This application claims the benefit of German Patent Application No. DE 10 2014 103 927.0 filed Mar. 21, 2014, the contents of which are incorporated herein by reference as if fully rewritten herein.
The invention relates to a drive device for a forming machine. The drive device comprises a hypocyloid gear assembly.
On the output side of the hypocycloid gear assembly, there is an output bearing that can be connected to a ram of a forming machine. Due to the hypocycloid gear assembly, the output drive—and thus a ram fastened thereto—moves linearly in a working direction. For example, a tool of the forming machine may be provided on the ram. Preferably, such a forming machine is disposed for forming blanks of metal, for example round blanks or cups, into hollow cylindrical bodies, for example, can bodies. Such a hollow cylindrical body has a bottom and a cylinder barrel surface.
For example, a drive device comprising a hypocycloid gear assembly for a forming machine has been known from U.S. Pat. No. 6,510,831 B2. The hypocycloid gear assembly comprises an annulus gear with internal toothing. The external toothing of a planetary gear meshes with the internal toothing of the annulus gear. The planetary gear is arranged so as to be rotatable about a planetary gear axis. In a manner radially offset relative to this planetary gear axis, there is a bearing that is connected to a piston rod. Diametrically opposite the bearing, relative to the planetary gear axis, there is provided a counter-weight on the planetary gear. A linear motion of a piston can be converted into a rotary motion via the hypocycloid gear assembly.
Furthermore, U.S. Pat. No. 5,400,635 describes a hypocycloid gear assembly for a forming machine. Therein, a rotating motion of a drive is converted into a linear motion of a push rod. The hypocycloid gear assembly comprises an annulus gear with internal toothing. A planetary gear is supported so as to be rotatable about a planetary gear axis and has external toothing meshing with the annulus gear. The pitch circle diameter of the planetary gear corresponds to the pitch circle radius of the annulus gear. An output bearing supporting a ram is provided on the planetary gear carrier. The planetary gear can be driven via an eccentric gear, said planetary gear rolling in the annulus gear. In doing so, the drive bearing moves linearly.
Considering prior art, the improvement of a drive device comprising a hypocycloid gear assembly for a forming machine should be viewed as the object of the present invention.
An inventive drive device comprises a hypocycloid gear assembly with an annulus gear, a planetary gear system and an eccentric gear. The annulus gear may be provided with internal toothing, for example. The planetary gear system comprises a planetary gear or a orbiting gear that rolls inside the annulus gear and may be provided with corresponding external toothing, for example, said external toothing meshing with the internal toothing of the annulus gear at an engagement location. The pitch circle diameter of the annulus gear is twice the size of the pitch circle diameter of the orbiting gear or the planetary gear of the planetary gear system.
Provided on the planetary gear system is an output bearing. The output bearing is provided at a location on the pitch circle diameter of the orbiting gear or planetary gear of the planetary gear system. A ram of a forming machine is supported by the output bearing, for example; in which case a forming tool may be provided on the forming machine. The output bearing moves linearly along an axis when the orbiting planetary gear or orbiting gear of the planetary gear system orbits in the annulus gear.
Referring to the drive device in accordance with the invention, a first planetary gear equalization mass is provided on the planetary gear system. The first planetary gear equalization mass is located diametrically opposite the output bearing relative to the planetary gear axis. Furthermore, at least one and, optionally, additionally, a second eccentric gear equalization mass is provided on the eccentric gear. The first eccentric gear equalization mass is located diametrically opposite the planetary gear axis relative to the annulus gear axis. The optionally second eccentric equalization mass is preferably provided opposite the first eccentric gear equalization mass relative to the annulus gear axis.
As a result of these equalization masses, it is possible to reduce a resultant force and/or a resultant torque on the annulus gear of the drive device and, in the ideal case, eliminate said force entirely. The equalization masses allow not only the reduction or elimination of a resultant force but, in addition, also the reduction or elimination of the resultant torque. Consequently, not only can the wear of the drive device be minimized but, at the same time, the drive device remains more stable and oscillates less during operation. The use of the drive device in a forming machine can improve the quality of the formed body.
Forming machines frequently operate at high stroke rates. In doing so, stresses are applied to the drive devices due to forces of inertia that contribute to the wear of the drive device. Due to the inventive embodiment of the drive device, the stress due to forces of inertia and thus the wear are reduced.
The positions of the masses described in this application, in particular the equalization masses, correspond to the location of the respective point of gravity of the respective mass. In reality, these masses are not punctiform but may extend radially and/or in peripheral direction relative to the axis of rotation.
It is advantageous if an internal rolling surface for the planetary gear system is provided, where an external rolling surface of the orbiting gear of the planetary gear system is in contact with said internal rolling surface. The orbiting gear may have external toothing on its external rolling surface, and the annulus gear may have internal toothing on its internal rolling surface. In particular, an annulus gear plane extends centrally through the internal rolling surface at a right angle to the annulus gear axis.
