pair of ball screws and the pair of nut members. In other words, the second type back gauge device includes two ball screw mechanisms for elevation, each of which includes the ball screw and the nut member. Therefore, in the second type back gauge device, adjustment for synchronizing the two ball screw mechanisms for elevation is required, which causes a problem that the adjustment work of the back gauge device requires a lot of time and effort.

A press brake according to the present invention is defined in independent claim <NUM>. The dependent claim defines a preferred embodiment.

Here, the pair of support blocks, the pair of elevating members, the stretch, the support mechanism, and the abutting member constitute a part of a back gauge device for positioning a workpiece in the front-rear direction with respect to a lower tool installed on the lower table.

According to the present invention, the one end side of the stretch in the lateral direction is connected to the upper end portion of the first elevating member. The other end side of the stretch in the lateral direction is connected to the upper end portion of the second elevating member. The support mechanism that supports the stretch from below is provided to the first elevating member. Therefore, by providing only one ball screw mechanism for elevation, which includes the ball screw and the nut member, to the back gauge device, the pair of elevating members can be ascended and descended by the driving of one motor. Therefore, it is possible to simplify the adjustment work of the back gauge device while reducing the cost of the press brake.

Hereinafter, the present embodiment will be described with reference to <FIG>.

Note that in the description and the claims of the present application, the term "provided" means not only directly provided but also indirectly provided via another member. The term "lateral direction" is one of the horizontal directions, which is a lateral direction of the press brake, and is also referred to as the Y-axis direction. The phrase "inside in the lateral direction" means the center side of the press brake in the lateral direction. The term "front-rear direction" is a horizontal direction orthogonal to the lateral direction, which is a depth direction of the press brake, and is also referred to as the L-axis direction. In the drawings, "FF" indicates the front direction, "FR" indicates the rear direction, "L" indicates the left direction, "R" indicates the right direction, "U" indicates the upward direction, and "D" indicates the downward direction.

As shown in <FIG>, a press brake <NUM> according to the present embodiment is a working machine that bends a plate-shaped workpiece (a sheet metal) W by the collaboration between an upper tool (punch tool) <NUM> and a lower tool (die tool) <NUM>. The press brake <NUM> includes with a main frame <NUM>, and the main frame <NUM> includes a pair of side plates <NUM> that are separated and opposed to each other in the lateral direction, and a plurality of connecting members (not shown) that integrally connect the pair of side plates <NUM>. The pair of side plates <NUM> are first (left side) and second (right side) side plates <NUM>.

A lower table <NUM> extending in the lateral direction is provided at the lower part of the front surface side (the front side) of the main frame <NUM>. A lower tool holder <NUM>, which retains the lower tool <NUM> so as to be installable and removeable, is provided on the upper side of the lower table <NUM>. Further, an upper table <NUM> extending in the lateral direction is provided at the upper part of the front surface side of the main frame <NUM> so as to be able to ascend and descend (so as to be vertically movable). The upper table <NUM> is ascended and descended by the driving of an elevating hydraulic cylinder (not shown) or an elevating motor (not shown) as an elevating actuator for a table provided at an appropriate position on the main frame <NUM>. An upper tool holder <NUM>, which retains the upper tool <NUM> so as to be installable and removable, is provided on the lower side of the upper table <NUM>. In lieu of configuring the upper table <NUM> so as to be able to ascend and descend, the lower table <NUM> may be configured so as to be able to ascend and descend.

A back gauge device <NUM> for positioning the workpiece W in the front-rear direction with respect to the lower tool <NUM> is provided on the back side (the rear side) of the lower table <NUM> in the main frame <NUM>. In the schematic partial cross-sectional view of <FIG>, the back gauge device <NUM> provided inside in the lateral direction of the second (right side) side plate <NUM> is illustrated on the back side (the rear side) of the lower table <NUM>. The specific configuration of the back gauge device <NUM> will be described below.

As shown in <FIG>, a pair of support blocks (guide blocks) <NUM>, which are separated and opposed to each other in the lateral direction, are provided on the back side of the lower table <NUM> in the main frame <NUM>. The pair of support blocks <NUM> are first (left side) and second (right side) support blocks <NUM>. The first support block <NUM> is fixed to the first side plate <NUM>, and the second support block <NUM> is fixed to the second side plate <NUM>. Each of the support blocks <NUM> has, on the back side thereof, a guide portion <NUM> extending vertically. Each of the support blocks <NUM> includes, inside in the lateral direction thereof, a protrusion 30p that protrudes in the rear direction. Further, an elevating member <NUM> extending vertically is provided via a slide rail <NUM> to the guide portion <NUM> of each of the support blocks <NUM> so as to be able to ascend and descend. The pair of elevating members <NUM> are first (left side) and second (right side) elevating members <NUM>. The first elevating member <NUM> includes, on the back side thereof, two protrusions 32p and 32b that are vertically separated. The second elevating member <NUM> includes, on the lower end side thereof, an extending portion 32e extending downward. Note that the drawings of the present application show, as an example, a state in which the pair of elevating members <NUM> are positioned at the lowest position.

