US2765731A - Hydraulic ram caps for crushing and pressing rolls - Google Patents

Description

Oct. 9, 1956 J. N. EDWARDS HYDRAULIC RAM CAPS FOR CRUSHING AND PRESSING ROLLS Filed March 28, 1952 2 Sheets-Sheet l l 3 ATTORNEYS Oct. 9, 1956 J. N. EDWARDS HYDRAULIC RAM CAPS FOR CRUSHING AND PRESSING ROLLS 2 Sheets-Sheet 2 Filed March 28, 1952 INVENTOR .hsepk/MEdu/ards BY pm 7W #1 r ATTORNEYS States HYDRAULIC RAM CAPS FOR CRUSHING AND PRESSING ROLLS Application March 28, 1952, Serial No. 279,236

6 Claims. (Cl. 100-99) Although the present invention may be utilized in the applying of pressure to a bodily movable roller in various types of machines, it is particularly applicable to that type of sugar cane crushing mill which has a pair of lower parallel rolls and a superposed vertically movable pressure roll. Such rolls are usually mounted in triangular relationship with means for applying hydraulic pressure downwardly on the bearings of the upper rolls. When used in a sugar cane mill they act to apply crushing and juice extracting pressure on the cane passing over the lower rolls and beneath the upper one.

As the thickness of the mat of cane or other material being treated may vary across the width of the mill, and as non-crushable bodies such as stones, metal scrap, or even small tools may be present in or on the cane mat, it is common practice to have the bearings of the upper roll so constructed that the ends of the upper roll may move up and down vertically in respect to the lower rolls, and in respect to each other. Pressure is usually applied to the separate bearings at the ends of the upper roll by means of a fluid delivered to vertical stationary cylinders on the frame and acting on pistons movable up and down in said cylinders and against such pressure, to yieldingly press down plungers acting on the bearing blocks of the upper roll. Thus the ends of the upper roll may move up and down independently of each other. Such a construction is shown in my prior application, Serial No. 120,838, filed October 2, 1949 (now Patent No. 2,691,339 of October 12, 1954), in which hydraulic accumulators which produce the pressure may be mounted directly on the mill roll frame, or may be connected thereto by flexible tubing.

As the material passing over the back roll (often referred to as the bagasse roll), has already been crushed in passing over the front roll (often referred to as the feed roll), and as the opening between the top roll and the back roll is always smaller than the opening between the top roll and the front roll, there is imparted to the top roll a resultant force, at an angle to the vertical, and in a direction away from the bagasse roll. Thus the top roll exerts a corresponding lateral thrust against its bearmgs.

As the bearings wear, the thrust against the pressure plate, and through it against the plunger and piston in the cylinder, is not transferred in a true vertical direction but in the direction of the resultant force on the top roll. Differences in the thickness of the mat across its width also cause dififerences in the extent of the vertical movement of the two ends of the upper roll, and result in pressure tending to tilt or cock the plungers or pistons in the cylinders.

Any tendency of the plungers or pistons to cock causes the pistons and cylinders to wear unevenly, and eventually become scratched, galled or scored. As the wear increases, the tendency to cock, bind and stick becomes progressively greater. In that condition they prevent proper and spontaneous lift and fall of the top roll. This causes serious troubles in mill operations, including (1) atent ice 2 increased difiiculty in feeding the mill; (2) loss of grinding capacity; (3) lowered etiiciency of extraction; (4) increased power consumption; and (5) excessive wear and strain on mill rolls, frame and gearing.

The usual piston in such machines has an inverted cup leather or washer on its top, which acts as a seal against oil leakage, but it prevents any lubrication of the periphery of the piston head. Without lubrication there occur binding, gouging, scoring or excessive and uneven Wear and deterioration of the walls of the cylinder, piston and plunger, and as a result there is cocking, binding, sticking, and increased wear and power consumption.

In carrying out my invention there is provided a new and improved hydraulic ram cap assembly that completely eliminates the well known defects in other ram cap piston assembly designs and has many proven advantages over all other types.

