Abstract:
A tool system for brake forming having a punch or a die and at least one insert. In one embodiment, two inserts are removably attached to a die. The die has a defined shape running along a longitudinal axis. Each insert has a protrusion with a particular cross-sectional shape running along the same longitudinal axis. The die has two cavities, each cavity having a cross-sectional shape matching the cross-sectional shape of the protrusion of one of the inserts. In another embodiment, the die has two protrusions and each insert has a cavity for receipt of one of the protrusions of the die. When one of the protrusions is inserted into one of the cavities, the insert is removably fixed to the die. At least one surface of each insert corresponds to and combines with the defined shape of the die, forming a bending surface against which a sheet of metal is formed. After press braking, the sheet of metal is substantially conformed to the defined shape of the die. In another embodiment, an insert is removably attached to a punch such that the insert forms the entire surface of the punch system that contacts the sheet of metal to be shaped during press braking. The inserts are positioned such that they encounter most of the wear caused by the brake forming, whereas the punch and the die encounter only minimal wear. As a result, the inserts are inexpensively repaired or replaced when needed, but the punch and the die remain in good condition during extended use.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to the field of mechanical metal deformation processes, and more particularly to brake forming. 
   The process of brake forming involves placement of a piece of sheet metal along a die and pressing a punch downward onto the die to form the sheet metal along a straight axis in a desired shape. Many shapes can result, but common shapes include a v-shape, channel-shape, and u-shape. 
   Press brake punches and dies are well known in the art, as are methods of making them. Because punches and dies repeatedly undergo significant forces during brake forming, they are generally made of hardened steel. Such steel must have sufficient hardness to provide the necessary strength and rigidity to maintain the effectiveness and shape of the punch and die over multiple uses. 
   A major problem with press brake tools is that they wear out quickly. After a certain number of uses, abrasion and galling cause deformation of the punch and the die. Because precision in brake forming is often critical, when the punch or the die begins to lose its shape, the press operator must make adjustments to the forming process, replace the punch or die, or repair the punch or die. Replacement and repair of punches and dies contribute to the costs of the brake forming process, as does having to shut the press down during the re-tooling. 
   It is therefore desired to develop a punch and a die that better resist wear from repeated use, but that do not significantly increase the costs of manufacture or decrease the performance of the press brake. In the past, dies have been created with inserts to decrease friction. For example, the invention of U.S. Pat. No. 3,914,972 includes a die having rotatable inserts made from an anti-friction material, such as TEFLON. However, being made from anti-friction material, these inserts cost more to produce, and must be replaced more often, than inserts made of harder, less expensive materials, such as steel. Further, because of the reduced hardness of such inserts, dies having these inserts may not be useable with some types of hardened sheet metal. 
   In addition, press brakes have been created in the past that include a removable punch insert and a removable die portion. For example, the invention of U.S. Pat. No. 5,878,619 includes such a system. However, these types of tool systems do not sufficiently reduce the expense of press braking. First, the removable punch insert does not comprise the entire bending surface of the punch, and therefore the punch itself undergoes wear from the press braking process and must be periodically repaired or replaced. In addition, the removable punch insert can be expensive to make because it is an intricate part that contains several different bending surfaces of different radii, each of which must be separately tooled to precise measurements. Second, the removable die portion does not sufficiently reduce expenses because it itself is the tool used to shape the metal, and is therefore susceptible to substantial wear. The removable die portion is expensive to repair or replace because it consists of the entire portion of the bending surface of the die and thus must be machined to the desired shape and radius. 
   SUMMARY 
   The present invention comprises a tool system for use in press braking and other types of mechanical metal deformation processes. In one embodiment, the tool system of the present invention comprises a die and two inserts. The die has a longitudinal axis and a defined shape along that axis. The die also has two cavities running along the longitudinal axis; each cavity has a cross-sectional shape. 
