Abstract: A method for operating a mechanical press including an electric drive motor, a drive control for controlling the motor, a ram, a flywheel, a clutch and a member for translating rotational motion of the flywheel in a first rotation direction into a linear motion of the ram arranged to be lowered and raised along a linear path for operating the press to carry out a press production cycle. The press cycle includes a pressing part and one or more non-pressing parts. The press includes a second drive motor or actuator arranged connected to the ram and by providing a control output to the drive control, the speed of the second drive motor is made variable during at least one part of the press production cycle. The press may be reversed between production cycles. A press and system including such a press.

Abstract: A press machine includes a cushion shaft, a press shaft, a motor, and a motor control device. The cushion shaft is connected to a lower die. The press shaft is connected to an upper die and configured to press a workpiece between the upper die and the lower die in cooperation with the cushion shaft. The motor is configured to drive the upper die. The motor control device is configured to control the motor and includes a disturbance observer and an intrusion detector. The disturbance observer is configured to calculate an estimated disturbance value with respect to the motor based on a torque command and a motor velocity of the motor. The intrusion detector is configured to detect, based on the estimated disturbance value, a state of a foreign object between the press shaft and the cushion shaft.

Abstract: A control apparatus of a press machine in which a motor performance torque is fluctuated in accordance with a rotational angle of the rotating body in the case of rotating the motor at a fixed instruction speed. The control apparatus includes an angle detecting apparatus detecting a rotational angle of the rotating body, a torque determining apparatus determining a necessary motor torque in correspondence to a characteristic of the press machine on the basis of a value of the rotational angle input from the angle detecting apparatus, and a speed adjusting apparatus increasing the rotational instruction speed of the motor to a value more than the fixed instruction speed, at the rotational angle of the rotating body in which the necessary motor torque becomes smaller than a predetermined motor torque reference value.

Abstract: A large round baler equipped with moisture sensing apparatus and a bale scale to improve information useful in baling and using bales. Moisture sensing begins after the bale reaches a predetermined diameter. A history of bale weights is used to estimate how much tension to apply to a belt tensioner to achieve both a target bale weight and a target bale size.

Abstract: In a pneumatic compressor for the compression of waste, for example waste paper comprising a cylinder (1) with a piston (2), which via a piston rod (4) activates a compression plate (3), which is slidably mounted in a compression chamber (5) which has a top door (6) through which waste paper is thrown into the compressor, and a bottom door (7) through which a finished bale can be taken out, which compression takes place in a series of compression cycles, which each time is charged with a new portion of waste, until the waste can offer a counter pressure corresponding to the pressure which the piston (2) can exert at a pressure of 8 bars. In 80-90% of the compression cycles necessary for the compression of a bale, the piston (2) reaches its bottom position in the cylinder, and each time the pressure reaches a pressure of 8 bars in the cylinder (1).

Abstract: A slurry filtration system and apparatus with peripheral elements for conditioning a slurry prior to entry into a pressure filter (32) and the control of fluid and liquid introductions into the filter (32) to produce a desired filter cake or filtrate. The system includes a controller (16) for controlling the operation of the peripheral treatment for the introduction of coagulants, flocculants and polymers to treat or condition a slurry introduced into the filter (32) and the control of additional peripheral equipment for treatment of the slurry with liquid clearing or cake forming gas, steam, or drying or conditioning gas within the filter chamber (40) for the production of both filtrate and filter cake from the filter (32) to a form desired.

Abstract: In order to further develop overload protection devices for machine tools, the invention relates to an overload protection comprising a force input element and a force output element which are rigidly and non-positively interconnected by means of a positive connection and can be moved relative to one another when an overload protection is actuated. The overload protection devices are characterized by an emergency running gear; by means of which the force input element and the force output element are interconnected so as to be guided towards each other in a controlled manner when the overload protection is actuated.

Abstract: A servo press line operation control device includes a normal press operation control section, a normal transfer operation control section, an upward movement step delay determination section, a downstream-side transfer step delay correction control section, an upstream-side transfer step delay determination section, a slide downward movement step delay correction control section, and the like.