One object of my invention is to provide a new type of ram cap piston packing wherein there are eliminated the hydraulic cup leathers which are usually located on top of the piston and which prevent lubrication of the piston. I obtain complete lubrication by using a ring type of packing near the bottom of the piston head, and thus lubrication along the entire length of the piston above this packing ring is made possible.

As an important feature of my invention the piston is made comparatively long in respect to its diameter so as to effectively resist strains tending to tilt or cock it in the cylinder, and means are provided for securing effective lubrication along its peripheral surface.

As a further feature the piston is provided with a pack ing ring adjacent to its end farthest from the surface receiving the pressure, so that a lubricating oil may be employed as the pressure applying fluid, and may pass down along the major portion of the periphery of the piston and keep it effectively lubricated. v

As a further feature of my invention, circumferential grooves are formed in the periphery of the piston, which enable the hydraulic pressure oil on the top of the piston to act on the side of the piston. The oil in the grooves is under high pressure, and places the piston in hydraulic balance, with equal pressure and lubrication on the entire peripheral surface above the packing ring, which is located near the lower end of the piston. This hydraulic balance and pressure lubrication assures free piston movement and prevents binding, sticking and cocking. Thus, by means of my invention the ram piston is always fully lubricated and is hydraulically balanced.

As a further feature, the packing at the lower end of the piston includes a ring, circular in cross-section, resilient and non-porous, and which presses against the cylinder wall so that the clearance between the piston periphery and the cylinder wall may be substantially less than in prior constructions. This ring will be hereinafter re- I ferred to as an O-ring.

As a further feature, there is associated with the O-ring a porous washer or ring which may be of leather, and which will absorb lubricant and distribute it along the cylinder wall.

By reason of these features the outside diameter of the piston may be increased so that there will be a much closer fit between the periphery of the piston and the inside of the cylinder than has been heretofore practical, and the tendency of the piston to cook, bind, gall or stick is reduced because of this closer fit 'of a lubricated surface which extends along the length of the long piston head, and there is seldom any necessity for replacing the O-ring packing.

A further object is to provide a removable cylinder or liner which will not expand or burst under pressure, and which does not require a pressed fit in the cylinder. This liner preferably has a ground chrome finish on the inside of the cylinder which is practically indestructible, and assures long wear, protects the type of packing used, and minimizes friction. This liner can be easily slipped into place or removed, whereas prior ram cap liners were usually pressed into the housing and could not be removed, and had to be machined or bored out.

By means of my invention the hydraulic ram cap can operate at pressures of 5000 p. s. i. and over without leakage or packing failure, and the ram piston assembly is sealed to prevent dust, dirt or foreign particles from reaching the packing ring or piston, thus causing damage. This seal is accomplished by the wiper or scraper strip attached to the bottom of the ram cap and encircling the piston plunger, and an additional seal is etfected by a felt ring on the piston head below the packing ring.

A further object of my invention is to provide an oil reservoir below the piston head, which will act as a dust seal, lubricate the section of the piston head below the packing ring, and lubricate the plunger.

As a further feature of my invention the oil reservoir below the piston head is connected to a liquid level gauge which serves as a roll movement indicator, roll movement recorder or similar instruments which will clearly show the extent of the movement of the top roll of the mill as the oil moves in and out of the reservoir as the roll moves up and down.

In the accompanying drawings certain embodiments of my invention are illustrated. In these drawings:

Fig. l is an end view, largely in section, of a conventional type of 3-roll mill, and embodying the invention.

Fig. 2 is a vertical section through a portion of a modified form of the cylinder head, and on a larger scale.

Fig. 3 is a similar section through a portion of the piston in which the piston head is shown in sliding engagement with the inner wall of the cylinder.

Fig. 4 is a similar section through the wiper for the plunger or piston extension.

Fig. 5 is a perspective view of the piston, plunger and bearing for the roll.

