Device connected to a crank for moving a part mounted on a slider relative thereto

Abstract

A device on a slider crank for generating a motion relative to the a slider (press ram 5) of a part (ejecting spring pin 6) mounted on the slider, wherein such motion is taken off a crankpin (1) upon rotation of the crankpin around a crankshaft axis and transmitted along a pushrod (connecting rod 4) to the part (ejector spring pin 6). For this purpose, revolving parts (wheel 22, 34, 38; disk 98, 100, belt 102; disk 142, 148, belt 150) transmit rotary motion on the connecting rod (26, 28; 144) (FIG. 1).

Description

The invention concerns a device on a slider crank for the purpose of generating a motion relative to the slider of a part supported on the slider, in accordance with the introductory part of the patent claim 1 defining the type.

For powering an ejector pin on the die of a forming press, it has been a familiar technique for quite some time to introduce, from the outside, a motion into the slide that is reciprocal to the return travel of the press slide in order to eject the workpiece from the pressing die, such as hexagonal head dies, by means of an ejector pin. Due to the many components between the point of introduction of the force and the ejector, such systems are very elastic. In addition, they also usually involve reciprocating movements.

The device known from DE 195 21 041 A1 has the purpose of reducing this mechanical complexity. This device serves for controlling auxiliary devices such as die ejector pins, strippers, or die carriers in an oscillating press ram of single and multi-stage presses. This is accomplished by a cam attached to the crankpin of the crankshaft of a forming press that controls a pushrod sliding inside the connecting rod; via a spring pin, the motion of this pushrod is transferred to the die, causing the tip of the spring pin to eject the workpiece from the die. When the crank performs one revolution, the cam also performs one revolution in relation to the pushrod. The point of contact between the pushrod and the spring pin is in the center of rotation of the bearing pin connecting the connecting rod with the press ram.

In this DE 195 21 041 A1, an oscillating motion is introduced into the slide.

This invention now addresses the problem of eliminating the disadvantages described above by producing a rotary motion.

Starting with a device of the type referred to at the beginning, the invention solves this problem with the characteristic features of claim 1.

Due to the fact that the rotary motion is transmitted from the crankshaft along the pushrod of the slider crank into the press slide, and that the operating motion is derived directly from this press slide, the invention can be applied universally and makes it possible to transmit large transmission forces in a direct power flow to the operating motion required in each case. Since, except for the tool movement, no additional sliding motions but only rotary motions are involved in transmitting the motion, the device proposed by the invention operates with extremely little wear.

All motions can be produced that can be derived from a rotary motion via appropriate gears.

To be sure, DE 34 12 147 A 1 refers to a centric slider crank, with a transmission that also consists of rotating parts (intermediate gear wheel 24, gear wheel 25), but with one gear wheel (25) fixed on a crank pin (16) that rotates in a crank disk (12) with a centric drive shaft (13); however, part of this transmission is a stationary gear wheel (18) that is coaxial in relation to the shaft axis, and also a rotating gear wheel (23) supported on the crank disk (12) that is located between the stationary gear wheel (18) and the rotating gear wheel (25), and meshes with both of them.

That means that a rotary motion of the crank disk (12) causes a rotary motion of the crank arm (15) relative to the rotated crank disk (12), with said motion depending not only on the crank radius but also on the gear ratio (e.g. 2:1) of the stationary gear wheel (18) and the rotating gear wheel (25). Moreover, this familiar type of transmission does not extend, via the crank arm 15, to the slide (4), so that the generation of a motion—relative to the slide—of a part (such as the slide bar 28) supported on the slide (slider) was not part of the considerations at all.

This is also true for DE-GM 1 864 599 (FIGS. 3 and 4) where, in order to produce two superimposed motions of the pushrod (pushrod 9), on the crank side this pushrod is supported by means of an additional cam (8) on a gear wheel (6) on the main cam (crank pin 5), with the gear wheel (6) meshing with a centrically stationary gear wheel (7).

The invention is explained in detail on the following pages with the help of the six design variants shown in schematic form by the drawings.

FIG. 1 shows a front view of a first design variant for controlling the ejector pin of a forming press.

FIG. 2 shows a top view of the design variant in FIG. 1 as a partial view.

FIG. 3 shows a front view of a second design variant for controlling the ejector pin.

FIG. 4 shows a front view of a third design variant for controlling the ejector pin.

FIG. 5 shows a front view of a fourth design variant for controlling an additional operating motion that is merely indicated.