Abstract: A servo drive system of a press machine includes a ram, an operation shaft which vertically moves the ram, and a servo motor which operates as a power source of the ram and which generates ram pressure using a torque based on at least one speed-torque characteristic of the servo motor. The operation shaft is directly driven using the servo motor. The at least one speed-torque characteristic of the servo motor is set in a manner such that a motor torque of the servo motor at which a capacity of electric energy supplied by a servo amplifier is determined becomes the motor torque at which an optimal punching pattern of the ram is generated from a light load to a heavy load according to a type of workpiece to be worked by the press machine.

Abstract: A pressing apparatus using a motor, in which a driving device for fast feed, which lowers a upper die to a position immediately before pressing, and a motor for pressing, which performs a pressing operation, are used to cause the driving device for fast feed and the motor for pressing to operate cooperatively, and only one position detector, which detects a present position of a slider, is provided for a set of the driving device for fast feed and the motor for pressing. A lock device is provided so as to lock the slider and the screw shaft while the motor for pressing is operating for pressing a work piece.

Abstract: A control element for a press as well as a press with such a control element is described. The control element is used to position an upper tool of the press at, on or in a work piece to be processed, with the control element featuring at least one actuator by which an opposing moment or an opposing force is created on an operating hand of an operator, with the opposing moment or the opposing force being related to a current slide force by means of which the upper tool acts on the work piece. The press further includes a control unit for determining the current slide force, so that the control unit on the basis of the slide force determined outputs a control command to the control element by which the actuator of the control element is activated.

Abstract: A terminator assembly for a terminal crimping machine includes a drive member and a first ram member coupled to the drive member. The drive member moves the first ram member in a first direction toward a crimping zone of the terminal crimping machine, and a second direction away from the crimping zone of the terminal crimping machine. The terminator assembly also includes a second ram member movable with respect to the first ram member to control the crimp height of the terminal crimping machine. The second ram member includes a base portion configured to engage at least one of an applicator assembly and crimp-tooling. An adjusting mechanism is coupled to each of the first and second ram members. The adjusting mechanism is configured to adjust a relative position of the first ram member with respect to the second ram member. A motor is operatively coupled to a drive shaft, and the drive shaft engages the adjusting mechanism for driving the adjusting mechanism.

Abstract: In some embodiments, a compactor may include one or more of the following features: (a) a frame coupled to a base having side panels with a front portion, a side wall, and a rear portion, (b) a compaction plate assembly including a platen pivotally coupled to the side walls for rotation about a fixed axis, (c) a compaction plate driver coupled to a rear wall for driving the platen in a semicircular direction toward and away from a rear wall of a cart, (d) an electrical switch for preventing operation of the compaction plate driver when a door member coupled to the frame is ajar, and (e) a speaker for playing an audio message upon actuation of an electric motor.

Abstract: A simulation press having a main body and an actuator attached thereto. The actuator is substantially aligned with the main body. A first plate is coupled to the main body and a second plate is coupled to the actuator. Both plates are adapted to engage a workpiece so as to simulate various modes of deformation of an area or areas on the workpiece when the second plate is moved relative to the first plate. The simulation press further includes a drive controller for controlling operation of the actuator. The drive controller additionally responds to feedback from at least one feedback sensor included with the simulation press.

Abstract: The present disclosure concerns a jam detection and safety system for machines prone to jamming, such as a baler. In particular embodiments, the system is implemented in a horizontal baler having a shear bar and a hydraulic ram that advances material being baled past the shear bar into a compression chamber. The system includes a strain gage mounted on the shear bar and a controller that is electrically connected to the strain gage. The controller receives strain signals from the stage gage and compares the strain of the shear bar to a predetermined strain threshold corresponding to a jamming condition. If the strain exceeds the predetermined threshold, the controller automatically deactivates the ram, such as by disconnecting line power from the baler and/or by turning off the control power of the baler.

Abstract: A trash compactor designed for public use is powered by a photovoltaic cell array. This allows the trash compactor to be placed in locations where no power is available, but with frequent human traffic. The compaction feature allows the unit to be emptied less often than a typical trash container. The trash compactor can include a storage system to store power for compaction cycles. A removable bin allows easy removal of the compacted trash. The removable bin can include multiple chambers for different trash types.

Abstract: A servo drive system of a press machine has a pair of servo motors which can generate necessary ram pressure by compositing and using a torque based on the same speed-torque characteristics. The servo motors are symmetric with each other in a mirror image manner. The servo motors are opposed to each other at opposite ends of an operation shaft which vertically moves a ram. The servo motors are integrally operated, thereby directly driving the operation shaft.