Fig. 6 is a perspective view of the cylinder head, the liner, the piston and its plunger, and the wiper ring, in spaced relationship.

Fig. 7 is a view, partly in section, showing another form of indicator.

Figs. 8, 10, 12 and 14 are end views of other types of plunger which may be used, and

Figs. 9, 11, 13 and are side elevations of the plungers shown in Figs. 8, 1O, 12 and 14, respectively.

The present invention is shown as applied to a mill of the type having a pair of lower rolls 10 and 11 rotatable in the same direction, and an upper roll 12 driven in the same direction. The upper roll has its shaft 13 mounted in bearings 14 which are independently movable vertically in accordance with the thickness of the mat passing beneath it and over the lower rolls, and with variations in the thickness across the Width of the mat. On each bearing is a plate 15, and each end frame has a vertical ram cap cylinder 16. In each cylinder is a piston 17 having a plunger 18 of smaller diameter which acts on the bearing plate 15. Thus upward movement of the upper roll 12 is yieldingly resisted and the desired pressure is applied to the material passing over the rolls Fri) and 11 and beneath the roll 12, even though the thickness of the mat of material may vary.

In my improved construction the ram cap cylinder has a removable steel liner 19 which is secured in place by a removable cylinder head 20. This head is so connected to the cylinder that it may apply endwise pressure on the end of the liner l lock it in position, and permit its ready removal. threads and be screwed into place and readily removed, it is shown as having a lower portion 21 fitting into the upper end of the liner, and spaced flange sections 22 which may be inserted between flanges 23 on the cylinder. The portions and 21 may be integral, as shown in Although the head may have screw 1 Figs. 2 and 6, or may be of two parts bolted together, as shown in Fig. l. The flanges have annularly inclined under surfaces for forcing the head into engagement with the end of the liner. Thus, upon inserting and rotating the head, it tightly clamps or breech locks the liner 19 in place. The lower portion of the head, which extends into the upper end of the liner 19, has sealing engagement therewith. As shown in Fig. 2, this lower portion has a peripheral groove in which is mounted a gasket 24 and a compressible rubber ring 25. Thus an oil-tight seal is effected without the use of bolts or screws, and the cylinder head may be easily and quickly removed whenever desirable. It may be screwed into place instead of having a bayonet connection as illustrated.

The body portion of the piston 17 is preferably of a length substantially equal to or greater than its diameter so as to better resist tilting movement, and the piston rod or plunger 18 seats in a plate or collar 27 which is provided with flanges 28, each having its under surface presenting a transversely extending groove seating on a convex surface of the bearing plate i5. Thus the bearing 14 and plate 15 may tilt horizontally in respect to the piston as one end of the top roll 12 rises or lowers in respect to the other end, but flange 28, which extends out from collar 27, holds bearing 14 and plate 15 in true vertical alignment, thus preventing bearing 14 from rotating or cocking against its guide plate.

As an important feature, the portion of the cylinder 16 below the piston and around the plunger 18 is filled with lubricating oil, and is connected by a pipe 30 to a vertical chamber or reservoir 31. Thus, as the plunger moves up and down the oil surges back and forth to and from this chamber 31, and therefore the oil level in the chamber fluctuates with up and down movement of the end of the top roll. This variation in the oil level in the chamber is utilized to indicate the up and down movement of the end of the upper pressure roll 12.

As shown in Fig. l the chamber 31 has a transparent wall which may be calibrated, or there may be a suitable scale 32 adjacent thereto. A float 33 is employed in the chamber and it is clearly visible through the chamber wall. Thus the thickness of the mat passing beneath the upper roll 12 is clearly indicated on the scale. The frame at each side of the mill is provided with one of these indicators, and any tilting of the upper roll 12 due to unevenness of the thickness of the mat across its width is clearly shown. As the cross-sectional area of the chamber 31 is very much less than that of the cylinder, the vertical movement of the float is greatly in excess of that of the top roll, and even small movements of the latter will be clearly indicated.

