GB1578373A - Presses - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO PRESSES (71) We, VORONEZHSKY LESOTEKHNI- CHESKY INSTITUT, a Corporation organised and existing under the laws of the Union of Soviet Socialist Republics, of Timiryazeva, 8, Voronezh, U.S.S.R., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particu larly described in and by the following statement: The present invention relates to mechanical presses.

According to the invention there is provided a mechanical press comprising a frame, an operating element formed by a slide reciprocal in guides of the frame and biased towards an initial position by a balancer mounted on the frame, a flywheel rigidly mounted on a shaft provided with an eccentric, a collapsible pitman linkage con nected between the eccentric and the slide, and a controllable locking device for locking a link of the pitman linkage in a fixed posi tion relative to either the slide or another link of the pitman linkage whereby to cause the pitman linkage to drive the slide through a working stroke, the pitman linkage being otherwise inoperative to transmit drive from the eccentric to the slide, said locking device being so arranged that locking can only be initiated when the slide occupies its initial position, the balancer being a floating balancer adjustable in a manner enabling adjustment of the initial position of the slide, and the press further comprising control means for actuating the locking device at the moment when the links of the pitman linkage are temporarily stationary during their cycle of motion executed under the effect of rotation of the eccentric.

Location of the locking device on the slide or on one of the pitman links creates a simple and compact press-starting mechanism which enhances its reliability and life.

The shaft with its eccentric can be rotated continuously which enables a constant oil clearance to be maintained in its supporting bearings; furthermore, power is not required for acceleration and braking during singlestroke operation of the press.

The fact that the locking device locks the links of the collapsible pitman at the moment when said links reach a zero speed eliminates dynamic impact loads during starting of the press and avoids friction losses inherent in presses whose drives incorporate a friction clutch and a brake. Consequently, relatively high power factors can be achieved. Furthermore, the clutch and the brake limit the efficiency of the known mechanical presses and inhibit improvement of their output during single-stroke operation.

The use of the adjustable floating balancer ensures that initiation of a working stroke of the press can only take place when the slide occupies its initial upper position. The balancer also enables adjustment of the initial position of the slide to enable the operator to adjust the press working stroke.

A mechanical press embodying the invention will now be particularly described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a part-sectional general view of the mechanical press; Figure 2 is a view along arrow A in Figure 1; Figure 3 is a section on line III-III of Figure 1 showing one form of locking device of the press; Figure 4 shows another form of locking device for the press; Figure 5 is a part-sectional side view of the press showing the positioning of a locking device on a pitman link of the press; Figure 6 is a section on line VI-VI of Figure 5; Figure 7 is a section on line VII-VII of Figure 6; Figure 8 shows a further form of locking device mounted on a pitman link of the press; Figure 9 is a section on line IX-IX of Figure 8; Figure 10 is a section on line X-X of Figure 8; and Figure 11 is a section on line XI-XI of Figure 9.

The mechanical press (Figure 1) comprises a frame 1 accommodating a shaft 2 driven by a flywheel rigidly secured on said shaft and coupled by a flexible transmission with an electric motor (not shown in the drawing).

The shaft 2 carries an eccentric 3, which is rotatably installed in an upper link 4 which is articulated by a pivot 5 with a lower link 6.

The upper link 4, pivot 5, and lower link 6 together constitute a collapsible pitman linkage which is located above an operating element of the press, i.e. above a two-part slide which is connected with the pitman by a pivot 7 and consists of an outer portion 8 with a screw 9 and an inner portion 10 with a worm wheel 11 and a worm 12. The worm wheel 11 is screw-threadedly engaged by the screw 9. The axes of the worm wheel 11 and screw 9 coincide with the axis of movement of the slide.

The outer portion 8 of the slide is installed in guides of the frame 1 with provision for vertical motion while the inner portion 10 is installed in guides (for example of a dovetail type) inside the outer portion of the slide.

The inner portion is movable vertically relative to the outer portion of the slide by rotation of the worm wheel 11 about the screw 9 to cause relative axial movement therebetween. The worm wheel is rotatable by the worm 12.

