The present invention relates to machine tools and, more particularly, to devices for performing machining operations on a moving web of metal or similar material.
For maximizing manufacturing throughput on an industrial scale, metal sheets are oftentimes processed as a moving web of material. Thus, an elongate sheet of metal is driven past a series of manufacturing stations, typically on a conveyor or similar moving support, where various machining or other operations are carried out on the moving web. One such operation involves applying a die set to the metal web, for deforming the web in a desired manner. For example, the die set may include a punch and a die, which, when pressed together with the web in between, form a hole in the web.
For carrying out punching operations on a moving web of metal, one or more punches are typically attached to the surface of a rotating drum or wheel, which is deployed on one side of the metal web. The other side of the metal web is supported in a complementary manner, e.g., a die or other support surface. The drum is carefully speed matched to the speed of the web. As the drum rotates, the punches on the surface of the drum are rotated into punching contact with the moving web, forming a hole or other desired feature. However, because the drum moves in a rotating manner whereas the web is moving linearly, there is a non-ideal interaction between the punch and web. In particular, not only does the punch move in a vertical direction with respect to the web, as in an ideal punching operation, but there is a concomitant degree of relative lateral motion as well. This “sweeping” or “wiping” motion of the punch causes the edges of the punch to laterally interact with the web, which can damage the punch or at least severely limit the times between required changeover or retooling.
It is an object of the present invention to provide a rotary punch that mimics, in an ongoing and continuous basis, an ideal punching operation (or other die-based machining operation) on a moving web of metal or other material.
To achieve this and other objects, an embodiment of the present invention relates to a rotary punch having a support frame, an upper die plate assembly, and a lower die plate. (In this context, “rotary punch” refers to a machine tool using a die set for carrying out a periodic or repeating machining operation on a web of material, including, but not limited to, punching operations.) The support frame includes a drive assembly, which rotates or drives the upper die plate assembly both horizontally and vertically along a generally circular pathway. The lower die plate is connected to the support frame for movement in a linear horizontal direction only, that is, the lower die plate is limited to moving horizontally back-and-forth. The upper die plate assembly is slidably connected to the lower die plate, e.g., by way of one or more vertical alignment rods that extend through bushings provided in the lower die plate. Thus, in operation, as the upper die plate assembly is moved horizontally and vertically along its circular pathway, the lower die plate horizontally follows or tracks along with the upper die plate assembly, as the upper die plate concurrently moves towards and away from the lower die pate. This maintains a substantially constant alignment between the lower die plate and the upper die plate assembly for carrying out a periodic machining operation on a moving web of material passing between the upper die plate assembly and the lower die plate. (By “substantially” constant, it is meant constant but for variances originating from manufacturing tolerances.)
In another embodiment, when the upper die plate assembly is driven to move horizontally at a speed that matches the speed of the moving web of material (with the lower die plate following along), that is, the horizontal component of the upper die plate assembly's movement matches the speed of the moving web, there is substantially no relative horizontal movement between the upper die plate assembly, the lower die plate, and the moving web of material, during at least part of the time when the upper die plate assembly is moved vertically towards the lower die plate for carrying out the machining operation on the moving web of material. In this manner, the upper die plate assembly and lower die plate are speed matched to the moving web, while concurrently moving toward one another (relatively speaking), for performing the punching operation or other machining operation. This mimics, or at least substantially approximates, an ideal machining operation on a web of material, where there is no unwanted relative lateral movement between the die plates and web of material.
In another embodiment, the upper die plate assembly includes two parallel, vertically oriented side plates (each carrying a cylindrical bearing), one or more vertical alignment rods attached to the top of each of the side plates, and an upper die plate attached to the top ends of the alignment rods. The upper die plate assembly is slidably connected to the lower die plate. In particular, the alignment rods extend vertically through bushings provided in the lower die plate, for the upper die plate assembly to slide vertically towards and away from the lower die plate. The lower die plate is carried on opposed linear bearing and rail assemblies attached to the support frame, and is positioned between the upper die plate and the side plates of the upper die plate assembly. The drive assembly is a crankshaft having two aligned, offset journals. The journals are connected to the cylindrical bearings of the upper die plate assembly side plates. Thus, when the crankshaft is rotated about its axis, the offset journals move about a circular orbit, which in turn causes the upper die plate assembly side plates, and thus the entirety of the upper die plate assembly, to move along the generally circular pathway. (As should be appreciated, because the upper die plate assembly is slidably connected to the lower die plate, which cannot move vertically, the upper die plate assembly is maintained at a substantially constant attitude as it moves along its circular pathway.)
In another embodiment, for carrying out a machining operation, the rotary punch includes a die connected to the top surface of the lower die plate, and a work member, complementary to the die, connected to the bottom surface of the upper die plate. For example, the work member may be a punch for generating a hole in the moving web of material. In such a case, the lower die plate may include a drop aperture cooperative with the die and punch for removing waste material.