Abstract: A slide position sensor includes: a link supporting member projecting from the slide toward the upright, a dual axis link member whose first end is rotatably supported and hung by the link supporting member, a plate rotatably supported and hung by a second end of the dual axis link member, a rack that is provided to the plate and extends in the hanging direction, a pinion that meshes with the rack and an encoder system that senses the rotation of the pinion.

Abstract: A device for applying an axial compressive force to a fluid contamination detection system comprising a cup joined by a frangible connection to a filter ring, the force being sufficient to break the frangible connection and collapse a portion of the ring into the cup without damaging the ring. The device includes a stop element and a platform and an actuating mechanism for reciprocally moving the platform relative to the stop element. In a first position, the distance between the platform and the stop element is greater than the axial length of the detection system when the cup and the filter ring of the funnel are connected to each other, and in a second position, the distance between the platform and the stop element is less than the axial length of the detection system when the cup and the filter ring of the funnel are connected to each other.

Abstract: A container having a compactor and bin for waste is disclosed permitting on-premises and remote monitoring of the system and collection is disclosed. The system can also detect non-complaint materials placed therein and act thereon. Methods are further disclosed for inventorying identification tags for tracking packages, merchandise and tags disposed of.

Abstract: A refuse compactor especially designed for use in fast-food restaurant environments includes a hydraulic pump driven by an electric motor for actuating a hydraulic ram to compress restaurant waste materials. The compactor includes a unique outer support structure that derives strength from the outer housing skins to support a compaction plate assembly. The compaction plate assembly maintains the platen inclined at a predetermined angle to the vertical when the platen is elevated and which forces the platen to a horizontal disposition during a downward compaction stroke. A motor operated closure member selectively blocks and unblocks a refuse-receiving opening formed in a front door of the compactor unit and with a motion detector controlling the opening and closing of the refuse entry door panel.

Abstract: A slide of a press machine is driven by composite thrust of thrust of an electric (servo) motor SM (via a screw/nut mechanism from the electric motor) and thrust of hydraulic cylinders SYL1, SYL2 to which pressure oil is supplied from a constant, high pressure source. A slide control device controls the electric motor SM and the hydraulic cylinders SYL1, SYL2, based on a slide position signal and a motor angular velocity signal, and at the same time, makes the hydraulic cylinder SYL1 work as a pump during a period when slide load is small, charging pressure oil to the constant, high pressure source by using the thrust transferred from the electric motor to the hydraulic cylinder SYL1 through the screw/nut mechanism and the slide.

Abstract: A slide of a press machine is driven by composite thrust of thrust of an electric (servo) motor SM (via a screw/nut mechanism from the electric motor) and thrust of hydraulic cylinders SYL1, SYL2 to which pressure oil is supplied from a constant, high pressure source. A slide control device controls the electric motor SM and the hydraulic cylinders SYL1, SYL2, based on a slide position signal and a motor angular velocity signal, and at the same time, makes the hydraulic cylinder SYL1 work as a pump during a period when slide load is small, charging pressure oil to the constant, high pressure source by using the thrust transferred from the electric motor to the hydraulic cylinder SYL1 through the screw/nut mechanism and the slide.

Abstract: A gyratory compactor apparatus is provided for interacting with a sample within a generally cylindrical mold having a flange. Such an apparatus comprises a frame defining an axis and an offsetable member engaged with the frame for engaging one end of the mold. The offsetable member is displaceable from the axis and is concurrently movable in an orbital motion thereabout. A pressure ram is movable along the axis and a mold-engaging device is engaged with the frame for receiving the mold such that the mold and frame axes are coaxial. The pressure ram is axially movable within the mold to apply a compaction pressure on the sample, and thereby maintains a portion of the mold at a gyration point along the frame axis. The mold-engaging device axially moves the mold into engagement with the offsetable member.

Abstract: A press drive unit and press drive method are provided which decrease the cycle time of a press to improve its productivity, enable use of small-sized, inexpensive presses and provide improved product quality. To this end, the press drive unit comprises a drive shaft coupled to a slide through a specified power transmission mechanism; a first drive system for rotationally driving a flywheel with a main motor and driving the drive shaft through a clutch disposed between the flywheel and the drive shaft; and a second drive system for driving the drive shaft at variable speed with a sub motor. Driving is carried out with the first and second drive systems in a formation zone, and driving is carried out with the second drive system alone in a non-formation zone.