In preferred exemplary embodiments, the hypocycloid gear assembly is configured asymmetrically. Hence, there exists no plane of symmetry relative to the hypocycloid gear assembly.
The planetary gear system may comprise, in addition to the orbiting gear, at least one orbiting gear connected to the planetary gear. The at least one planetary gear may be configured to form an integral component with the orbiting gear or be connected to the orbiting gear so as to be engageable or disengageable. The at least one planetary gear is arranged at a distance from the annulus gear plane. The output bearing is arranged on one of the existing planetary gears.
One exemplary embodiment of the drive device comprises a planetary gear system with a first planetary gear and a second planetary gear. The two planetary gears are arranged on opposite sides relative to the eccentric gear and the orbiting gear, respectively. The planetary gear system may be configured so as to be symmetrical to the annulus gear plane or a plane parallel thereto. Preferably, the two planetary gears are located outside an annulus gear plane that is defined by the longitudinal center plane of the internal rolling surface of the annulus gear for an orbiting gear or planetary gear. The output bearing for the ram is arranged on the first planetary gear. The first planetary gear equalization mass is located diametrically opposite the output bearing relative to the planetary gear axis. The first planetary gear equalization mass is provided on the first planetary gear. A second planetary gear equalization mass is provided on the second planetary gear. Also in the case of this arrangement, the resultant forces and torques acting on the annulus gear can be reduced or eliminated.
In a preferred exemplary embodiment, the first planetary gear equalization mass and/or the second planetary gear equalization mass and/or the first eccentric gear equalization mass and/or the second eccentric gear equalization mass are located outside the annulus gear plane. In doing so, the first planetary gear equalization mass may be at a first distance, and/or the first eccentric gear equalization mass may be at a second distance, and/or the second eccentric gear equalization mass may be at a third distance, and/or the second planetary gear equalization mass may be at a fourth distance with respect to the annulus gear plane. Preferably, all the distances are different in dimension. In particular, the dimension of first distance is different from the dimension of the second distance and/or the dimension of the third distance and/or the dimension of the fourth distance. Furthermore, the dimension of the second distance may be different from that of the fourth distance.
The eccentric gear may extend through the annulus gear plane. Preferably, the first eccentric gear equalization mass—viewed with respect to the annulus gear plane—is located on the same side as the first planetary gear equalization mass. In addition, it is advantageous if the first eccentric gear equalization mass and the optionally existing second eccentric gear equalization mass are arranged on opposite sides relative to the annulus gear plane. If a second planetary gear equalization mass is provided in the second drive device, said second equalization mass may be provided on the same side as the second eccentric gear equalization mass, relative to the annulus gear plane.
In one exemplary embodiment of the drive device a bearing equalization mass may be provided in addition to the second planetary gear equalization mass on the optional second planetary gear. The bearing equalization mass is preferably arranged diametrically opposite the second planetary gear equalization mass, relative to the planetary gear axis.
In the second drive device, it is of additional advantage if the position of the bearing equalization mass in peripheral direction about the planetary gear axis corresponds to the position of the output bearing in peripheral direction about the planetary gear axis. Additionally or alternatively, the position of the first planetary gear equalization mass in peripheral direction about the planetary gear axis may correspond to the position of the second planetary gear equalization mass in peripheral direction about the planetary gear axis.
Advantageous embodiments of the invention can be inferred from the dependent patent claims, the description and the drawings. The description describes essential features of the invention with reference to exemplary embodiments. Hereinafter, the invention is explained in detail with the use of exemplary embodiment and with reference to the drawings. They show in
The invention relates to a drive device 10 for a forming machine 11 that is represented by a block circuit diagram in
In order to perform the stroke movement, the push rod 12 is mounted to a rod 15. The ram 15 extends along the axis A. This rod may be supported at one or several locations so as to be movable back and forth along the axis A via a bearing arrangement.
Associated with the drive device 10 is a hypocycloid gear assembly 20 that is driven at a drive input 21 by a driving motor 22, for example an electric motor. The drive input 21 is provided on an eccentric gear 23. The hypocycloid gear assembly 20 is further associated with an annulus gear 24 that is provided with internal toothing 24a, said toothing representing an internal rolling surface of the annulus gear 24. The internal toothing 24a is arranged coaxially about an annulus gear axis HA. The annulus gear 24 is arranged so as to be immovable relative to a machine frame 25 of the forming machine 11.
A planetary gear system 28 of the hypocycloid gear assembly 20 comprises an orbiting gear 29. The orbiting gear 29 has an external rolling surface formed by external toothing 29a. The external toothing 29a meshes with the internal toothing 24a of the annulus gear 24 at the engagement site. The planetary gear system 28 is connected to the eccentric gear 23 in a driving manner. In one drive of the driving motor 22, the eccentric gear 23 moves the orbiting gear 29 in such a manner that said orbiting gear rolls inside the annulus gear 24. In doing so, the planetary gear system 28 is supported so as to be appropriately rotatable relative to the eccentric gear 23.