A ball screw <NUM> extending vertically is provided between the two protrusions 32p and 32b of the first elevating member <NUM> so as to be rotatable. An elevating motor <NUM> that causes the ball screw <NUM> to rotate is provided, via a bracket <NUM>, to the protrusion 32b of the first elevating member <NUM>. An output shaft of the elevating motor <NUM> is interlocked and connected to the ball screw <NUM> via two pulleys <NUM> and <NUM> and a timing belt <NUM>. The ball screw <NUM> is ascended and descended while being rotated by the driving of the elevating motor <NUM>. Further, a nut member <NUM> screwed into the ball screw <NUM> is provided to the protrusion 30p of the first support block <NUM>. The back gauge device <NUM> includes one ball screw mechanism for elevation, which includes the ball screw <NUM> and the nut member <NUM>. Note that in lieu of providing the ball screw <NUM> to the first elevating member <NUM> so as to be rotatable, the ball screw <NUM> may be provided to the first support block <NUM> so as to be rotatable. In this case, the nut member <NUM> is provided not to the first support block <NUM> but to the first elevating member <NUM>.

An electromagnetic brake <NUM> that secures the ball screw <NUM> in a nonrotatable manner is provided to the protrusion 32p of the first elevating member <NUM>. The electromagnetic brake <NUM> is configured to secure the ball screw <NUM> by a braking force in a nonrotatable manner when the power of the press brake <NUM> is turned off. Note that the electromagnetic brake <NUM> is a body separated from the elevating motor <NUM>, but the elevating motor <NUM> may include the electromagnetic brake. The back gauge device <NUM> may include another brake (not shown) that secures the ball screw <NUM> in a nonrotatable manner in lieu of the electromagnetic brake <NUM>.

A plurality of tension springs <NUM> are provided in parallel between the protrusion 30p of the second support block <NUM> and the extending portion 32e of the second elevating member <NUM>, as balancers that reduce gravity acting on the second elevating member <NUM>. The plurality of tension springs <NUM> are urging members that urge the second elevating member <NUM> upward. The upper end portion of each of the tension springs <NUM> is locked to the protrusion 30p of the second support block <NUM> via a bracket <NUM>, and the lower end portion of each of the tension springs <NUM> is locked to the lower end portion of the extending portion 32e of the second elevating member <NUM>.

As shown in <FIG>, a square pipe-shaped stretch <NUM> extending in the lateral direction is provided between the upper end portion of the first elevating member <NUM> and the upper end portion of the second elevating member <NUM>. The stretch <NUM> includes connecting portions 56j and 56c on one end side and the other end side in the lateral direction thereof, respectively. The connecting portion 56j of the stretch <NUM> is connected, so as to be rotationally movable (swingable), to the upper end portion of the first elevating member <NUM> via a first connecting bolt <NUM> as a first connecting pin. The first connecting bolt <NUM> is screwed into the upper end portion of the first elevating member <NUM>. The connecting portion 56c of the stretch <NUM> is connected, so as to be rotationally movable, to the upper end portion of the second elevating member <NUM> via a second connecting bolt <NUM> as a second connecting pin. The second connecting bolt <NUM> is screwed into the upper end portion of the second elevating member <NUM>.

A support mechanism <NUM> that supports the stretch <NUM> from below is provided on the upper end side of the first elevating member <NUM>. The support mechanism <NUM> includes a support base <NUM> provided on the upper end side of the first elevating member <NUM> and extending inside in the lateral direction. The support mechanism <NUM> includes an adjusting screw <NUM> that is provided by being screwed into a distal end portion of the support base <NUM> and that contacts (supports) the stretch <NUM> from below, and upper and lower lock nuts <NUM> and <NUM> that prevent the adjusting screw <NUM> from being loosened. The support mechanism <NUM> adjusts levelness of the stretch <NUM> when the stretch <NUM> moves rotationally around the first connecting bolt <NUM>.

