US3469400A - High speed forging hammer apparatus - Google Patents

Description

Sept. 30, 1969 TADASHI OIKAWA ETAL 3,469,400

HIGH SPEED FORGING HAMMER APPARATUS Filed June 3, 1968 2 Sheets-Sheet l p 0, 1969 TADASHI OIKAWA ETAL 3,469,400

HIGH SPEED FORGING HAMMER APPARATUS 2 Sheets-Sheet 2 Filed June 5. 1968 FIGZ FIG.4

, INVENTORS? TADASHI OIKAWA HIROYASU YAG-UCHI' ATTORNEYS United States Patent 3,469,400 HIGH SPEED FORGING HAMMER APPARATUS Tadashi Oikawa and Hiroyasu Yaguchi, Muroran, Japan, pssignors to Kabushiki Kaisha Nihon Seikosho, Tokyo,

apan Continuation-impart of application Ser. No. 570,342, Aug. 4, 1966. This application June 3, 1968, Ser. No. 736,545 Claims priority, application Japan, Aug. 19, 1965,

0/ 50,139 Int. Cl. F01b 1/02; F1511 15/22 US. Cl. 60-57 4 Claims ABSTRACT OF THE DISCLOSURE A high speed forging hammer apparatus comprising a fluid pressure cylinder and a piston forming a part of a forging drop body. Two cylinder spaces separated by the piston communicate with each other through a small hole extending through the piston or through an external pipe. Both cylinder spaces and the hole or the pipe are connected in a pressure line of a closed loop type through which an operating fluid circulates.

This application is a continuation-in-part of application Ser. No. 570,342, filed Aug. 4, 1966, now abandoned.

This invention relates in general to a high speed forging hammer apparatus and more particularly to a forging hammer apparatus capable of effecting high speed forging, precise forging and continuous forging.

The conventional type of forging hammers may be generally sorted into three kinds; drop hammers utilizing direct mechanical forces, steam hammers utilizing steam,

and air hammers utilizing air. Among them, the air hammer is the most widely used type.

Air hammers utilize, as a power source, compressed air in an open loop system. Therefore, apart from a cooling loss in the associated air compressor, an exhaust loss due to those portions of compressed air being exhausted during the lift and the drop strokes of a drop body is appreciable. Also, it is difficult to control the pressure of the operating air, and among other drawbacks, the hammering force can not be properly controlled through manual operation of a control valve.

Furthermore the conventional type of air hammer has been operated with air at a relatively low pressure and the hammering force depends upon both the weight of the drop hammer involved and the length of its drop stroke. Under these circumstances, an increase in hammering force inevitably leads to use of a large-sized machine. However, as most components of forging hammers are castings, their dimensions are naturally limited. For this reason, it has heretofore been diflicult to produce forging hammers with a high hammering force.

Accordingly, a general object of the invention is to eliminate the above mentioned difliculties.

An object of the invention is to provide a novel and improved high speed forging hammer apparatus operating with an operating fluid having a controllable pressure with a very low exhaust loss and providing a hammering force precisely controllable at will under mechanical control.

Another object of the invention is to provide a novel and improved high speed forging hammer apparatus relatively small in dimension and yet having a greatly increased hammering force by increasing the fluid pressure and dropping a drop body at the maximum possible speed.

With the foresaid objects in view, the invention resides in a high speed forging hammer apparatus comprising a vertical operating cylinder member, a piston member ice slidable within the cylinder member and dividing the interior of the cylinder member into an upper cylinder space and a lower cylinder space, the piston member forming a part of a drop body, and a fluid circulation system including the upper and lower cylinder spaces to drive the piston member, characterized in that means are provided for communicating the upper cylinder space with the lower cylinder space, whereby the fluid circulation system is arranged to form a closed loop circuit.