In another embodiment, the rotary punch includes two gusset plates, which are attached to the underside of the lower die plate and extend downwards there from. A bottom support or stiffening plate is attached to the lower ends of the gusset plates. The alignment rods of the upper die plate assembly are slidably connected to the bottom stiffening plate, similarly as with the lower die plate. The gusset plates and bottom stiffening plate form a box section in conjunction with the lower die plate, which stiffens the lower die plate and helps to stabilize the moving portions of the rotary punch.
The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:
With reference to
When the upper die plate assembly 24 is driven so that the speed its horizontal component of movement matches the speed of the moving web of material 34 (with the lower die plate 28 following along), there is substantially no relative horizontal movement between the upper die plate 26, the lower die plate 28, and the moving web of material 34, at least during part of the time when the upper die plate assembly is moved vertically towards the lower die plate for carrying out the machining operation on the moving web of material 34. In this manner, the upper die plate assembly 24 and lower die plate 28 are speed matched to the moving web 34, while concurrently moving toward one another in a relative sense, for performing a punching operation or other machining operation. This mimics (or at least substantially approximates) an ideal machining operation on a web of material, where there is no unwanted relative lateral movement between the die plates and web of material.
As indicated above, although the present invention is characterized as being a “rotary punch,” this is meant to refer more generally to a machine tool that uses a die set for carrying out a periodic or repeating machining operation on a web of material. One possible machining operation, of course, is a true punching operation, for removing material from the web to form apertures therein. “Rotary” refers to the rotation of the drive assembly axle or crankshaft, and also to the machine tool working in a cyclical manner, for repeating the machining operation on a moving web of material.
With reference to
The plates 38a, 38b, 40a, 40b, like most of the plate components of the rotary punch 20 described herein, are generally planar, and are made out a very heavy gauge (e.g., 0.5″-2″ thick) sheet steel or other strong and sturdy metal. This facilitates use of the rotary punch 20 for performing machining operations on metal webs. If the punch 20 is meant to be used for machining operations on light gauge materials such as very thin, malleable, or soft metals, or on certain plastics, then it may be possible for the punch plates and other components to be lighter duty in nature.
The drive assembly 30 is carried on the support frame 22, and includes an axle or crankshaft 42 and two aligned, offset circular journals 44a, 44b. The crankshaft 42, lying parallel to the base 36, extends between and is supported by the left and right support frame plates 38a, 38b. The crankshaft 42 is attached to the left and right support frame plates 38a, 38b by way of two support bearings 46a, 46b that are disposed in the left and right support frame plates 38a, 38b, respectively. As such, the crankshaft 42 is free to rotate about its fixed longitudinal axis “L” (see
A standard motor unit 48 may be used to drive the crankshaft 42. The motor unit 48 includes a servo motor 50, a gearbox or reducer 52 (if required for the type of motor used), and a motor unit output spindle or similar connection means 54 for connecting the rotating output of the motor unit 48 to the crankshaft 42. Other types of crankshaft drive units are possible for rotating the crankshaft, such as internal combustion engines, pulley systems, and the like.
The lower die plate 28 is disposed between the left and right support frame plates 38a, 38b, and is connected thereto for moving in a linear horizontal direction “A.” (Typically, the linear horizontal direction “A” corresponds to the direction of travel of the moving web of material 34.) For this purpose, first and second linear bearing and rail assemblies 56a, 56b are respectively attached to the top edges of the left and rights support frame plates 38a, 38b. The linear bearing and rail assemblies 56a, 56b allow the lower die plate 28 to move back-and-forth in the direction “A,” but otherwise prevent the lower die plate from moving. In particular, the lower die plate is vertically fixed, meaning that it is prevented from moving vertically up or down, or from twisting or angling out of the horizontal. (In the context of the lower die plate, the designation “horizontal” or “lateral” refers to a plane defined by the lower die plate, or a plane parallel to that plane, not necessarily to a plane that lies horizontal to the ground. “Vertical” refers to a direction perpendicular to the plane defined by the lower die plate.)
In the embodiment shown in the drawings, the lower die plate 28 is generally H-shaped, with the legs of the “H” shape being defined by two side clearance cutouts 58a, 58b. The cutouts 58a, 58b accommodate the passage of two vertical reinforcement braces 60a, 60b, which are part of the upper die plate assembly 24, as discussed in more detail below. The lower die plate 28 also includes fixtures 62 for attaching the die portion 64 of a die set (which includes the die 64 and a punch or other work member 66) to the top surface of the lower die plate 28. If the machining operation carried out by the rotary punch 20 involves the removal of material from the web of material 34, then the lower die plate 28 will also typically include a drop aperture 68 for facilitating the passage of waste material 70 (see
The upper die plate assembly 24 includes two parallel, vertically oriented side plates 72a, 72b, two vertical alignment rods 74 attached to the top edge of each of the side plates 72a, 72b (there are four rods 74 in total), the vertical reinforcement braces 60a, 60b, and the upper die plate 26, which is attached to the top ends of the alignment rods 74 and vertical reinforcement braces 60a, 60b. The upper die plate 26 is generally I-shaped, and lies generally parallel to the lower die plate 28. Like the lower die plate, the upper die plate includes standard fixtures (not shown) for attaching a punch or other die set work member 66 to the underside of the upper die plate. The side plates 72a, 72b are positioned proximate (and generally parallel) to the left and right support frame plates 38a, 38b, respectively. As best shown in
In total, the upper die plate assembly 24 includes the side plates 72a, 72b, the upper die plate 26, and the alignment rods 74 and vertical reinforcement braces 60a, 60b, which connect the side plates and upper die plate together. These components are non-movably attached to one another, thereby forming a stiffened, generally Π- or U-shaped unitary body that moves together as a unit.