   Each insert has a longitudinal axis that corresponds to the longitudinal axis of the die. Additionally, each insert has a protrusion running along the longitudinal axis that has a cross-sectional shape. The cross-sectional shape of the protrusion of each insert matches the cross-sectional shape of at least one of the cavities of the die. These protrusions are inserted into the cavities in the die, causing a removably fixed mechanical interlock between each protrusion and each cavity. The interlock between each protrusion and each cavity is such that each insert is removably attached to the die. Therefore, after insertion, each insert is fixed onto the die, permitting little or no movement of the insert with respect to the die. 
   During operation of the press brake, the two inserts are removably attached to the die. At least one surface of each insert corresponds to and combines with the defined shape of the die to form the bending surface for shaping a sheet of metal. The sheet of metal is pressed against the bending surface by a press brake punch and consequently is conformed substantially to the shape of the bending surface. The defined shape of the die, and therefore the bending surface, may be substantially v-shaped, substantially u-shaped, or substantially channel-shaped. Alternatively, one of various other suitable shapes may be used. 
   In another embodiment of the present invention, the tool system comprises a die and two inserts, but the die has two protrusions running along the longitudinal axis of the die, with each protrusion having a cross-sectional shape. Each insert has a cavity running along the longitudinal axis of the die. The cavity of each insert has a cross-sectional shape that matches the cross-sectional shape of one of the protrusions of the die such that one protrusion of the die may be inserted into the cavity of each insert. As a result, each protrusion of the die and the cavity of each insert forms a removably fixed mechanical interlock. The two inserts are therefore removably attached to the die such that there is little or no movement of the inserts with respect to the die during operation of the press brake. 
   In another embodiment of the present invention, the tool system comprises a punch and an insert. The punch has a cavity running along the longitudinal axis of the punch, with the cavity having a cross-sectional shape. The insert has a protrusion along the same longitudinal axis. The protrusion has a cross-sectional shape that matches the cross-sectional shape of the cavity such that the protrusion of the insert may be inserted into the cavity of the punch to form a removably fixed mechanical interlock. The insert is therefore removably attached to the punch such that there is little or no movement of the insert with respect to the punch during operation of the press brake. In a further embodiment, the punch has a protrusion with a cross-sectional shape, and the insert has a cavity with a matching cross-sectional shape to form the removably fixed mechanical interlock. 
   Because the inserts are positioned such that they, rather than the punch or the die, undergo most of the wear during operation, wear on the punch or the die will be minimal. The punch or the die will need to be repaired or replaced only infrequently, thereby significantly lowering the costs of the press brake process. Replacing the inserts is a relatively quick, convenient, and inexpensive process that generally will restore the performance of the tool system to that of its first use. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a cross-sectional view of an embodiment of the present invention having a die and two inserts; 
       FIG. 2  shows a perspective view of the tool system of  FIG. 1  with one insert removed; 
       FIG. 3  shows a perspective view of one of the inserts of  FIG. 1 ; 
       FIG. 4  shows a cross-sectional view of an embodiment of the present invention having a die and one insert; 
       FIG. 5  shows a cross-sectional view of another embodiment of the present invention having a die and two inserts; 
       FIG. 6  shows a cross-sectional view of an embodiment of the present invention having a punch and an insert; 
       FIG. 7  shows a perspective view of another embodiment of the present invention having a punch and an insert, wherein the insert is shown detached from the punch; 
       FIG. 8  shows a cross-sectional view of another embodiment of the present invention having a die and inserts; and 
       FIG. 9  shows a cross-sectional view of another embodiment of the present invention having a die and inserts. 