The outer portion 8 of the slide is articulated by a pivot 13 with a floating balancer made in the form of a cylinder 16 housing a piston which is connected by its rod 14 to the pivot 13 and is loaded by a spring 17.

The balancer cylinder 16 is articulated by a pivot 18 with a lever-adjusting device (Figures 1, 2) which consists of a lever 19 extending through a port of the frame 1 and provided with a hub 20 which is mounted rigidly on a shaft 21 rotatable in supporting bushings 22 carried by uprights 23 of a plate 24 secured on the press frame 1. Rigidly secured to a cantilever portion of the shaft 21 is the hub 25 of a lever 26 whose end is connected by a pivot 27 with an adjusting rod 28 having two locking wheels 29 and a stop 30. A flange 31 of the stop 30 is screwed to the press frame 1.

The action of the press is controlled by a locking device 33 which itself is controlled by a control unit (not shown). The locking device 33 is secured by means of an shaped bracket 32 (Figure 1) to the front of the slide outer portion 8.

The locking device 33 consists of two electromagnets rigidly mounted on the bracket 32 and each comprising a body 34 with a coil 35 which interacts with a moveable armature 36. The armature 36 is adjustably mounted on studs 37 by adjusting nuts 38 which engage with threaded end portions of the studs 37. The studs 37 are slidably mounted on the body 34 in guide bushings 43 and connect with a disc 39 which is provided with a through central guide hole 40 and an operating element 41 in the form of a tapered circular projection. The armature 36 is loaded with return springs 42 which encompass the studs 37 and react between the guide bushings 43 and washers 44 of the adiusting nuts 38. When the coil 35 is un-energised, the armature 36 is spaced from the body 34 while the disc 39 is drawn towards the body 34. A cylindrical end portion of a fixed core 45 protrudes centrally from the electromagnet body 34 into the guide hole 40 of the disc 39. The core 45 screw-threadedly engages in the bottom of the body 34 and the tapered head of the core 45 retains the electromagnet coil against axial displacement.

The front side of the pitman lower link 6 is provided with a blind slot in which a lock plate 47 is rigidly secured by screws 46. The lock plate 47 has two back-to-back tapered holes 48 engageable by respective ones of the operating elements 41 of the discs 39 to lock the lower link 6 in a predetermined position relative to the slide.

The collapsible pitman linkage is so arranged that when the links 4 and 6 are in the extreme right hand position (see Figure 1) the eccentric 3 is in its uppermost position, the links 4 and 6 being just short of alignment with the slide axis. Just at the moment the links 4 and 6 reach their extreme righthand position, their speed is zero, and it is at this moment that the locking device 33 is energised on command from th control unit to move the operating elements 41 into the holes 48 of the plate 47 to lock the link 6 in a position determined by the design and arrangement of the locking device and of the links of the collapsible pitman. During subsequent rotation of the eccentric shaft 2, the slide reciprocates vertically with the collapsible pitman links 4, 6 set at an angle to each other; this effects a working stroke of the press.

With the locking device disengaged, the rotating eccentric 3 turns the pitman links 4 and 6 relative to each other and moves them in uninterrupted motion to the extreme left then back to the extreme right position (idle stroke of the links). Meanwhile, the slide acted upon by the balancer remains stationary in its initial upper position.

Adjustment of the position of the floating balancer by means of the lever-adjusting device enables the upper position of the slide to be moved through a required distance for adjusting the working stroke.

A second form of locking device is shown in Figure 4 and in this device the operating elements have the form of friction discs 49 attached to movable discs 50 and are arranged to effect locking action by clamping the lock plate 47 between them (the plate being in this case a solid body). As a result, the links of the collapsible pitman are fixed and the operating element of the press executes a working stroke.

The above-described mechanical press functions as follows: An electric motor mounted on the frame 1 continuously rotates the flywheel (not shown in the drawings) via a flexible transmission, and said flywheel imparts rotary motion to the shaft 2 whose eccentric 3 rotates in the hole of the upper link 4 of the collapsible pitman.

When the coils 35 of the electromagnets of the locking device 33 are deenergised, the armatures 36 together with the studs 37, adjusting nuts 38 and discs 39 are biased by the return springs 42 to their initial positions in which the locking device of the press is disengaged. Clearances exist between the operating elements 41 of the discs 39 and the lock plate 47.