Each upper die plate assembly side plate 72a, 72b is outfitted with a cylindrical bearing 86, which is located in a corresponding bearing aperture 88 formed in the side plate. In turn, the offset journals 44a, 44b of the drive assembly 30 are respectively positioned in the bearings 86, in a laterally fixed manner so that the journals do not become misaligned or disengaged from the bearings. The cylindrical bearings 86 allow the side plates 72a, 72b to rotate with respect to the journals, in a low-friction manner. Additionally, the drive assembly 30 (which includes the crankshaft and journals) supports the upper die plate assembly 24 in the support frame 22. The upper die plate assembly rests on the journals and crankshaft, with the crankshaft in turn being supported by the left and right support frame plates 38a, 38b.
The vertical alignment rods 74 of the upper die plate assembly 24 extend through the lower die plate 28, and are vertically slidable with respect thereto. For this purpose, the lower die plate 28 is provided with vertically oriented rod apertures 90 and bushings 92 that accommodate the alignment rods 74 in a sliding, low-friction manner. This enables the upper die plate assembly 24 to move vertically towards and away from the lower die plate 28, while remaining aligned therewith at a substantially constant attitude. The vertical reinforcement braces 60a, 60b also extend through the plane of the lower die plate and move vertically with respect thereto, but merely pass through the side cutouts 58a, 58b in the lower die plate, without contacting the lower die plate, as opposed to engaging the lower die plate in a sliding manner through use of bushings or otherwise.
Optionally, the rotary punch 20 also includes a means for stiffening and reinforcing the lower die plate 28. As best shown in
The gusset plates 94 and bottom stiffening plate 96 are attached to the lower die plate 28 in a standard manner, using machine bolts 98 or the like, as shown in
Operation of the rotary punch is shown schematically in
Because the upper die plate assembly is slidably connected to the lower die plate 28 (by way of the rods 74), as the upper die plate assembly 24 is moved vertically and horizontally along the circular path 32, the lower die plate 28 moves along with the the upper die plate assembly horizontally back and forth. (As explained above, the lower die plate is limited to this direction of movement by the linear bearing and rail assemblies 56a, 56b.) At the same time, the sliding connection between the upper die plate assembly and lower die plate serves to synchronize the two plates. More specifically, a substantially constant alignment is maintained between the upper and lower die plates as the upper die plate moves vertically, e.g., the upper die plate is maintained at a substantially constant attitude with respect to the lower die plate. When the upper die plate 26 is fully raised, as shown in
In the case of a die set, machining operations are carried out by forcing the work member portion 66 of the die set against (or towards) the die portion 64 of the die set, with a metal sheet or other material web lying between the two. Thus, in the rotary punch 20, the machining operation is carried out when the upper die plate 26 (which carries the punch or other work member 66) transitions from its initial half stroke (
The primary purpose of the rotary punch is to perform punching or other machining operations on a moving web of metal 34 or other material. For doing so, the upper and lower die plates 26, 28, which are synchronized in terms of horizontal position and attitude, are speed matched to the speed of the moving web of material. Thus, with reference to
The upper and lower die plates are speed matched to the moving web of material using a standard control mechanism. The horizontal speed of the plates is a direct function of the rotational speed of the crankshaft, which is driven by the motor unit. The control mechanism monitors the speed of the web, and controls the motor to produce a corresponding speed in the upper and lower die plates, based on a simple mathematical calculation, reference to a lookup table, or the like.
Although the die plates have been characterized as an “upper” and “lower” die plate, these are arbitrary designations. For example, as shown in
Although the upper die plate assembly has been illustrated as including vertical reinforcement braces 60a, 60b, these components are optional, and could either be omitted or replaced with additional alignment rods 74, if the degree of stiffness and other mechanical properties of the upper die plate assembly remained suitable for the machining task to be carried out using the rotary punch.
As noted above, the term “substantially” as used herein refers to the element in question exhibiting the stated characteristic, but for variances arising from manufacturing tolerances.
Although the upper and lower die plates have been illustrated as being H- or I-shaped, the die plates could be shaped or configured otherwise without departing from the spirit and scope of the invention. For example, the lower die plate could be rectangular if vertical reinforcement braces 60a, 60b are not used as part of the upper die plate assembly 24. The upper die plate could also be rectangular.
As shown in
Since certain changes may be made in the above-described rotary punch, without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.
This application claims the benefit of U.S. Provisional Application Ser. No. 60/864,888, filed Nov. 8, 2006, incorporated by reference herein in its entirety.
Number | Date | Country | |
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60864888 | Nov 2006 | US |