   

   DETAILED DESCRIPTION 
   Referring now to  FIG. 1 ,  FIG. 2 , and  FIG. 3 , there is shown one embodiment of the present invention comprising die  12  and inserts  14  and  16 . Die  12  extends along longitudinal axis  18  and has defined shape  20  along longitudinal axis  18 . Defined shape  20  is used as part of a bending surface for shaping a sheet of metal during brake forming. Generally, during operation, a sheet of metal is placed on top of die  12 . A punch is pressed downward onto die  12  to substantially conform the sheet of metal to the shape of defined shape  20 . In the embodiment shown in  FIG. 1  and  FIG. 2 , defined shape  20  is substantially v-shaped, which will produce a metal piece having a substantial v-shape. However, the defined shape of a die of the present invention need not be substantially v-shaped. Other shapes are contemplated to be within the scope of the invention, including but not limited to a substantial u-shape (see  FIG. 8 ), a substantial channel-shape (see  FIG. 5 ), a substantial hat-channel shape (see  FIG. 9 ), a substantial closing-shape, a substantial single form-shape, a substantial double form-shape, a substantial radius-shape, a substantial wipe die-shape, a substantial offset-shape (see  FIG. 4 ), and a substantial flat-shape. 
   Persons of skill in the art will appreciate that die  12  may optionally include means  22  for attaching the die to a press brake system. Such attachments are well known in the art, and any method of attachment may be used and is contemplated to be within the scope of the invention. 
   Die  12  also comprises cavities  24  and  26  running along longitudinal axis  18 . Each of cavities  24  and  26  has a certain cross-sectional shape with respect to longitudinal axis  28  (see  FIG. 3 ) of insert  14  and insert  16 , respectively. In the embodiment of  FIG. 1  and  FIG. 2 , cavity  24  and cavity  26  have the same cross-sectional shape, namely a dove-tailed cross-sectional shape. However, as is explained in greater detail herein, the present invention includes dies having one or more cavities, with each of the cavities having the same or a different cross-sectional shape. 
   As previously mentioned, each of inserts  14  and  16  has longitudinal axis  28 . Longitudinal axis  28  corresponds to (is in the same direction as) longitudinal axis  18  of die  12 . Insert  14  comprises protrusion  30  for insertion into cavity  24 ; protrusion  30  has a cross-sectional shape that matches the cross-sectional shape of cavity  24 . Likewise, insert  16  comprises protrusion  32  for insertion into cavity  26 ; protrusion  32  has a cross-sectional shape that matches the cross-sectional shape of cavity  26 . 
   Cavity  24  and protrusion  30 , as well as cavity  26  and protrusion  32 , could have any one of many suitable cross-sectional shapes that are well known in the art, so long as the cross-sectional shape permits a removably fixed mechanical interlock between cavity  24  and protrusion  30  or between cavity  26  and protrusion  32 , respectively, when the insert is inserted into the die according to the present invention. The removably fixed mechanical interlock between cavity  24  and protrusion  30  removably attaches insert  14  and die  12 ; the removably fixed mechanical interlock between cavity  26  and protrusion  30  removably attaches insert  16  and die  12 . Therefore, by sliding protrusion  30  of insert  14  into cavity  24  of die  12 , insert  14  is removably attached to die  12 . Similarly, by sliding protrusion  32  of insert  16  into cavity  26  of die  12 , insert  16  is removably attached to die  12 . After insertion, each of insert  14  and insert  16  is fixed onto die  12 , permitting little or no movement of the insert with respect to the die. It will be appreciated by persons of skill in the art that the present invention includes alternative embodiments in which the positioning of the protrusions and the cavities are reversed. In these embodiments, at least one protrusion is positioned on the die and a cavity is positioned on each insert. The cross-sectional shape of each protrusion of the die matches the cross-sectional shape of a cavity of each insert such that, when the inserts are removably attached to the die as described herein, there is little or no movement of the insert with respect to the die. 
   Insert  14  further comprises surface  34 , which corresponds to a portion of defined shape  20  of die  12 . As shown more particularly in  FIG. 1  and  FIG. 3 , insert  16  further comprises surface  36 , which corresponds to a portion of defined shape  20  of die  12 . As such, surface  34  of insert  14 , surface  36  of insert  16 , and defined shape  20  of die  12  combine to form the bending surface against which the sheet of metal is pressed by a punch during operation. 