As the rotating shaft 2 turns the links 4, 6 of the collapsible pitman, these links pivot around the pivot 5. The press slide is held in its initial upper position by the balancer and remains there unaffected by the sideways oscillation of pitman links 4 and 6. When the press is required to effect a working stroke, the control unit is actuated such that the next time the eccentric 3 of the shaft 2 occupies its upper position, the control unit effects energisation of the coils 35 of the electromagnets of the locking device 33. As a result, the discs 39 with the tapered operating elements 41 move towards each other and said operating elements 41 engage in the tapered holes 48 of the lock plate 47. Thus the lock plate 47 is held in the locking device 33 whereby the link 6 is locked in the extreme right hand position.This prevents the pitman linkage from collapsing on further rotation of the shaft 2 so that the downward movement caused by the eccentric 3 as it rotates is transmitted via the pitman linkage to the slide.

Then during further turning of the shaft 2 the press slide is progressively moved to the downmost position so that said slide executes a working operation driven from the press flywheel by the shaft 2, the eccentric 3, the collapsible pitman 4, 5 and 6, the pivot 7, the outer portion 8 of the slide, the screw 9, worm wheel 11 and the inner portion 10 of the slide.

The movement of the slide takes place concurrently with the movement of the movable parts of the balancer, i.e. pivot 13, rod 14 and piston 15 which latter compresses the spring 17.

Should the press be overloaded in operation (if, for example, two blanks are fed simultaneously into the working zone of the press, or the material of the blank is stronger than normal), the resultant force which is higher than normal causes the lock plate 47 to force the discs 39 apart against the force of the electromagnets enabling the lock plate 47 to turn to the left together with the lower link 6 and the upper link 4 of the pitman. As a result, the press slide discontinues its further motion and the press parts are thereby protected automatically against breaking and wedging.

It will be appreciated that operation of the locking device will only be effective when the press slide occupies its initial upper position since with the slide otherwise positioned, the lower link is incorrectly orientated for the operating elements of the locking device to engage.

In the second form of the locking device (Figure 4) when the press is overloaded in operation, the plate 47 slips relative to the locking device operating elements, i.e. friction discs 49 which also protects the press parts automatically against breaking and wedging.

In Figure 5 the mechanical press is shown with a locking device 51 arranged to lock the pitman links 4 and 6 together at a predetermined angle. This device 51 is powered by a fluid under pressure e.g. compressed air delivered into a power cylinder from an air distributor on a signal from a control unit (not shown in the drawing).

The power cylinder consists of two pneumatic diaphragm chambers 52 (Figure 6) arranged symmetrically in recesses provided in the lower link 6 of the collapsible pitman.

Each chamber accommodates an operating element, i.e. rod 53, a spring-loaded pusher 54, a diaphragm 55 held in place by a cover 56 which is screwed to the side surface of the lower link of the pitman, and return springs 57 extending between cylindrical blind holes provided in the bottom of the pneumatic chambers 52 and in the pushers 54.

The lower part of the upper link 4 of the collapsible pitman is provided with a projection 58 (Figure 7) which extends between the two pneumatic chambers 52. The projection 58 has a through slot 59 arranged to receive the operating elements 53 thereby to ensure reliable rigid locking together of the pitman links when the press executes a working stroke.

To lock the links 4 and 6 together, compressed air is fed into the chambers 52 through channels 60 (Fig. 6) in the lower link 6 of the collapsible pitman.

When the power cylinder, i.e. pneumatic chambers 52, is turned off, all the parts come back to their initial positions, with the elements 53 disengaged from the slot 59.

In Figure 8 the press is again shown with a locking device arranged to lock together the links 4 and 6. A power cylinder of this device is actuated similarly to the abovedescribed power cylinder by a fluid under pressure. In the present example, the power cylinder comprises a housing 61 installed in a recess on the front part of the lower link 6 of the pitman, and a detachable cover 62 with a flange secured over the housing 61 by studs 63 with nuts 64. An annular element 66 is slidably mounted on the studs 63 to surround the housing 61 between the front side of the lower link 6 and the cover 62. The element 66 is urged towards the cover 62 by springs 65.