In a preferred embodiment of the invention, a high speed forging hammer apparatus may comprise a vertical operating cylinder member, apiston member vertically slidable within the cylinder member and dividing the interior of the cylinder member into an upper cylinder space and a lower cylinder space, an upper piston rod projecting from the piston member into the upper cylinder space, a lower piston rod projecting from the piston member into the lower cylinder member and further extending externally of the cylinder member, the upper piston rod being greater in diameter than the lower piston rod, a ram connected to the lower end portion of the lower piston rod, the piston, the upper and lower piston rods, and the ram forming a drop body, a reservoir including a higher pressure chamber having fluid under a higher pressure contained therein and a lower pressure chamber having fluid under a lower pressure contained therein, a first duct means for connecting the upper cylinder space with the higher pressure reservoir chamber, a control valve disposed in the first duct means to control a flow of fluid under a higher pressure into the upper cylinder space, second duct means for communicating the lower cylinder space with the lower pressure reservoir chamber, starting means responsive to the position of the piston member to actuate the control valve and also to start the piston member, and a compressor means for pressurizing fluid from the lower pressure reservoir chamber and feeding the pressurized fluid into the higher pressure reservoir chamber, characterized in that piston member is provided with a small hole axially extending therethrough to connect the upper cylinder space with the lower cylinder space, and that the higher pressure reservoir chamber, the first duct means, the upper cylinder space, the hole in the piston member, the lower cylinder space, the second duct means, the lower pressure reservoir chamber and the compressor means are arranged to form a closed loop circuit.

Alternatively, thes upper cylinder space may be connected with the lower cylinder through an external pipe instead of by the hole in the piston member. In order to control the rate at which the difference of pressure between the upper and lower cylinder space decreases and also to control the lifting speed of the piston member, a flow adjusting valve is preferably disposed in the external pipe.

The invention, its organization and its mode of operation, as well as other objects and advantages thereof, will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevational view, partly in longitudinal section, of one embodiment of a high speedforging hammer apparatus according to the invention;

FIGS. 2, 3 and 4 are fragmental sectional views illustrating relative positions of the piston, cylinder, valve, etc. of the apparatus shown in FIG. 1 in different operating positions; and

FIG. 5 is a fragmental longitudinal sectional view of a modification of the invention.

Referring now to the drawings, and more particularly to FIG. 1, there is illustrated a high speed forging hammer apparatus embodying the features of the invention.

The arrangement illustrated comprises a pair of vertical frames and 11 disposed symmetrically with respect to the longitudinal axis of the apparatus. The frames 10 and 11 can be made, for example, of a cast iron and their opposed internal side surfaces have disposed thereon a pair of guide bars 12 and 13, respectively, which can be made, for example, of a cast steel. The frames 10 and 11 are rigidly secured to an anvil block 14 which, in turn, is disposed on a rigid foundation. Rigidly secured at the upper ends of the frames 10 and 11 is a spacer plate or tie plate 16 of cast iron upon which are mounted a vertical operating cylinder unit comprising a cylinder body 18 and a cylinder cap 20 secured thereto. Thus the interior or cylinder chamber of the cylinder body 18 is closed at both ends except in the regions of piston rods which will be subsequently described.

Slidably fitted into the cylinder chamber 18 is a piston 22 which divides the cylinder chamber into an upper and a lower cylinder space 24 and 25. The piston 22 is provided on the upper surface thereof with an upper piston rod 26 extending through the cylinder cap 20 and similarly on the lower surface with a lower piston rod 27 extending through the lower cylinder space and slidably extending through the bottom of the cylinder chamber until it projects into a space between the frames 10 and 11. The lower piston rod 27 has secured on the lower end portion a ram 28 which in turn has on its lower end an upper tap 30. The ram 28 can be made, for example, of a cast steel and is adapted to be guided along the guide bars 12 and 13 on the side frame surfaces. Thus it will be appreciated that the piston 22, the upper and lower piston rods 26 and 27, respectively, and the ram 28 are connected together to form a drop body. It is to be noted that the upper piston rod 26 is longer in diameter than the lower piston rod 27 and therefore that the piston 22 has a smaller upper surface in pressure receiving area than the lower surface, for a reason which will be described hereinafter.

A stationary lower tap 32 is rigidly secured on the anvil block 14 in such a position that the drop body can strike the same.