Abstract: A fruit press, in particular a citrus fruit press, having the following features: the fruit press has a mounting stand and a driving and pressing unit; the driving and pressing unit is mounted pivotably on the mounting means.

Abstract: The present invention provides a linear motor mounted press machine that generate an optimum thrust for a press tonnage to perform different machining operations including one requiring a greater press tonnage and one requiring a high speed and a smaller press tonnage in an energy efficient manner. A linear motor mounted press machine includes a first linear motor 11, a second linear motor 12 that produces a thrust lower than or equivalent to that of the first linear motor 11, and a coupling switching mechanism 13 that releasably couples output shafts 30, 34 of the first and second linear motor 11, 12 together. A press tool 6 is driven forward and backward by the output shaft 34 of the second linear motor 12. Each of first and second linear motors 11, 12 is a unit linear motor assembly having a plurality of unit linear motors 15 arranged around a press working axis center P. The number of the unit linear motors 15 of the second linear motor 12 is the same as or smaller than that of the first linear motor 11.

Abstract: The invention relates to a round baling press having a baling press chamber and a door arranged in the rear section of the baling press chamber. The door is movable along a path between a closed position, in which the door extends along the back side of the baling press chamber, and an open position in which a completely formed bale can be ejected from the baling press chamber. The baling press further includes at least one sensor providing information on the position of the door. The sensor provides a signal value which contains information on the respective position of the door along its path of movement.

Abstract: A baler utilizing gas springs for controlling the movement of a loading door. Also disclosed is a baler for paper recycling having a control system responsive to switches and digital timers, and an electromagnetic interlock coupling a loading door and a chamber door, said control system including a programmable relay having outputs to motor starter, control valves, and electromagnetic interlock. A mode selection switch enables automatic, manual down, and manual up modes, the latter of which is used to eject a bale. The electromagnetic interlock performs multiple functions reducing the number of components needed in the system, improving reliability and reducing maintenance.

Abstract: A trash compactor designed for public use is powered by a photovoltaic cell array. This allows the trash compactor to be placed in locations where no power is available, but with frequent human traffic. The compaction feature allows the unit to be emptied less often than a typical trash container. The trash compactor can include a storage system to store power for compaction cycles. A removable bin allows easy removal of the compacted trash. The removable bin can include multiple chambers for different trash types.

Abstract: A mounting apparatus includes: a heater head for bonding a liquid crystal display and a flexible printed circuit board by thermocompression; a cylinder as a heater head driving means for driving heater head to compress the liquid crystal display and flexible printed circuit board by a prescribed load; and a control mechanism as a stretch amount controlling means for adjusting a load change per unit of time after the heater head starts compressing the flexible printed circuit board by the cylinder as well as a time at which a required load is attained to control the stretch amount of the flexible printed circuit board by thermocompression. Preferably, the mounting apparatus is provided with a mechanism which performs measurement after preliminary bonding and which performs regular bonding while controlling based on the obtained information.

Abstract: A simulation apparatus is provided comprising a fixed main body; a carriage associated with the main body for movement relative to the main body; a first device coupled to the fixed main body for engaging a workpiece; a second device coupled to the carriage for movement with the carriage and for engaging the workpiece; at least one motor apparatus coupled to the fixed main body and the carriage for effecting movement of the carriage and the second device relative to the main body such that a tensile load is applied to the workpiece; sensor apparatus comprising at least one force sensor for sensing the tensile load applied to the workpiece during the movement of the second device; and a drive controller.

Abstract: The present invention provides a motor driven link press which enables working with a heavy press load and also enables a working cycle time to be improved even when a motor with a relatively low output power is used and which can be properly controlled easily. A motor driven link press comprises a link mechanism 1 that converts a rotating operation into a linear operation and a ram 6 that elevates and lowers for press working on the basis of this linear operation. The link mechanism 1 comprises a crank member 2 having a crank shaft 3 and an eccentric shaft portion 4, a pivoting link 5, a connecting rod 7, and a restraining link 8. The pivoting link 5 has a first to third connecting portions P1 to P3 and is connected to the eccentric shaft portion 4 of the crank member 2 using the connecting portion P1. The connecting rod 7 is connected to the second connecting portion P2 and the ram 6.