An output bearing 30 is arranged on the planetary gear system 28, in which case the planetary gear system 28 thus represents a gearing output 31. The ram 15 is supported by the output bearing 30.
In the hypocycloid gear assembly 20, the output bearing 30 is arranged on the pitch circle TU of the orbiting gear 29. During operation of the drive device 10, the pitch circle TU of the orbiting gear 29 rolls in the pitch circle TH of the annulus gear 24, as is schematically illustrated by
The output bearing 30 is arranged on the first planetary gear 35, where the ram 15 and the push rod 12 are located. This results in a first mass m1 that is to be driven. The maximum first radial distance r1 of the first mass m1 of the annulus gear axis HA is shown in
Arranged on the eccentric gear 23 is a first eccentric gear equalization mass m3. This first eccentric gear equalization mass m3 is arranged—relative to the annulus gear plane HE—on the same side as the first planetary gear equalization mass m2. On the opposite side of the annulus gear plane HE—relative to the annulus gear axis HA and diametrically opposite the first eccentric gear equalization mass m3—there is arranged a second eccentric gear equalization mass m4 on the eccentric gear 23. The second eccentric gear equalization mass m3 is located opposite the annulus gear axis HA, diametrically opposite the planetary gear axis PA.
Due to the various masses, a force is generated on the respective annulus gear 24: The first mass m1 generates a first force F1, the first planetary gear equalization mass m2 generates a second force F2, the first eccentric gear equalization mass m3 generates a third force F3, the second eccentric gear equalization mass m4 generates a fourth force F4, and the first planetary gear 35 generates a planetary gear force FP1. In doing so, the following relationships apply:
F
1
=m
1
·r
1·ω2·cos(ωt) (1)
F
2
=m
2
·r
1·ω2·sin(ωt) (2)
wherein (1) and (2) with m12=m1=m2 result in:
F
12
=m
12
·r
1·ω2 (3)
F
3
=m
3
·r
1·ω2 (4)
F
P1
=m
P1
·r
2·ω2 (5)
wherein mP1 is the mass of the first planetary gear 35.
In order for the forces acting on the annulus gear 24 to equalize, the following must be satisfied:
Equation (6) then results in:
Using equation (8) as well as the equalization of the forces on the annulus gear 24, it is possible to determine the equalization masses, so that, during the operation of the drive device 10 and the first hypocycloid gear assembly 20a, respectively, the resultant force, as well as the resultant torque, on the annulus gear 24 can be eliminated in the ideal case or at least reduced.
In the exemplary embodiment of the second hypocycloid gear assembly 20b described here, it is possible to omit the second eccentric gear equalization mass m4. Likewise, in the first hypocycloid gear assembly 20a, it is possible—in a modified embodiment—to optionally omit the second eccentric gear equalization mass m4.
Analogous to the description of the first exemplary embodiment, a fifth force F5 results from the second planetary gear equalization mass M5 and a sixth force F6 from the bearing equalization mass m6, as follows:
F
5
=m
5
·r
1·ω2·sin(ωt) (9)
F
6
=m
6
·r
1·ω2·cos(ωt) (10)
Due to the mass mP2 of the second planetary gear 36, there results a second planetary gear force FP2, namely:
F
P2
=m
P2
·r
2·ω2 (11)
The fifth force F5 and the sixth force F6 can be used analogously to equations (1) to (3) where m56=m5=m6 to determine the following equation:
F
56
=m
56
·r
1·ω2 (12)
The distances in axial direction (x-direction) from the annulus gear plane HE of the masses or the points of contact of the forces of the exemplary embodiment of
Corresponding to the first hypocycloid gear assembly 20a, it is also possible to provide an at least partial force equalization and torque equalization for the second hypocycloid gear assembly 20b. Based thereon, it is possible to then determine the individual masses in order to optimize the second hypocycloid gear assembly 20b such that the lowest possible resultant forces and torques act on the annulus gear 24.
The invention relates to a drive device 10 for a forming machine 11. The drive device 10 comprises a hypocycloid gear assembly 20. The hypocycloid gear assembly 20 comprises an eccentric gear 23, a stationary annulus gear 24 and a planetary gear system 28. The planetary gear system 28 includes an orbiting gear 29 orbiting and rolling in an annulus gear 24. The orbiting gear 29 is connected to at least one first planetary gear 35 of the planetary gear system 28. Alternatively, a planetary gear 35, 36 each may be arranged on opposite sides of the orbiting gear 29. On the first planetary gear 35, there is provided a first planetary gear equalization mass m2 diametrically opposite an output bearing. At least one first eccentric gear equalization mass m3 and, optionally, a second eccentric gear equalization mass m4, are arranged on the eccentric gear 23. The first eccentric gear equalization mass m3 is arranged diametrically opposite, relative to a planetary gear axis PA about which the planetary gear system 28 rotates. The resultant forces and torques acting on the annulus gear 24 can at least be reduced by the equalization masses.
Number | Date | Country | Kind |
---|---|---|---|
102014103927.0 | Mar 2014 | DE | national |