   Persons of skill in the art will appreciate that die  12  and inserts  14  and  16  may be made of any material with suitable strength and hardness to withstand the press braking process. Preferably, die  12  and inserts  14  and  16  are made of the same material, preferably hardened steel. However, insert  14 , insert  16 , or both inserts  14  and  16 , may be made of a material different than the material of which die  12  is made. Many methods and materials may be used to make die  12  and inserts  14  and  16 . For example, die  12  and inserts  14  and  16  may be comprised of D2 tool steel, heat treated to at least about 50 Rockwell, preferably to between about 55 Rockwell and about 60 Rockwell, then polished and ground. Inserts  14  and  16  and die  12  may be coated with a hardening material such as T.D. coating. T.D. coating is also known as thermal diffusion coating, thermoreactive diffusion coating, or Toyota diffusion coating. Such coatings are well known in the art and further assist the die and inserts in resisting wear and corrosion. 
   Die  10  may be created as a new product or may be created by machining a worn die for receipt of inserts  14  and  16 . 
   Insert  14 , insert  16 , or both inserts  14  and  16 , may be the same length as die  12  or may be of a different length. Preferably, insert  14  is the same length as insert  16 . Multiple inserts  14  or  16  may be aligned in an end-to-end fashion along longitudinal axis  18  to form a longer insert  14  or  16 , respectively. 
   Referring now to  FIG. 4 , there is shown another embodiment of the present invention which comprises die  120  and insert  140 . Die  120  has defined shape  200 , which is substantially offset-shaped. Die  120  further has cavity  240 , which has the cross-sectional shape of an inverted-T. Insert  140  comprises protrusion  300 , which has a cross-sectional shape that matches the inverted-T cross-sectional shape of cavity  240 . Insert  140  further comprises surface  340 , which corresponds to a portion of defined shape  200 . As such, surface  340  of insert  140  and defined shape  200  combine to form the bending surface against which the sheet of metal is pressed by a punch during operation. 
   Referring now to  FIG. 5 , there is shown another embodiment of the present invention which comprises die  420  and inserts  440  and  460 . Die  420  has defined shape  500 , which is substantially channel-shaped. Die  420  further has protrusions  540  and  560 , each of which has a cross-sectional shape, namely a dove-tailed cross-sectional shape. Insert  440  comprises cavity  600 , which has a cross-sectional shape that matches the cross-sectional shape of protrusion  540 . Similarly, insert  460  comprises cavity  620 , which has a cross-sectional shape that matches the cross-sectional shape of protrusion  560 . Insert  440  further comprises surface  640 , which corresponds to a portion of defined shape  500  of die  420 . Insert  460  further comprises surface  660 , which corresponds to a portion of defined shape  500  of die  420 . As such, surface  640  of insert  440 , surface  660  of insert  460 , and defined shape  500  of die  420  combine to form the bending surface against which the sheet of metal is pressed by a punch during operation. 
   Referring now to  FIG. 6 , there is shown another embodiment of the present invention which comprises punch  720  and insert  740 . Punch  720  has a longitudinal axis (not shown) and lateral axis  750 . Punch  720  further has width  760  along lateral axis  750  and cavity  770  along its longitudinal axis. Cavity  770  has a cross-sectional shape, which, in the embodiment shown in  FIG. 6 , is a substantially dove-tailed cross-sectional shape. 
   Persons of skill in the art will appreciate that punch  720  may optionally include means  775  for attaching the punch to a press brake system. Such attachments are well known in the art, and any method of attachment may be used and is contemplated to be within the scope of the invention. 
   Insert  740  has a longitudinal axis (not shown) that corresponds to (is in the same direction as) the longitudinal axis of punch  720 . Along its longitudinal axis, insert  740  has protrusion  780 . Protrusion  780  has a cross-sectional shape that matches the cross-sectional shape of cavity  770  of punch  720 . In the embodiment of  FIG. 6 , the cross-sectional shape of cavity  770  of punch  720  and of protrusion  780  of insert  740  is a substantially dove-tailed cross-sectional shape. However, those of skill in the art will appreciate that other suitable and well-known cross-sectional shapes, such as a substantially T-shaped cross-sectional shape or a substantially inverted-T cross-sectional shape, are contemplated to be within the scope of the invention, so long as the cross-sectional shape permits a removably fixed mechanical interlock between cavity  770  and protrusion  780  when the insert is inserted into the punch according to the present invention. The removably fixed interlock between cavity  770  and protrusion  780  removably attaches punch  720  and insert  740 . Therefore, by sliding protrusion  780  of insert  740  into cavity  770  of punch  720 , insert  740  is removably attached to punch  720 . After insertion, insert  740  is fixed onto punch  720 , permitting little or no movement of the insert with respect to the punch. 