Abstract: A method for inducing strain on a workpiece includes the step of providing a testing apparatus having a first set of teeth and a second set of teeth. The workpiece is placed adjacent to the first or second set of teeth. The second set of teeth is disposed on a movable carriage which linearly reciprocates thereby allowing the first and the second sets of teeth to engage and disengage each other. A commanded position by time is provided to the carriage while the actual position by time of the carriage is measured. The first set of teeth are in communication with at least one load cell such that when the first set of teeth engage the second set of teeth, the load applied by the carriage is measured. The actual position by time data and the load data are manipulated to produce vast information pertaining to the workpiece.

Abstract: A method and a briquetting press for briquetting metal chips, wherein stable briquettes/pressed component are produced. The actual length (Lact) of the pressed component is obtained by applying pressure (Pmax/Preq) using at least one pressing ram (1, 2) and measuring the length with a measuring device (5, 6). The measured value is compared to a desired nominal value (Lnom) and a difference value (?) is subsequently determined.

Abstract: A double action oil hydraulic press is provided having a main cylinder for actuating a slide and a lower part forming cylinder for actuating a lower part forming unit, wherein the operations of the cylinders are controlled through the combined control of the rotation of an oil hydraulic pump of a power unit and servo valves whereby the amount of operation oil that must be used is reduced.

Abstract: A refuse compactor especially designed for use in fast-food restaurant environments includes a hydraulic pump driven by an electric motor for actuating a hydraulic ram to compress restaurant waste materials. The compactor includes a unique compaction plate assembly that maintains the platen inclined at a predetermined angle to the vertical when the platen is elevated and which forces the platen to a horizontal disposition during a downward compaction stroke. A motor operated closure member selectively blocks and unblocks a refuse-receiving opening formed in a front door of the compactor unit and with a motion detector controlling the opening and closing of the refuse entry door panel.

Abstract: A rod pressure holding instruction section controls a servo motor to rotate a two-way pump in a counter direction, and to supply hydraulic oil, with pressure which does not exceed pressure from a weight of a ram, to a two-way pump-side piping, increasing pressure. A difference between pressure in a rod-side cylinder chamber-side piping of a speed switching valve and pressure in a two-way pump-side piping of the speed switching valve is decreased, thereby decreasing an impact generated when switching the speed switching valve and stopping the ram at a predetermined position.

Abstract: A simulation press is provided comprising a fixed main body; a carriage associated with the main body for movement relative to the main body; a first plate coupled to the fixed main body and being adapted to engage a workpiece; and a second plate coupled to the carriage for movement with the carriage. The second plate is also adapted to engage the workpiece. One or more motor apparatus are coupled to the fixed main body and the carriage for effecting movement of the carriage relative to the main body. A drive controller is coupled to the motor apparatus for controlling the operation of the motor apparatus in response to feedback from one or more feedback sensors so as to cause the second plate to move relative to the first plate such that the first and second plates engage at least one point site on the workpiece so as to simulate compression loading of a point site on a workpiece in a nip type process.

Abstract: A simulation press is provided comprising a fixed main body; a carriage associated with the main body for movement relative to the main body; a first plate coupled to the fixed main body and being adapted to engage a workpiece; and a second plate coupled to the carriage for movement with the carriage. The second plate is also adapted to engage the workpiece. One or more motor apparatus are coupled to the fixed main body and the carriage for effecting movement of the carriage relative to the main body. A drive controller is coupled to the motor apparatus for controlling the operation of the motor apparatus in response to feedback from one or more feedback sensors so as to cause the second plate to move relative to the first plate such that the first and second plates engage the workpiece and simulate a ring rolling operation on the workpiece.

Abstract: A method and a briquetting press for briquetting metal chips wherein stable briquettes/pressed components are produced. The actual length (Lact) of the pressed component is obtained by applying pressure (Pmax/Preq) using at least one pressing ram (1,2) and measuring the length with a measuring device (5, 6). The measured value is compared to a desired nominal value (Lnom) and a difference value (&Dgr;) is subsequently determined.

Abstract: An auto-positioning inching control for a mechanical press allows a press operator to select one of a plurality of preset slide stop zones in which the slide may be stopped. A programmable logic controller is utilized to compute values of clutch dropout which will operatively position the slide in one of a plurality of preselected slide stop zones. An additional inching mechanism may be utilized for further movement of the slide within the preselected slide stop zone.