FIG. 6 shows a front view of a fifth design variant for controlling a wire clamping device, as used, for example, in the feeder slide of a wire processing machine.

FIG. 7 shows a front view of a sixth design variant for controlling the press slide of a forming press when a stop/pause is specified for its front reversing position.

FIG. 8 shows a top view of the design variant in FIG. 7 as a partial view.

FIG. 9 shows a time-traverse diagram to illustrate the progress of the slide movement in relation to the angle of rotation of the crankshaft.

FIGS. 10 and 11 each shows an additional time-traverse diagram to illustrate the progress of the slide movement with altered starting conditions.

FIGS. 1 and 2 show the first design variant of the device proposed by the invention. It serves as the driver for an ejector pin 62 on the die side that is integrated in the crank gear of a single or multiple stage press. Here, a press slide 12 that slides back and forth in a guide has the purpose of producing, by means of slide-mounted forming tools and stationary dies, finished workpieces such as screws, bolts, etc. from blanks in multiple steps.

The press slide 12 is driven by a crankshaft 14 supported by a main crankshaft bearing that is not shown. Via an eccentric crankpin 20, the crankshaft 14 drives two connecting rods 26, 28 that act on a bolt 18 supported in the slide 12. On the crankpin 20 of the crankshaft 14, a stationary drive gear wheel 22 is mounted that rotates in opposition to the connecting rods 26, 28.

In FIG. 2, the connecting rod 26 is located above the drive gear wheel 22. The other connecting rod 28 is located below the gear wheel 22, separated by a spacer bushing 30. The drive gear wheel 22 meshes with an intermediate gear wheel 34 that rotates freely on a pin 36 that is mounted in the connecting rods 26, 28. The intermediate gear wheel 34 meshes with a driving gear wheel 38 that is mounted on a pin 18 at that end of the connecting rods 26, 28 that is opposite of the crankpin 20.

A cam 44 is connected in fixed position to the gear wheel 38 that freely rotates on the pin 18. For the purpose of transmitting a stroke movement, the cam 44 rotating in the press slide 12 acts on a cam roller 48 rotating on a pin 48 that is attached to the lower end of a roller lever 50. The other end of the roller lever 50 pivots on a pin 54 that is mounted in a roller lever bearing 56 on the press slide. With its lateral surface 58, the lower end of the roller lever 50 contacts the ejector pin 62. The ejector pin 62 is driven in an oscillating fashion by the roller lever 50. The ejector pin 62 is supported in a rear bearing bushing 64 and a front bearing bushing 66, with the bearing bushing 66 forming the back rest for a coil spring 68. The force of the coil spring 68 presses the ejector pin 62 and the cam roller 46 against the control cam 44.

FIG. 3 shows a second, modified design variant of the device proposed by the invention for driving the ejector pin 62 of a forming press that is located on the die side. Here, the driving gear wheel 38 meshes with a driven gear wheel 72 that rotates on a pin 74 above the gear wheel 38, with the pin 74 mounted in a bearing 76 on the press slide 12. In this variant, the cam 44 attached to the driving gear wheel 38 in FIGS. 1 and 2 has been replaced by a cam 44′ that is now firmly attached to the driven gear wheel 72. The cam disk 44′ acts on a cam roller 82 rotating on a pin 84 that is mounted on an arm 88 of a two-arm roller lever 90. The roller lever 90 itself pivots on a pin 92 on the press slide 12. In order to perform the ejection motion, the free end of the lever 90 acts on an ejector pin 62′ whose design and function is identical to that in the first design variant.

In the design variant shown in FIG. 4, the gear drive 22, 34, 36 of the first and second variant has been replaced by a toothed belt drive 96. Here, instead of the driving gear wheel 22, a toothed driving disk 96 is mounted in fixed position on the crankpin 20 of the crankshaft 14. In alignment with this toothed disk 96, a driven toothed disk 100 rotates on pin 18. A toothed belt 102 connects both toothed disks 98 and 100.

Next to the driven toothed disk 100, a driven gear wheel 106 rotates on the pin 18. The driven gear wheel 106 is attached in fixed position to the driven toothed disk 100, performing the same rotations as the toothed disk 100. Here, the driven gear wheel 106 and the driven toothed disk 100 both have approximately the same exterior diameter. Thus, their outlines coincide in FIG. 4. The driven gear wheel 106 meshes with the gear wheel 72 mounted on the press slide 12, and in terms of location and function, the gear wheel 72 as well as the other components 44′, 82 to 92, and 62′ to 68 correspond to the device shown in FIG. 3.