The pressure fluid which acts on the piston is supplied preferably from a pressure accumulator which includes a casing 34 having a flexible wall 34a dividing it into two chambers or compartments, one for compressed gas and the other for liquid. This accumulator may be mounted directly on the frame of the mill, or may be separately mounted and connected to the pressure cylinder by flexible tubing. As shown, the oil containing chamber is directly connected to the cylinder head by a rigid tube 35, and the other chamber may be filled with a gas under high pressure. The tube may be screwed into the cylinder head, or may have a nut on the inner end to better insure against the tube being forced out. Thus the upward movement of the upper roll forces liquid from the upper end of the cylinder into the accumulator, and such transfer of liquid is resisted but permitted by reason of the expansible character of the compressed gas in the accumulator.

As indicated in Fig. 1, and shown on a larger scale in Fig. 3, the piston 17 has a packing only at the lower end portion thereof. This includes a packing ring 39 of resilient material in a groove 37, and between a pair of washers 38 which increase the efliciency of the O-ring when higher pressures are used. Thus the pressure fluid shown in Fig. 3.

which has lubricating properties, and which is delivered through pipe 35, may be applied to substantially the entire periphery of the plunger 18, and prevents galling, binding or sticking of the plunger. In addition, to provide lubrication and to protect the O-ring packing there may be provided an oiled felt ring 41 below this O-ring. Above the O-ring the body portion of the piston 17 has along substantially its entire length, and above the ring 39, a plurality of annular grooves 374, which serve as channels for distributing the lubricant from the pressure chamber above piston 17 down to the compressible ring 39. As later pointed out, these grooves may be formed in various different ways.

To prevent leakage of the oil from the chamber around the plunger and along the latter there is provided a packing which acts as a wiper. As shown on a larger scale in Fig. 4, this includes a ring 60 having a rubber gasket 62 provided with a flexible outwardly inclined flange 63 pressing against the periphery of the plunger 18.

In Fig. 7 there is shown an alternative type of gauge.

In this form there is a piston 45 in the oil gauge chamber 31a, and having a spring for pressing it downwardly. The piston is connected to a cable 46 passing over a pulley 47 to a light weight 48. The pulley is connected to a pointer 49 movable over a scale 50. Thus, the extent to which the piston moves up and down may be readily ascertained.

In Figs. 8 to 15 there are shown several alternative forms of the combined piston and pressure applying plunger.

In Figs. 8 and 9 the piston 17a has a single wide groove 51 above the packing rings which may be of the type This wide groove may be connected by radial passages 52 to a central passage 53, and the lower surface of the plunger is shown as convex.

In Figs. 10 and 11 there are shown a plurality of annular grooves 54 connected together by longitudinal grooves 55 on the periphery, and leading to the top surface of the plunger.

In Figs. 12 and 13 the grooves are as in Figs. 10 and 11, but instead of longitudinal grooves on the periphery there are radial passages 56 leading to a central passage 57.

In Figs. 14 and 15 there is shown a single helical groove 58 on the periphery, and with one end thereof open at the face of the piston.

In all of these forms the grooves transmit oil to the periphery of the piston to balance lateral pressure and effect lubrication.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A ram cap for a crushing mill of the type having a pair of lower rolls and an upper roll mounted in vertically movable bearings, said cap having means for applying downward pressure to said upper roll, said means including a cylinder having a piston therein, a plunger connected to said piston and of smaller diameter, coacting with the cylinder to form an oil chamber in the cylinder below the piston and around said plunger, and a lubricant reservoir connected to and communicating solely with said oil chamber for keeping the latter filled with oil, said reservoir having a transparent portion whereby up and down movements of the piston and upper roll are shown by the variation in the visible level of the oil in said reservoir.