Abstract: A compressing machine includes a press unit 12 for compressing a concentrated sludge within a squeezing chamber to provide a briquette B, and a press control means 13 for controlling the press unit 12. The press control means 13 includes a parameter and compressing speed setting means 26, a parameter measuring means 28, and a compressing speed control means 27. The parameter and compressing speed setting means 26 is a means in which a relation between a predetermined parameter that may affect compression performed by the press unit 12, and a compressing speed of the press unit 12. The predetermined parameter may include a coolant temperature, ambient temperature or a coolant content and others. The parameter measuring means 28 is a means for measuring the predetermined parameter.

Abstract: To provide a punch press which can realize the high hit rate and the energy saving in the punch drive. A plate material transfer control means 32 and a ram axis control means 33 controlled synchronously are provided. The plate material is started to transfer when a punch tool 6 reaches a pullout height HH2 after punching and it is arranged to come to a height HH1 which is likely to contact with the plate material when completing transferring the plate material. The ram axis control means 33 rotates a servomotor 19 in one direction. Moreover, the ram axis control means 33 controls in a motor speed pattern VP based on the distance of transferring the plate material after the punch tool 6 goes up from the pullout height HH2 and the servomotor 19 is prevented from stopping as possible. The motor speed pattern VP is made to be a trapezoid pattern that the acceleration is constant.

Abstract: A feedback control system for use in a press machine is adapted to monitor and adjust the clearance between the gib and slide. A connection bolt provides a connection between the gib and frame upright. A thermal applicator selectively heats and/or cools the connection bolt to induce a controlled deformation of the bolt, namely, an expansion and/or contraction, respectively. In one form, a heat-induced elongation of the bolt along its longitudinal dimension actuates a corresponding displacement of the gib towards the slide to regulate the spatial relationship therebetween. A sensor provides a measure of any possible clearance between the gib and slide. The clearance measurement is compared to allowable reference clearance data. A controller controls the heating and/or cooling action in accordance with the comparison results, thereby controllably moving the gib. The gib may be selectively displaced to optionally effectuate a partial or full close-out of the existing clearance.

Abstract: The invention relates to a controller for a hydraulic press, comprising a pressing cylinder (1), a reservoir (2), a valve group (3), a pressure medium reservoir (7) and a hydraulic pump (6), connected together by means of a cylinder line (4), a reservoir line (5) and a tank line (8). According to the invention, a pressure converter (9) is arranged on the valve group (3), which may operate as a pressure amplifier or pressure reducer. The particular mode of action of said controller is achieved whereby the valve group (3) comprises a pre-press valve (11), a low-pressure chamber outlet valve (12), a low-pressure chamber inlet valve (13), a main press valve (14), a closing valve (15), a pressure release valve (16) and a 3-way valve (17), which may be operated by a particular control sequence. Said invention is applicable in hydraulic presses and of particular advantage in presses for the forming of ceramic pieces such as tiles.

Abstract: A screw press apparatus has frames, a screw shaft, an outside tube, a cylindrical screen, a screw blade, a supply pipe, and a cleaning pipe. The screen is fixed between the frames to the outside tube, and has a plurality of fine holes and covers the screw shaft. The screw shaft and the screen define a cylindrical space continuously extending from an upstream region to a downstream region. Raw liquid is fed from the supply pipe via an opening of the screw shaft to the upstream region of the cylindrical space. The cleaning pipe ejects cleaning water onto the screen. Sizes of the fine holes of the screen decrease gradually from the upstream region towards the downstream region.

Abstract: A method and apparatus for crushing and sorting cans to collect waste cans in an optimal weight-to-volume ratio.

Abstract: Aa process for operating a press arrangement involves a press slide and at least one workpiece transport device that are electromechanically driven and electrically supplied by a supply and feedback device having at least one input and at least one output. In the event of a voltage drop at the input of the supply and feedback device, the current intensity at the input of the supply and feedback device is increased.

Abstract: A screw press which can ensure the positional precision of the ram when the rotation amount of the press motor does not directly translate into the position of the ram because there is other machinery, such as a decelerator and the like, present between the motor (servo motor) and the screw mechanism, has a construction in which a position detection sensor, which detects the position of the ram, is provided, and the position of the ram is controlled by the output from this sensor.