In order to prevent an operating fluid under pressure from passing from the upper cylinder space 24 to the lower cylinder space 25 and vice versa through an annular clearance between the sliding cylindrical surface of the piston 22 and the adjacent portion of the internal peripheral surface of the cylinder 18, the sliding surface of the piston is provided with a set of piston rings 34 of conventional construction. Also, in order to prevent the fluid from leaking from the cylinder chamber through both ends, upper and lower packings 26 and 27, respectively, are disposed on the cylinder cap 20 and the bottom of the cylinder chamber 18 around those portions of the upper and lower piston rods 26 and 27 extending through the latter.

As shown in FIG. 1, the upper end surface of the piston 22 is recessed at 38 except for the outermost annular portion, that annular portion adjacent the sliding surface providing an annular land 40 for a reason which will be apparent hereinafter. Bored in the recessed portion 38 is a small hole 42 extending axially through the piston 22 for a purpose which will be described later.

As also shown in FIG. 1, the lower surface of the cylinder cap 20 forming the upper end surface of the cylinder is provided with an annular seat 44 in such a position that when the piston 20 reaches its uppermost position, the annular land 40 on the piston 22 rests against the seat 44, thereby acting in a manner resembling a valve in the closed position.

Mounted on the lower side of the cylinder cap 20 is a high pressure annular chamber 46 extending around the upper end portion of the cylinder chamber 18. The annular chamber 46 has formed on the internal wall surface a plurality of circumferentially spaced entrance ports 48 opening into the cylinder chamber 18. The entrance ports 48 serve normally to connect the annular chamber 46 with the cylinder chamber 18, but they are adapted to be closed by the upper end portion of the piston 22 only when the latter is located at its uppermost position. Disposed within the annular chamber 46 is a control valve 50 for controlling a flow of fluid under pressure through a valve port 52 into the annular chamber 46.

The cylinder body 18 has formed in the lower end portion a discharge port 54 through which the fluid can be discharged from the lower cylinder space 25.

As shown in FIG. 1, an inverted Vshaped bracket 56 is rigidly secured on the upper surface of the cylinder cap 20 and is provided on its flat apex with a starting device 58, which may be of a conventional design. The starting device 58 includes a feeler 60 projecting between the two legs of the V and adapted to contact the upper end of the upper rod 26 when the drop body reaches its uppermost position. This device is adapted to be externally operated to start the piston 22.

As shown in FIG. 2, a pair of solenoid valves 81 and 82 are for supplying fluid to close the control 50 and to supply fluid to the feeler 60 of the starting device 58 to cause the feeler to exert a downwardly directed force by a fluid pressure. A sensing means such as a limit switch 83 is provided on the inner surface of the top of bracket 56 to sense the return of the drop body to its uppermost position. The limit switch is connected to the solenoid valve 82 to energize it to a position to open valve 50. The solenoid valve 81 has a timer 81a connected thereto to reset valve 81 automatically to the position to disconnect pressure fluid from feeler 60.

In order to operate the forging hammer unit as above described a fluid reservoir generally designated by the reference numeral 62 is disposed on a concrete foundation 64 and externally of the forging hammer unit. The reservoir 62 includes a lower pressure chamber 66 containing a fluid under a lower pressure and a higher pres sure chamber 67 containing the fluid under a higher pressure. The lower pressure chamber 66 includes an entrance port 68 connected to the discharge port 54 on the cylinder by a duct 69 and an exit port 70 connected to a high pressure compressor 72 on the suction side through a discharge port 71. The higher pressure chamber 67 includes an entrance port 74 connected to the discharge side of the compressor 72 by a pipe 75 and a delivery port 76 connected to the valve port 52 by a duct 77.

From the foregoing, it should be appreciated that the fluid circulating system can be traced from the higher pressure reservoir chamber 67 through the duct 77, the control valve 50, the upper cylinder space 24, the hole 42 in the piston 22, the lower cylinder space 25, the duct 69, the lower pressure reservoir chamber 66 and the pipe 71 to the compressor 72 where the fluid is pressurized, and thence to the higher pressure reservoir 67 through the duct 77, these elements forming a closed loop circuit by which the invention is characterized.

As in the conventional type of air forging hammer apparatus, the lower pressure reservoir chamber 66 includes a fluid replenishing port and each of the reservoir chambers 66 and 67 has various suitable connections for a manometer and a safety valve, although these components are not illustrated in FIG. 1 for purpose of simplification.