2. A ram cap for a movable bearing for the crushing roll of a crushing mill, comprising, in combination, at each end of said crushing roll, a cylinder for receiving pressure applying and lubricating liquid, a piston head contained within and having its periphery in sliding engagement with the inner surface of said cylinder, said pressure applying and lubricating liquid acting on said piston head, the length of the periphery of said piston head being greater than its diameter, a plunger having one end connected to the base of said piston head and the other end to said movable bearing, said plunger being of a lesser diameter than said piston head, said piston head having in its periphery which is in sliding engagement with said cylinder a narrow, resilient, non-porus, peripheral packing ring at the lower end only of the piston head above and adjacent the said plunger leaving the major portion of the peripheral surface of the piston head above said packing ring in direct sliding engagement with the inner surf-ace of said cylinder, whereby the pressure applying and lubricating liquid has access to said major portion of the peripheral surface of the piston head and lubricates the same and the piston head resists tilting movement of said crushing roll, and a reservoir for lubricating and pressure applying liquid communicating with said cylinder for supplying to said cylinder said lubricating and pressure applying liquid and thus continuously lubricating the peripheral surface of said piston head in sliding engagement with the inner surface of said cylinder.

'3. A ram cap for crushing mills as defined in claim 2, in which said resilient non-porous packing ring is circular in cross section.

4. A ram cap for crushing mills as defined in claim 2 in which said resilient non-porous packing ring is circular in cross section and is confined between two leather washers above and below said packing ring.

5. A ram cap for a crushing mill of the type having a lower roll, and an upper roll having vertically moving bearings, said cap including a lined cylinder for lubricating and pressure-applying liquid, a piston of a length greater than its diameter in said cylinder, a plunger having one end connected to said piston and the other end to a bearing for said upper roll, said plunger being of smaller diameter than said piston to form an annular chamber in said cylinder and around said plunger, a narrow ring of resilient non-porous packing on said piston, said ring being disposed only at the end of said piston adjacent said plunger leaving substantially the entire peripheral surface of said piston in sliding engagement with the inner surface of said lined cylinder whereby the lubricating and pressure-applying liquid has access to substantially the entire peripheral surface of said piston and lubricates the same, a reservoir for lubricating and pressure-applying liquid communicating with the cylinder to keep said cylinder full of lubricating and pressureapplying liquid and thus lubricating at all times the liner of said cylinder and substantially the entire area of said piston, and 'a lubricating container connected solely with said annular chamber surrounding said plunger to maintain a body of lubricant in said annular chamber to lubricate said piston and to provide a dust seal for said piston.

6. A ram cap for crushing mills as defined in claim 5, in which the reservoir is equipped with means to maintain the lubricating and pressure-applying liquids supplied to said lined cylinder under high pressure, the periphery of the piston above said packing ring is provided with a plurality of grooves therein which serve as channels for distributing the lubricating liquid from the said reservoir to the peripheral surface of the piston and the lined surface of the cylinder and places the piston in hydraulic balance with equal pressure and lubrication of the peripheral surface thereof, the packing ring is circular in cross-section and is confined between a pair of leather washers above and below said packing ring, and the lubricant container is provided with means for indicating the extent to which the lubricant flows back and forth between said container and said annular chamber as said piston and plunger move up and down thus indicating the extent of the movement of said upper roll of the mill.

References Cited in the file of this patent UNITED STATES PATENTS 358,285 Maxey Feb. 22, 1887 (Other references on following page) 7 UNITED STATES PATENTS Miller May 7, 1889 Ambrose Feb. 18, 1890 Braden July 2, 1895 Boyer Nov. 22, 1910 Bancroft Apr. 28, 1914 Philen Feb. 7, 1928 Marien Aug. 5, 1930 Jardine Sept. 20, 1938 Parkins Oct. 8, 1946 Bechtold et a1 June 28, 1949 8 Yates et a1 Mar. 28, 1950 Hagenbarth July 4, 1950 May Aug. 13, 1952 Edwards Oct. 12, 1954 FOREIGN PATENTS Great Britain 1911 Great Britain 1911 Great Britain Feb. 15, 1917 Great Britain Apr. 15, 1932 France Sept. 21, 1926

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