As shown in <FIG>, <FIG>, and <FIG>, a pair of Y-axis sliders <NUM> is provided to the stretch <NUM> so as to be movable in the lateral direction via a plurality of guide rails <NUM>. Each of the Y-axis sliders <NUM> extends in the front-rear direction. A Y-axis motor <NUM>, which causes each of the Y-axis sliders <NUM> to move in the lateral direction with respect to the stretch <NUM>, is provided on the back side of each of the Y-axis sliders <NUM>. A rack member <NUM> extending in the lateral direction is provided on the back surface of the stretch <NUM>. A pinion <NUM> is provided to an output shaft of each of the Y-axis motors <NUM>, and each of the pinions <NUM> is engaged with the rack member <NUM>. Note that as an example, the drawings of the present application show a state in which the pair of Y-axis sliders <NUM> are most separated in the lateral direction.

An L-axis slider <NUM> is provided on the upper surface of each of the Y-axis sliders <NUM> so as to be movable in the front-rear direction via a pair of guide rails <NUM>. An L-axis motor <NUM>, which causes each of the L-axis sliders <NUM> to move in the front-rear direction with respect to each of the Y-axis sliders <NUM>, is provided at the rear end portion of each of the Y-axis sliders <NUM>. A ball screw <NUM> extending in the front-rear direction is provided on the upper surface of each of the Y-axis sliders <NUM> so as to be rotatable, and each of the ball screws <NUM> is interlocked and connected to an output shaft of each of the L-axis motors <NUM> via a coupling <NUM>. A nut member <NUM> is provided to the rear end portion of each of the L-axis sliders <NUM>, and each of the nut members <NUM> is screwed into each of the ball screws <NUM>.

As shown in <FIG>, <FIG>, and <FIG>, an abutting base <NUM> is provided on the upper surface of each of the L-axis sliders <NUM>, and a mounting shaft <NUM> is provided to a distal end portion of each of the abutting bases <NUM>. An abutting member <NUM>, which has a known configuration that is shown in Patent Literature <NUM>, is provided to each of the mounting shafts <NUM>. In other words, the pair of abutting members <NUM> are provided to the stretch <NUM> via the pair of Y-axis sliders <NUM>, the pair of L-axis sliders <NUM>, and the like. Each of the abutting members <NUM> includes, on a distal end side thereof, an abutting surface 98f against which an end surface Wf of the workpiece W can be abutted. Each of the abutting members <NUM> is configured to be movable in the lateral direction and the front-rear direction with respect to the main frame <NUM>. Each of the abutting members <NUM> moves in the lateral direction integrally with the Y-axis slider <NUM> with respect to the main frame <NUM> by the driving of the Y-axis motor <NUM>. Each of the abutting members <NUM> moves in the front-rear direction integrally with the L-axis slider <NUM> with respect to the main frame <NUM> by the driving of the L-axis motor <NUM>. Each of the abutting members <NUM> is configured to be able to be installed to and removed from each of the mounting shafts <NUM> and to be able to be folded up with an axial center of each of the mounting shafts <NUM> as a center.

Subsequently, the operation and effect of the press brake <NUM> according to the present embodiment will be described.

The pair of elevating members <NUM> are ascended and descended by the driving of the elevating motor <NUM>. Thereby, the stretch <NUM> is ascended and descended integrally with the pair of elevating members <NUM>, which causes the abutting surface 98f of each of the abutting members <NUM> to be positioned at a height position corresponding to the lower tool <NUM>. Further, each of the abutting members <NUM> is moved in the lateral direction integrally with each of the Y-axis sliders <NUM> by the driving of each of the Y-axis motors <NUM>. Thereby, the interval in the lateral direction between the pair of abutting members <NUM> is adjusted according to a bending length of the workpiece W. Further, each of the abutting members <NUM> is moved in the front-rear direction integrally with each of the L-axis sliders <NUM> by the driving of each of the L-axis motors <NUM>, which causes the abutting surface 98f of each of the abutting members <NUM> to be positioned at a predetermined position in the front-rear direction.

After that, the workpiece W is moved in the rear direction and the end surface Wf of the workpiece W is abutted against the abutting surfaces 98f of the pair of abutting members <NUM>. Thereby the workpiece W is positioned in the front-rear direction with respect to the lower tool <NUM>. Then, the upper table <NUM> is lowered, which causes the workpiece W to be bent by the collaboration between the upper tool <NUM> and the lower tool <NUM>. At this time, since each of the abutting members <NUM> is folded up with the axial center of each of the mounting shafts <NUM> as a center, it is possible to prevent damage to the abutting member <NUM> and the like, which is caused by the folding-up of the workpiece W. Note that after the workpiece W is bent, the upper table <NUM> is raised to return to the original state.