The housing 61 accommodates a piston 67 connected to a push rod 68 made in the form of a gear rack and interacting, via a toothed shaft 69 and control gears 70 (Figure 10) located in the lower link 6, with a turntable locking element 71 of the locking device.

This locking element 71 is profiled to engage when turned through a predetermined angle by operation of the power cylinder, a slot (for example of a segment shape) provided in the lower part of the upper link 4. This engagement locks the links of the pitman relative to each other. When the power cylinder is turned off the locking element 71 is turned to an orientation in which it no longer engages in the slot in the upper link 6.

Two through slots 72 (Figure 11) are provided in the housing 61 in diametrically opposed locations. The centre lines of the slots 72 run parallel with the centre line of the power cylinder. The push rod 68 has a through hole arranged perpcndicularly to the centre line of the power cylinder and the hub of the element 66 fitted around the cylinder also has through holes coinciding with the through slots 72 of the cylinder and with the hole in the push rod. A cylindrical pin 73 (Figure 9) extends through said holes and slots to interconnect the element 66 and the push rod 68. Washers 74 (Figure 11) and cotter pins 75 (Figure 9) installed on the ends of the cylindrical pin 73 keep the pin from falling out of the holes.

The hereinbefore described press exhibits the following desirable properties.

- absence of impact loads during starting and stopping of the press; - automatic protection of the operating element (slide) of the press against breakage in case of overloads and wedging; - a material reduction of the sound pressure level; - lower expenditures of power for turning the press ON and OFF; - wider technological capabilities of the press; - the locking device jointly with the collapsible pitman and slide constitutes a single functional unit of the machine.

Tests have shown that presses of the described form operate more reliably and safer than traditional prior-art presses of similar capacity.

It has also been established experimentally that the levels of sound, sound pressure in the octave bands of frequencies, as well as the sound power levels of the hereinbefore described clutchless press are 14-18db, i.e.

2.6 - 3.5 times lower than those of the known clutch-operated mechanical press of a similar capacity.

The investigation of the frequency composition of the noise produced by the described press has shown that the sound pressure is considerably reduced in all the octave bands. The noise produced by the high-frequency components has dropped considerably, to 15 - 17 db which considerably reduces the noise at the press working station.

Where the locking device is actuated by a power cylinder, it has been found that the amount of compressed air required for one operation of the power cylinder in a 40-ton press of the described form is 44.3 cm3/ stroke whereas the clutch of a prior art press of the same capacity requires 1200 cm3 of air per stroke in a single operation which is 27 times more than in the clutchless press.

Similarly where the locking device is electromagnetically operated, it has been found that for single-stroke duty, the des cribed form of press uses 2.5 - 3 times less electric power than during operation of the prior art press of the same capacity equipped with a clutch and a brake. This is attributed to the fact that the described press is not required during each single operation to accelerate the inertia masses of the friction units (driven discs of the brake and friction discs of the clutch with the hubs of said discs, the eccentric, shaft and pitman).

The total weight of the locking device of the described press is 2 - 4 times lighter than the weight of the parts it replaces in a press of similar capacity with a clutch and brake; this leads to a considerable reduction in the labour and manufacturing cost of the press.

Mechanical presses of the described form can be utilized in automotive and aircraftbuilding industries, in tractor, agricultural and transport machine-building, in the manufacture of metal-working equipment, household facilities, electrical and radio goods, and in other fields of industry.

The described mechanical press can be used for punching, piercing, bending, trimming, calibrating, shallow drawing and other operations involved in cold-pressing of metals.

WHAT WE CLAIM IS:- 1. A mechanical press comprising a frame, an operating element formed by a slide reciprocable in guides of the frame and biased towards an initial position by a balancer mounted on the frame, a flywheel rigidly mounted on a shaft provided with an eccentric, a collapsible pitman linkage connected between the eccentric and the slide, and a controllable locking device for locking a link of the pitman linkage in a fixed position relative to either the slide or another link of the pitman linkage whereby to cause the pitman linkage to drive the slide through a working stroke, the pitman linkkage being otherwise inoperative to transmit drive from the eccentric to the slide, said locking device being so arranged that locking can only be initiated when the slide occupies its initial position, the balancer being a floating balancer adjustable in a manner enabling adjustment of the initial position of the slide, and the press further comprising control means for actuating the locking device at the moment when the links of the pitman linkage are temporarily stationary during their cycle of motion executed under the effect of rotation of the eccentric.

