JPS6362353B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electric impact driving machine.
This article relates to a method of driving a tensioning tool in a device such as a tool.

Low-energy, electrically powered driving machines are common and are used to drive small nails, clasps, and tighten and loosen nuts. Used to attach deformable fasteners such as brass or copper rivets. However, at present,
High-energy driving machines, at least the hand-held version, were operated by compressed air. This compressed air type driving machine has a number of drawbacks. That is, large hoses are required and also a large volume air source that is not practically movable. Furthermore,
This kind of pneumatic equipment requires equipment such as pressure control equipment, lubricating oil equipment, filters, etc., making the equipment complex, difficult to handle, and expensive.

Although high-energy, hand-held, electrically powered driving tools are certainly desired,
There are still many unresolved issues. For example, driving a 16 penny nail (an 8.3 cm (3.25 inch) long nail) into medium-hard wood with the nail head just above the surface of the wood requires approximately 453.6 kg (1000 kg). lb)
The peak force required can be easily determined using an arbor press and instrumentation. Since the nail provides an equal reaction force on the driver, and the operator is unlikely to be able to resist the peak force of 1000 lbs, the lower speed of the driver will reduce the force. would not work well, since the nail would be pushed back from the piece of work rather than being pushed into the wood. Therefore, the time required to drive the nail and the volume of the driver are of paramount importance. design parameters
This is especially true when the parameters (parameters) have a high demand for recoilless operation.

For example, the amount of potential energy that must be stored in mechanisms and systems of the type that are required to transfer energy to a workpiece within a short time period, tasked with doing essentially recoilless work. For the purpose of calculating , other actual parameters such as tool capacity and contact speed can be chosen for the tool. Once this is done, the above calculations reveal the following. That is, a significant energy storage capacity combined with a very fast and sufficient force transmission mechanism is absolutely necessary. Moreover, this calculation shows that it is totally useless to use conventional things like electromagnets to solve the problem. This is because an electromagnet unit that can generate the average required power in the short time required to perform the recoilless work described above is too large and heavy to be practical. (Even if you ignore the price point)
It is from.

The idea of a flywheel comes to mind as a small, lightweight mechanism that can store high energy. Unfortunately, a flywheel is a small, lightweight mechanism that can store high amounts of energy, but unfortunately, a flywheel is a high-speed rotating system that is prone to undesirable precession moments. ) was large, making it unsuitable for hand-held tools and making it difficult to put it into practical use. Moreover, the tools held in this hand must have a certain degree of precision. The problem presented to workers in managing these forces is that with a single flywheel tool, the problem is not fatal.
This means that it is a very dangerous machine. This danger occurs when the machine has fasteners, such as nails, that can be fired at high velocity.
This is because there are considerable difficulties in trying to control this firing.

In accordance with the present invention, a high-energy, electrically-driven manual drive system capable of producing approximately 75 horsepower to drive the 8.3 cm (3.25 inch) nail in a short period of time on the order of a few thousandths of a second is provided. We have actually created a type of driving machine that can be used in this way. In fact, a small, low horsepower electric motor is sufficient to provide the power at more than one cycle per second.

Not one, but a pair (two) of substantially similar flywheels that rotate in opposite directions can store the required energy, and the pair of flywheels can properly interact with each other. They are compatible and are designed to eliminate troublesome precession moments that occur when the flywheel rotates at high speeds. These identical flywheels are rotated so that one of them engages a friction ram located between the pair of flywheels in relation to the other flywheel, and the ram is forced to rotate within a short period of time on the order of a few thousandths of a second. To,
This constitutes an efficient high-speed power application mechanism that is capable of applying considerable driving force. Thus, a clutch made in this manner does not require synchronous engagement and, when well designed, will not slip.

A mechanical interlock is provided, i.e., holds the tool firmly against the work piece (the object into which the nail is being driven) when the trigger is pulled to engage the clutch. The protruding part of the tool makes it safe for work, and even if there is an accident in which the tool is dropped, the nail will not explode. Although a motor speed controller may not necessarily be exactly a safety device, it does provide the operator with the ability to reduce the ram's energy to an appropriate level for the workpiece. It provides the means to do so.

Ordinary household electrical current is sufficient to power the tool, and in practice the power requirement can easily be supplied by batteries or a small self-contained generator. This is especially true for cycles with low power demands.
The problem is not so much the energy consumption during the minimum drive cycle as with small, low-horsepower motors, but rather the time required to speed up the flywheel drive motor to the required speed. That turns out to be a problem.

When the driving machine of the present invention is designed as a nailing machine, it can be used as is without any modification.
It is suitable for accepting commercial nail strips or belts. This also applies to fasteners (other than nails) such as rivets or similarly packaged fasteners. Generally, this type is housed in a spring-loaded magazine of conventional design.