In the press brake <NUM>, as described above, the connecting portion 56j of the stretch <NUM> is connected, so as to be rotationally movable, to the upper end portion of the first elevating member <NUM> via the first connecting bolt <NUM>. The connecting portion 56c of the stretch <NUM> is connected, so as to rotationally movable, to the upper end portion of the second elevating member <NUM> via the second connecting bolt <NUM>. The second connecting bolt <NUM> is screwed into the upper end portion of the second elevating member <NUM>. The support mechanism <NUM> that supports the stretch <NUM> from below is provided on the upper end side of the first elevating member <NUM>. The plurality of tension springs <NUM> that reduce the gravity acting on the second elevating member <NUM> are provided in parallel between the protrusion 30p of the second support block <NUM> and the extending portion 32e of the second elevating member <NUM>. Therefore, by providing only one ball screw mechanism for elevation, which includes the ball screw <NUM> and the nut member <NUM>, to the back gauge device <NUM>, the pair of elevating members <NUM> can be ascended and descended by the driving of one elevating motor <NUM>.

Prior to bending of the workpiece W, the power of the press brake <NUM> is turned off and the ball screw <NUM> is secured in a nonrotatable manner by the electromagnetic brake <NUM>. Then, the stretch <NUM> is moved rotationally around the first connecting bolt <NUM> so that the stretch <NUM> becomes level by a rotary operation of the adjusting screw <NUM> in a state in which the gravity acting on the second elevating member <NUM> is reduced by the plurality of tension springs <NUM>. As a result, the levelness of the stretch <NUM> can be easily adjusted.

According to the present embodiment, as described above, by providing only one ball screw mechanism for elevation to the back gauge device <NUM>, the pair of elevating members <NUM> can be ascended and descended by the driving of one elevating motor <NUM> and the levelness of the stretch <NUM> can be easily adjusted. Therefore, according to the present embodiment, it is possible to simplify the adjustment work of the back gauge device <NUM> while reducing the cost of the press brake <NUM>.

Claim 1:
A press brake (<NUM>), comprising:
a pair of support blocks (<NUM>) provided on a back side of a lower table (<NUM>) in a main frame (<NUM>) and separated in a lateral direction;
elevating members (<NUM>) each provided to respective one of the pair of support blocks (<NUM>) so as to be able to ascend and descend and extending vertically;
a ball screw (<NUM>) provided so as to be rotatable to a first elevating member of a pair of the elevating members (<NUM>) or a first support block of the pair of support blocks (<NUM>), extending vertically, and configured to be rotated by a driving of a motor (<NUM>);
a nut member (<NUM>) provided to the first support block (<NUM>) or the first elevating member (<NUM>) and screwed into the ball screw (<NUM>);
a stretch (<NUM>) extending in the lateral direction, one end side of the stretch (<NUM>) in the lateral direction being connected to an upper end portion of the first elevating member (<NUM>) and another end side of the stretch (<NUM>) in the lateral direction being connected to an upper end portion of a second elevating member (<NUM>) of the pair of elevating members (<NUM>);
an abutting member (<NUM>) provided to the stretch (<NUM>), the abutting member (<NUM>) including, on a distal end side, an abutting surface (98f) against which an end surface (Wf) of a plate-shaped workpiece (W) can be abutted, the abutting member (<NUM>) being configured to be movable in a front-rear direction with respect to the main frame (<NUM>); and
a support mechanism (<NUM>) provided to the first elevating member (<NUM>) so as to support the stretch (<NUM>) from below,
characterized in that
the press brake (<NUM>) further comprises a brake (<NUM>) configured to secure the ball screw (<NUM>) in a nonrotatable manner, wherein
one end side of the stretch (<NUM>) in the lateral direction is connected to the upper end portion of the first elevating member (<NUM>) via a first connecting pin (<NUM>) so as to be rotationally movable, and another end side of the stretch (<NUM>) in the lateral direction is connected to the upper end portion of the second elevating member (<NUM>) via a second connecting pin (<NUM>) so as to be rotationally movable, and
the support mechanism (<NUM>) includes
a support base (<NUM>) provided to the first elevating member (<NUM>), and
an adjusting screw (<NUM>) provided by being screwed into the support base (<NUM>) so as to contact the stretch (<NUM>) from below.