Of course, instead of the toothed disks 98 and 100 and the toothed belt 102, it is also possible to use a chain drive consisting of a set of chain sprocket wheels and a chain.

In the fourth variant shown in FIG. 5, the driven gear wheel 72 is firmly connected with a driving bevel gear 110 that drives a driven bevel gear 112. The driven bevel gear 112 is fixed in position on a shaft 114 that rotates in a bearing block 116 sitting on the press slide 12.

FIG. 6 shows the fifth design variant of the invention. It serves to clamp wire or strip-shaped material 122 with a slide 124, as used, for example, as a feeder slide of a wire or strip processing machine. This requires an adjustable feeder stroke. In a previously known fashion, the stroke adjustment is achieved by a drive crank 128 that has a T-groove block 130 which, after loosening the nut 138, is adjusted in a T-groove block guide 132 by means of an adjusting screw 136 either away from the center of the drive crank 128 or towards it. The T-groove block 130 is pin-shaped, and, according to FIG. 4, an driving toothed disk 142 is mounted in fixed position on its round section 134 representing the crankpin. In addition, a connecting rod 144 is supported on the round section of the T-groove block 130, and the opposite end of this connecting rod is linked to the slide 124 by means of the pin 146. A driven toothed disk 148 rotates on the pin 146. A toothed belt 150 connects both toothed disks 142 and 148. A cam disk 152 is mounted in fixed position on the driven toothed disk 148, and this cam disk actuates a roller cam 158 rotating on a roller lever 156. A clamping jaw 162 is connected with the roller lever 156; it clamps the wire or strip 122 to be fed against the counter jaw 164 during the feeding motion of the slide 124, resulting in a wire feed. The clamping force required for this is exerted on the wire 122 via a spring holder 186 attached to the slide 124 by a compression spring 168 that acts on the wire via the roller lever 156. The shape of the cam disk 152 is designed so that the wire 122 is released from the movable clamping jaw 162 during the return motion of the slide.

In all design variants shown here, the gear ratios may be selected as desired.

The sixth design variant of the device proposed by the invention, as shown in FIGS. 7 and 8, can be used if the forming or multistage press operates with a relatively high cyclic rate and a safe and precise workpiece delivery after the ejection action of the ejector pin as well as the safe pick-up of the workpieces at the tools, or at the tools of the individual stations is required.

For purposes of an automatic transfer of the workpieces on a progressive forming press or multistage press, the workpieces are picked up after their ejection at one workstation in familiar fashion by the paired gripper fingers of a transfer device, as known from DE 40 02 347 A1, for example, and are then transferred to another workstation for further processing.

Because these pick-up or transfer processes as well as the back and forth movement of the transfer device between the pick-up and drop-off position are time-consuming, the invention provided for a certain pause of a press slide 12′ after its advance and prior to its return travel, as described below.

For this purpose, according to FIGS. 7 and 8, a driving gear wheel 22′ mounted in a fixed position on the crankpin 20′ of the crankshaft 14′ drives a driven gear wheel 38′ directly, without an intermediate gear wheel. The driven gear wheel 38′ is mounted in a fixed position on an eccentric pin 174 supported in the press slide 12′. Specifically, the driven gear wheel 38′ sits on a centric center section 176 of the eccentric pin 174. The centric center section 176 of the eccentric pin 174 protruding from both sides of the driven gear wheel 38′ engages appropriate holes in two connecting rods 26′, 28′, thus supporting the driven gear wheel 38′ in these connecting rods 26′ and 28′. The driving gear wheel 22′ and the driven gear wheel 38′ operate like a normal spur-wheel gear between the connecting rods 26′, 28′. The eccentric sections 178 of the eccentric pin 174 on both sides of the centric center section each engage appropriate holes serving as supports for the eccentric pin 174 in the press slide 12′.

When the crankshaft 14′ rotates, the driven gear wheel 38′ moves the press slide 12′, now driven by the eccentric section 178 of the pin 174 like an additional crank gear with a certain stroke, in addition to the slide travel imparted on the press slide 12′ by the connecting rods 26′ and 28′. Here, the ends of the connecting rods 26′, 28′ perform a circular relative motion around the bearing 180 of the eccentric sections 178 in the press slide 12′.

FIG. 9 through 11 show the slide movements rendered as curves in a time-traverse diagram. The dotted line 190 represents the movement of the press slide 12′ resulting from the rotation of the crankshaft 14′, and the dash-and-dot line 192 represents the additional movement of the press slide 12′ generated by the eccentric section 178 of the eccentric pin 174. The third, solid line 194 shown in the diagrams is the mechanical addition of the two generated oscillations (curves 190, 192) resulting from the two motions imparted on the press slide 12′.