The apparatus above described is operated as follows: It is assumed that the high pressure compressor 72 is always in operation to suck a fluid under a lower pressure within the lower pressure reservoir chamber 66 into the same and to pressurize the fluid which, in turn, is discharged into the higher pressure reservoir chamber 67 as an operating fluid under a higher pressure. It is also assumed that the compressor 72 includes a control means (not shown) for setting any desired discharge pressure and that the higher pressure reservoir chamber 67 has a sufliciently high capacity. Under these assumed conditions, the operating fluid has the pressure always maintained substantially at the preset magnitude and is prevented from exceeding that magnitude. Further, it is assumed that the closed loop type fluid circulation sys tem is filled with a predetermined volume of operating fluid and that the lower pressure reservoir chamber 66 has a sufficiently high capacity. Therefore the fluid under the lower pressure is maintained constant in volume. It should be understood that, in order to compensate for spontaneous leakage of the fluid, the latter can be replenished from time to time, thereby to prevent any decrease in fluid pressure.

One cycle of operation will now be described in conjunction with FIGS. 1 to 4 inclusive. FIG. 3 illustrates the drop body comprising the piston 22, the upper and lower piston rods 26 and 27, respectively, and the rain 28 at the limit of the lift stroke or its uppermost position. In the position illustrated, the control valve 50 is in its closed position and the pressures exerted on the upper and lower surfaces of the piston 22 are equal to the pressure of fluid under the lower pressure because both sides of the piston 22 are in communication with each other through the small hole 42. Therefore the piston 22 has exerted thereon an upwardly directed force equal in magnitude to the lower fluid pressure multiplied by the difference between pressure receiving areas of the upper and lower piston surfaces, which are different because of the difference in diameter of the upper and lower piston rods 25 and 26. The magnitude of that force is preselected to 'be sufficiently great to overcome the total weight of the drop body, 22, 26, 27, 28. The difference between the force acting on the piston and the total weight of the drop body serves effectively to press the annular land 40 against the annular seat 44 ensuring sealing therebetween.

The feeler 60 on the starting device 58 is raised by the drop body at the limit of its lift stroke, being moved upwardly from the FIG. 1 to the FIG. '2 posit on, the fluid therein being discharged through the solenoid valve 81. Limit switch 83 energizes solenoid valve 82, supplying pressure fluid to control valve 50 to cause the control valve 50 to open. This opening of the valve 50 permits the fluid under the higher pressure to fill the annular chamber 46. At that time, the fluid pressure will exert on the piston 22 a force tending to cause the latter to descend, but it is not sufficiently high to overcome the upwardly direced force as described above. his causes the piston 22 to remain at its uppermost position.

The solenoid valve 81 is then energized, for example, by manually closing switch 81b, to supply fluid under pressure to device 58 to move the feeler 60 to slightly depress the drop body 22, 26, 27, 28 against the aboye mentioned force acting on the annular land 40. Tue relative positions of the components at that instant are illustrated in FIG. 3. It is now assumed that this downwardly directed force is higher than the upwardly directed force of the drop body, and therefore serves to slightly depress the body.

As shown in FIG. 3, the pressure from the annular chamber 46 is applied to the entire area of the upper piston surface to cause the drop body to drop at a high speed. As the drop body descends, the fluid within the upper cylinder space 24 is progressively expanded thereby to decrease its pressure. In addition, a portion of the fluid within the upper cylinder space 24 flows into the lower cylinder space 25 through the small hole 42. The fluid in the lower cylinder space 25 flows into the lower pressure reservoir chamber 66. Eventually the drop body reaches the lower limit of its descending stroke whereupon it imparts an impulsive force to a workpiece to be forged while at the same time the drop body is deprived of its descending velocity thereby to stop instantly.