   Insert  740  has surface  790  for shaping a sheet of metal. During operation of the press brake, a sheet of metal is placed upon a die. Punch  720  and attached insert  740  are pressed downward such that surface  790  of insert  740  contacts the sheet of metal, pressing the sheet of metal downward and forming the sheet of metal into a desired shape. Generally, the desired shape of the sheet of metal is substantially the shape of surface  790  of insert  740  or of the bending surface of the die. Often, the shape of surface  790  is substantially the same as the shape of the bending surface of the die. In the embodiment of  FIG. 6 , surface  790  is substantially v-shaped, although other shapes may be used. Other shapes contemplated to be within the scope of the invention include, but are not limited to, a substantial u-shape, a substantial channel-shape, a substantial hat-channel shape, a substantial offset-shape, and a substantial flat shape. 
   Surface  790  of insert  740  is at least about as wide along lateral axis  750  as width  760  of punch  720 . This prevents punch  720  from contacting the sheet of metal during operation of the brake press. 
   Persons of skill in the art will appreciate that punch  720  and insert  740  may be made of any material with suitable strength and hardness to withstand the press braking process. Preferably, punch  720  and insert  740  are made of the same material, preferably hardened steel. However, insert  740  may be made of a material different than the material of which punch  720  is made. Many methods and materials may be used to make punch  720  and insert  740 . For example, punch  720  and insert  740  may be comprised of D2 tool steel, heat treated to at least about 50 Rockwell, preferably to between about 55 Rockwell and about 60 Rockwell, then polished and ground. Punch  720  and insert  740  may be coated with a hardening material such as T.D. coating. Such coatings are well known in the art and further assist the punch and inserts in resisting wear and corrosion. 
   Punch  720  may be created as a new product or may be created by machining a worn punch for receipt of insert  740 . 
   Insert  740  may be the same length as punch  720  or may be of a different length. Multiple inserts  740  may be aligned in an end-to-end fashion along the longitudinal axis of the punch to form a longer insert  740 . 
   It will be appreciated by those of skill in the art that the present invention includes alternative embodiments in which the positioning of the protrusion of the insert and the cavity of the punch is reversed. For example, referring now to  FIG. 7 , there is shown another embodiment of the present invention which comprises punch  820  and insert  840 . Punch  820  has longitudinal axis  845  and lateral axis  850 . Punch  820  further has width  860  along lateral axis  850  and protrusion  870  along longitudinal axis  845 . Protrusion  870  has a cross-sectional shape, which, in the embodiment shown in  FIG. 7 , is a substantially dove-tailed cross-sectional shape. 
   Insert  840  has longitudinal axis  875  that corresponds to (is in the same direction as) longitudinal axis  845  of punch  820 . Along longitudinal axis  875 , insert  840  has cavity  880 . Cavity  880  has a cross-sectional shape that matches the cross-sectional shape of protrusion  870  of punch  820 . In the embodiment of  FIG. 7 , the cross-sectional shape of protrusion  870  of punch  820  and of cavity  880  of insert  840  is a substantially dove-tailed cross-sectional shape. However, those of skill in the art will appreciate that other suitable and well-known cross-sectional shapes are contemplated to be within the scope of the invention, so long as the cross-sectional shape permits a removably fixed mechanical interlock between protrusion  870  and cavity  880  when the insert is inserted into the punch according to the present invention. The removably fixed interlock between protrusion  870  and cavity  880  removably attaches punch  820  and insert  840 . Therefore, by sliding cavity  880  of insert  840  onto protrusion  870  of punch  820 , insert  840  is removably attached to punch  820 . After insertion, insert  840  is fixed onto punch  820 , permitting little or no movement of the insert with respect to the punch. 