Because of this addition, the two actual and quasi-sine-shaped oscillations result in slide movements with selectable pauses, or in a double stroke, depending on the starting condition.

For example, one starting condition is the shifting of the two sine oscillations on the abscissa of the diagrams (shift angle α in relation to the angle of rotation of the crankshaft 14′), or the gear ratio i of the driving gear wheel 22′ and the driven gear wheel 38′.

In the design variants according to FIG. 9 to 11, a fast gear ratio of i=2 was selected so that the eccentric section 178 of the pin 178 generates a double sine oscillation relative to the crankshaft sine oscillation.

In FIG. 9, both sine oscillations 190 and 192 start simultaneously, i.e. the shift angle α is zero degrees with a gear ratio of 2. In this case, there is a double stroke of the press slide 12′ in the points 196 and 198, as a maximum slide stroke. Between the two points 196 and 198, the press slide 12′ returns to a minimum value, so that, for all practical purposes, the press slide 12′ pauses between the two points 196 and 198.

By shifting the sine oscillations by a relative angle of α=300, the double stroke in FIG. 9 can be turned into a deceleration of the press slide 12′ motion prior to the actual pressing process, from point 206 to point 208 in FIG. 11, before the press slide 12′ fully reaches its front stop at point 210.

For performing the motion of the ejector pin 62 or 62′, a cam disk 44″ (FIG. 8) is connected in a fixed position with the driven gear wheel 38′ via the center section 176 of the eccentric pin 174, driving one of the ejector pins 62 (FIG. 2) or 62′ (FIGS. 3 and 4).

In all design variants, the curve of the cam disk 44″ is adapted to the superimposed curve of the motion 194 of the press slide 12′ so that the workpieces can be ejected with precision and at the exact time and can be picked up by the gripper fingers (not shown) of the transfer device.

A gear ratio of i=3 or more may also be selected, and the result will be a triple or multiple sine oscillation that is superimposed on the main motion from the crankshaft 14′, i.e. is added to it mechanically.

In a variant of the sixth design variant, the centric center section 176 of the eccentric pin 154 extends into, and even beyond the two appropriately shaped halves of the bearing 180 in the press slide 12′ which used to accept the two separate halves of the eccentric section 178. In that case, the two eccentric section halves are located in the two protruding sections of the eccentric pin 174 on both sides of the press slide 12′. They act jointly with freely rotating rolls or similar devices supported on both exterior surfaces of the slide to produce the back and forth movement of the slide 12′.

Claims

1. A slider crank mechanism comprising a reciprocating slide (12, 124), a crank (14, 128), a connecting rod (26, 28, 144) connected at a first end by a crank pin (20, 138) to the crank and at a second end by a hinge pin (18, 146) to the slide such that rotation of the crank effects reciprocating movement of the slide, a driving rotating member (22, 98, 142) and a driven rotating member (38, 100, 148) respectively located on the crank pin and hinge pin at the first and second ends of the connecting rod with rotation axes thereof respectively aligned coaxially with center axes of the crank pin and hinge pin, at least one rotary motion transfer member (34, 102, 150) connecting the driving rotating member to the driven rotating member for transmitting rotary motion of the driving rotating member to the driven rotating member along the connecting rod, and a further member (46, 72, 158) carried by the slide and drivingly connected to the driven rotating member for movement relative to the slide upon rotation of the driven rotating member.

2. A slider crank mechanism as set forth in claim 1, wherein the crank is part of a crankshaft.

3. A slider crank mechanism as set forth in claim 1, wherein the at least one rotary motion transfer member includes an intermediate rotating member (34) rotatably mounted to the connecting rod.

4. A slider crank mechanism as set forth in claim 3, wherein the driving rotary member, driven rotary member and intermediate rotating member are gears.

5. A slider crank mechanism as set forth in claim 1, wherein the at least one rotary motion transfer member includes a belt.

6. A slider crank mechanism as set forth in claim 5, wherein the driving rotary member and driven rotary member are toothed wheels, and the belt is trained around the toothed wheels.

7. A slider crank mechanism as set forth in claim 1, wherein a cam (44, 44′, 152) is rotated by the driven rotating member, and the further member is a cam follower (46, 82, 158) engaged with the cam.

8. A slider crank mechanism as set forth in claim 7, wherein the cam follower is mounted to the slide for back and forth motion.