At a time at which the drop body has dropped to complete the forging operation, the solenoid valve 81 is instructed to be reset by the timer 81a, e.g. by the timer opening switch 81b. This causes the starting device 58 to return to its original position and permits the feeler 60 to be raised freely. When the drop body has returned to its Original raised position, the feeler 60 is raised by the action of the upwardly directed force exerted by the drop body. The limit switch 83 will open as soon as the drop body starts down, thus deenergizing solenoid valve 82 and closing control valve 50. When the drop body has returned to its original position, the switch 83 will automatically supply a signal to the solenoid valve 82 to open control valve 50. The apparatus is then ready for another cycle upon operation of switch 81b.

From the foregoing, it will be appreciated that the impulsive force for use in forging depends mainly upon the pressure and quantity of the fluid under the high pressure rather than upon the weight of the drop body. As previously described, the pressure and quantity of the fluid under the higher pressure remain unchanged and can readily be controlled. Therefore the forging energy can readily be held at its preselected magnitude.

FIG. 4 illustrates the position of the drop body as it just reaches its lowermost position in which it stops instantly. At the instant the drop body has stopped, the fluid pressure on the upper piston surface is not equal to that on the lower piston surface. However, as the upper and lower cylinder spaces 24 and 25 communicate with each other through the small hole 42, the difference between pressures in the two spaces gradually decreases and the pressure difference becomes zero after a short period of time. Therefore, the lower surface of the piston 22 having the greater pressure receiving area has an upwardly directed force applied thereto due to the difference of the pressure areas on the upper and lower piston surfaces, whereby the drop body is lifted until it returns to its initial position illustrated in FIG. 2, whereupon one cycle of operation is completed. Thereafter, the cycle of operation as described above is repeated until the forging operation is completed.

Referring now to FIG. 5, the same reference numerals designate components identical to those illustrated in FIG. 1. In FIG. 5, the hole 42 through the piston 22 is omitted, and a separate connecting pipe 78 is provided for connecting the upper cylinder space 24 with the lower cylinder space 25. More specifically, the connecting pipe 78 opens at one end through the upper end face of the upper cylinder space 24 and at the other end through the lower end portion of the lower cylinder space 25. It is noted that with the piston 22 in its lowermost position, the pipe 78 still communicates with the lower cylinder space 25. Preferably there is disposed in the pipe 28 a flow adjusting valve to adjust the flow of fluid through the latter to control the rate at which the pressure differential between the cylinder spaces decreases and the speed at which the drop body 22, 26, 27, 28 is lifted. Other parts are identical to those in FIG. 1. Therefore, the apparatus is operated in the same manner as previously described in conjunction with FIGS. 2 to 4 inclusive. If desired, the valve may be replaced by a suitable orifice. Alternatively, the valve may be omitted.

The invention has several advantages. For example, the use of a closed loop type fluid circulation system utilizing a fluid under high pressure leads to a minimum exhaust loss and a maximum speed of the drop body resulting in high speed forging. Further, the apparatus can be relatively small in size and yet provide a high forging energy. The high speed of the apparatus permits a workpiece to be in contact with the associated forging die for a minimum possible period of time. This together with the controllability of the capability of the apparatus enable a precise forging, and the decreases in the periods of time during which the drop body is lifted and the fluid under the high pressure fills the annular chamber ensures continuous forging, as will be readily understood from the foregoing description.

While the invention has been illustrated and described in conjunction with two embodiments thereof, it should be understood that various changes and modifications may be resorted to without departing from the spirit and scope of the invention.

What we claim is:

1. A high speed forging hammer apparatus comprising a vertical operating cylinder, a piston member vertically slidable within the cylinder member and dividing the interior of said cylinder member into an upper cylinder space and a lower cylinder space, an upper piston rod projecting from said piston member into the upper cylinder space, a lower piston rod projecting from said piston member into the lower cylinder member and further extending externally of the cylinder member, said upper piston rod being greater in diameter than said lower piston rod, a hammer tap connected on the lower end portion of said lower piston rod, said piston, said upper and lower piston rods, and said hammer tap forming a drop body, a reservoir including a higher pressure chamber having fluid under higher pressure contained therein and a lower pressure chamber having fluid under lower pressure contained therein, a first duct means connecting said upper cylinder space with said higher pressure reservoir chamber, a control valve disposed in said first duct means to control a flow of fluid under higher pressure into said upper cylinder Space, second duct means connecting said lower cylinder space with said lower pressure reservoir chamber, starting means responsive to the position of said piston member to actuate said control valve and also to give an initial movement to said piston member, and compressor means connected between said lower pressure reservoir chamber and higher pressure reservoir chamber for pressurizing fluid from said lower pressure reservoir chamber and feeding the pressurized fluid into said higher pressure reservoir chamber, the piston member having a small hole axially extending therethrough to place said upper cylinder space in communication with said lower cylinder space, and said higher pressure reservoir chamber, said first duct means, said upper cylinder space, said small hole in the piston member, said lower cylinder space, said second duct means, said lower pressure reservoir chamber and said compressor means forming a closed loop circuit.