   Insert  840  has surface  890  for shaping a sheet of metal. During operation of the press brake, a sheet of metal is placed upon a die. Punch  820  and attached insert  840  are pressed downward such that surface  890  of insert  840  contacts the sheet of metal, pressing the sheet of metal downward and forming the sheet of metal into a desired shape. Generally, the desired shape of the sheet of metal is substantially the shape of surface  890  of insert  840  or of the bending surface of the die. Often, the shape of surface  890  is substantially the same as the shape of the bending surface of the die. In the embodiment of  FIG. 7 , surface  890  is substantially u-shaped. However, other suitable shapes are within the scope of the invention, as discussed herein with respect to other embodiments. 
   Surface  890  of insert  840  is at least about as wide along lateral axis  850  as width  860  of punch  820 . This prevents punch  820  from contacting the sheet of metal during operation of the brake press. 
   Referring now to  FIG. 8 , there is shown an embodiment comprising a die  900  and two inserts  910  and  920 . Die  900  has a defined shape  930 , which is substantially u-shaped. Die  900  further has protrusions  940  and  950 , each of which has a cross-sectional shape, namely a substantially T-shaped cross-sectional shape. Insert  910  comprises cavity  960 , which has a cross-sectional shape that matches the cross-sectional shape of protrusion  940 . Insert  920  comprises cavity  970 , which has a cross-sectional shape that matches the cross-sectional shape of protrusion  950 . Insert  910  further comprises surface  980 , which corresponds to a portion of defined shape  930  of die  900 . Insert  920  further comprises surface  990 , which corresponds to a portion of defined shape  930  of die  900 . As such, surface  980  of insert  910 , surface  990  of insert  920 , and defined shape  930  of die  900  combine to form the bending surface against which the sheet of metal is pressed by a punch during operation. 
   Referring now to  FIG. 9 , there is shown an embodiment comprising a die  1000  and two inserts  1010  and  1020 . Die  1000  has a defined shape  1030 , which is substantially hat-channel shaped. Die  1000  further has cavities  1040  and  1050 , each of which has a cross-sectional shape, namely a substantially dove-tailed cross-sectional shape. Insert  1010  comprises protrusion  1060 , which has a cross-sectional shape that matches the cross-sectional shape of cavity  1040 . Insert  1020  comprises protrusion  1070 , which has a cross-sectional shape that matches the cross- sectional shape of cavity  1050 . Insert  1010  further comprises surface  1080 , which corresponds to a portion of defined shape  1030  of die  1000 . Insert  1020  further comprises surface  1090 , which corresponds to a portion of defined shape  1030  of die  1000 . As such, surface  1080  of insert  1010 , surface  1090  of insert  1020 , and defined shape  1030  of die  1000  combine to form the bending surface against which the sheet of metal is pressed by a punch during operation. 
   It will be appreciated by those of skill in the art that the present invention provides tool systems for a press brake that are resistant to wear and that significantly reduce the costs of the press brake process. The inserts of the tool system are positioned on the punch or the die such that the inserts undergo the majority of the wear associated with the press brake process. Consequently, the punch and the die undergo very little wear during use. As a result, the useful life of the punch is dramatically increased, as is the useful life of the die. Because the inserts are much less expensive to make and replace than to make and replace conventional punches or dies, replacing only the inserts produces significant cost savings over a conventional tool system in which the entire punch or the entire die must be replaced every certain number of uses. 
   The present invention can be further modified within the scope and spirit of this disclosure. It will be understood by those of skill in the art that the preferred embodiments disclosed herein describe the present invention in detail, but do not limit or restrict the scope of the invention. The disclosure is intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this disclosure is intended to cover such departures from the disclosed embodiments as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.