2. A mechanical press as claimed in claim 1, wherein the locking device is mounted on one said pitman link and is arranged to lock that link with another link of the pitman linkage, the locking device being made in the form of a power cylinder provided with a spring-loaded pusher and a diaphragm, a rod carried by the pusher being engageable in a recess in the said another link when the slide occupies its initial position and the links are in a predetermined mutual orientation corresponding to a zero speed position of the links during their cycle of motion.

3. A mechanical press as claimed in claim 2, wherein a housing of the power cylinder is encompassed by an annular element rigidly connected by a pin through slots in the housing with the pusher of the power cylinder.

4. A mechanical press as claimed in claim 1, wherein the locking device is made in the form of at least one electromagnet mounted on the slide and arranged to lock together the slide and one said pitman link.

5. A mechanical press substantially as hereinbefore described with reference to Figures 1 and 2, and Figures 3 or 4 of the accompanying drawings.

6. A mechanical press substantially as hereinbefore described with reference to Figures 5 to 7, or Figures 8 to 11 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. cribed form of press uses 2.5 - 3 times less electric power than during operation of the prior art press of the same capacity equipped with a clutch and a brake. This is attributed to the fact that the described press is not required during each single operation to accelerate the inertia masses of the friction units (driven discs of the brake and friction discs of the clutch with the hubs of said discs, the eccentric, shaft and pitman). The total weight of the locking device of the described press is 2 - 4 times lighter than the weight of the parts it replaces in a press of similar capacity with a clutch and brake; this leads to a considerable reduction in the labour and manufacturing cost of the press. Mechanical presses of the described form can be utilized in automotive and aircraftbuilding industries, in tractor, agricultural and transport machine-building, in the manufacture of metal-working equipment, household facilities, electrical and radio goods, and in other fields of industry. The described mechanical press can be used for punching, piercing, bending, trimming, calibrating, shallow drawing and other operations involved in cold-pressing of metals. WHAT WE CLAIM IS:-

1. A mechanical press comprising a frame, an operating element formed by a slide reciprocable in guides of the frame and biased towards an initial position by a balancer mounted on the frame, a flywheel rigidly mounted on a shaft provided with an eccentric, a collapsible pitman linkage connected between the eccentric and the slide, and a controllable locking device for locking a link of the pitman linkage in a fixed position relative to either the slide or another link of the pitman linkage whereby to cause the pitman linkage to drive the slide through a working stroke, the pitman linkkage being otherwise inoperative to transmit drive from the eccentric to the slide, said locking device being so arranged that locking can only be initiated when the slide occupies its initial position, the balancer being a floating balancer adjustable in a manner enabling adjustment of the initial position of the slide, and the press further comprising control means for actuating the locking device at the moment when the links of the pitman linkage are temporarily stationary during their cycle of motion executed under the effect of rotation of the eccentric.

2. A mechanical press as claimed in claim 1, wherein the locking device is mounted on one said pitman link and is arranged to lock that link with another link of the pitman linkage, the locking device being made in the form of a power cylinder provided with a spring-loaded pusher and a diaphragm, a rod carried by the pusher being engageable in a recess in the said another link when the slide occupies its initial position and the links are in a predetermined mutual orientation corresponding to a zero speed position of the links during their cycle of motion.

3. A mechanical press as claimed in claim 2, wherein a housing of the power cylinder is encompassed by an annular element rigidly connected by a pin through slots in the housing with the pusher of the power cylinder.

4. A mechanical press as claimed in claim 1, wherein the locking device is made in the form of at least one electromagnet mounted on the slide and arranged to lock together the slide and one said pitman link.

5. A mechanical press substantially as hereinbefore described with reference to Figures 1 and 2, and Figures 3 or 4 of the accompanying drawings.

6. A mechanical press substantially as hereinbefore described with reference to Figures 5 to 7, or Figures 8 to 11 of the accompanying drawings.