2. A high speed forging hammer apparatus comprising a vertical operating cylinder member, a piston member vertically slidable within said cylinder member and dividing the interior of the cylinder member into an upper cylinder space and a lower cylinder space, an upper piston rod projecting from said piston member into th I upper cylinder space, a lower piston rod projecting from said piston member into the lower cylinder member and further extending externally of the cylinder member, said upper piston rod being greater in diameter than said lower piston rod, a hammer tap connected on the lower end portion of said lower piston rod, said piston, said upper and lower piston rods, and said ram forming a drop body, a reservoir includind a higher pressure chamber having fluid under higher pressure contained therein and a lower pressure chamber having fluid under lower pressure contained therein, a first duct means connecting said upper cylinder space with said higher pressure reservoir chamber, a control valve disposed in said first duct means to control a flow of fluid under higher pressure into said upper cylinder space, second duct means connecting said lower cylinder space with said lower pressure reservoir chamber, starting means responsive to the position of said piston member to actuate said control valve and also to give an initial movement to said piston member, compressor means connected between said lower pressure reservoir chamber and said higher pressure reservoir chamber for pressurizing fluid in said lower pressure reservoir chamber and feeding the pressurized fluid into said higher pressure reservoir chamber, and a connecting pipe connected at one end to the upper end surface of said upper cylinder space and at the other end to the lower portion of said lower cylinder space, said higher pressure reservoir chamber, said first duct means, said upper cylinder space, said connecting pipe, said lower cylinder space, said second duct means, said lower pressure reservoir chamber and said compressor means forming a closed loop circuit.

3. A high speed forging hammer apparatus as claimed in claim 2 wherein said conducting pipe has therein an adjusting valve to control a flow of fluid therethrough.

4. A high speed forging hammer apparatus comprising a vertical operating cylinder, a piston member vertically slidable within the cylinder member and dividing the interior of said cylinder member into an upper cylinder space and a lower cylinder space, an upper piston rod projecting from said piston member into the upper cylinder space, a lower piston rod projecting from said piston member into the lower cylinder member and further extending externally of the cylinder member, said upper piston rod being greater in diameter than said lower piston rod, a hammer tap connected on the lower end portion of said lower piston rod, said piston, said upper and lower piston rods, and said hammer tap forming a drop body, a closed pressure fluid circulating system including a reservoir including a higher pressure chamber having fluid under higher pressure contained therein and a lower pressure chamber having fluid under lower pressure contained therein, a pressure increasing means connected between said chambers, said upper cylinder space being connected with said higher pressure reservoir chamber and the lower cylinder space being connected with said lower pressure reservoir chamber, a control valve means coupled between said higher pressure reservoir chamber and said upper cylinder space for controlling flow of fluid under higher pressure into said upper cylinder space, starting means responsive to the position of said piston member to actuate said control valve and also to give an initial movement to said piston member, a constantly open conduit means between said upper and lower cylinder spaces placing said upper cylinder space in communication with said lower cylinder space, and said higher pressure reservoir chamber, said upper cylinder space, said open conduit means, said lower cylinder space, and said lower pressure reservoir chamber forming a closed loop circuit.

References Cited UNITED STATES PATENTS 513,601 1/1894 Teal 914l6 1,897,581 2/1933 McNab 9l416 2,742,879 3/ 1953 Kieser.

2,902,007 9/1959 Rockwell 91-401 2,954,755 10/ 1960 Pecchenino. 3,115,676 12/1963 Quartullo 91-416 PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R.

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