It is thus a first object of the present invention to provide a method of driving a fastening tool that can reasonably achieve the advantages of a new, high-energy, hand-held, electric driving machine. It's about trying to get it.

A second object of the invention is to achieve a method of driving a tensioning device which utilizes the principle of a high-speed flywheel and which makes it possible to utilize an energy storage medium in the absence of precession moments.

Another object of the invention is to use a matched pair of counter-rotating flywheels as a medium of energy transfer, whereby the latent energy stored therein is transferred almost instantaneously to the rams. The purpose of the present invention is to achieve a method for driving a tensioning device.

Another object of the invention is that the ram is actuated by a self-locking, effectively non-slip, high power friction clutch, thereby eliminating the need for synchronous engagement between toothed clutches. This is what we are trying to accomplish in terms of how to drive a brace.

An additional object of the invention is an electrically operated, hand-held tool based on the principle of double counter-rotating flywheels, which is suitable for use in nailing, riveting, and fastening machines. Applicable to stamping machines, chisel machines and similar tools, the work cycle of which is based on the high speed striking of a retractable ram, is economically achievable. I'm trying to find a way to drive the fixture.

Other objects of the invention will become apparent to some extent from the description below.

Before giving a detailed description of the embodiment of the nail driving machine (indicated by the reference numeral 10) of the present invention, a brief description of the most important elements and parameters of the tool will be given with respect to the principle explanatory diagram of FIG. Some of these are quite important. I shall first describe a simple experiment, combined with a detailed mathematical analysis, in order to obtain an idea of the force which must be produced by the instrument, and the time required to exhaust this force. , would be good to help you understand.

Below is a description of the mathematical analysis and experiment.

The peak force required to drive a 16 penny nail 8.3 cm (3.25 inches) long into a piece of medium-hard wood without the head of the nail protruding from the surface of the piece of wood is approximately 453.6 kg (1000 lb). ) was determined by an experiment using a simple arbor press.
Furthermore, the graph showing the relationship between the rate of nail penetration into the wood piece and the applied force is approximately linear up to the aforementioned 1000 pounds (453.6 kilograms). Therefore, the total energy consumed can be expressed by the following formula.

Equation (1)...E ₀ = ∫ ^L _p FdL125 ft-lb (17.3Kg・m) During nail driving work, the nail applies equal reaction force to the nailer or driver, so the mass of the nail and driver is The amount of time it takes to drive is a major consideration.

Assuming a screwdriver weight of 4.536 kg (10 lbs), which is a reasonable weight for a hand-held tool, and assuming a speed of contact when driving a nail of 152.4 cm/sec (5 ft/sec), The time for insertion into the wood is defined by the following equation (2). F here
Let (t) be the time-varying force applied to the wood by the nail.

Formula (2)...F(t)=MA=Mdv/dt However, M is the mass of the driver.

In equation (4), t _d is the time required to drive the nail.

Therefore, integrating equation (3)...F(t)/Mdt=dv, equation (4)...1/M∫ ^td _p F(t)dt=∫ ^Vf _Vi dv However, Vi is the nail driving speed of the tool, As previously determined, Vf is the final velocity of the same formula (5)...F(t) = 453.6 (t/t _d ) Kg [F(t) = 1000 (t/t _d ) pounds] (453.6Kg) From formula (4) to formula (6)…453.6t _d /2M = Vf−Vi [1000t _d /2M=Vf−Vi] When t _d is calculated from formula (6), formula (7)…t _d = 2M (Vf -Vi)/453.6 [t _d = 2M (Vf - Vi)/1000] Here, substitute the value assuming the nail driving speed to be 152.4 cm/sec (5 feet/sec), and set the final velocity to zero. , when the mass M is 10/32, the following formula is obtained.

Equation (8)...t _d = 2 (10/32) (5) / 100 = 0.003 seconds From this equation, using a tool weighing 4.536 Kg (10 pounds), with an initial speed of 152.4 cm/s (5 feet/s) Assuming recoilless operation (therefore, Vf = 0), it can be seen that it takes 0.003 seconds to drive the nail.

The average power value required during the working time t _d (time required to drive the nail) is determined by the following equation.

Equation (9)...Pave=125/550×0.003=75 horsepower From the above calculation, the following can be understood. That is, the tool must have a considerable energy storage capacity, and furthermore, the tool must have a considerable energy storage capacity.
This means that it must be able to be released within an extremely short period of time, on the order of seconds.

Now, assuming that a flywheel is employed in this energy storage mechanism, with a diameter of 7.62 cm (3 inches) and a rotational speed of ω, a meaningful comparison can be made between the peripheral speed of the flywheel and the driving speed of the nail, and Between the energy of the flywheel and the required energy,
can get.

Assuming that a 7.62 cm (3 inch) nail is driven in 0.003 seconds, this speed is calculated by the formula (10)...7.62/0.03 = 25.4 m/sec A flywheel with a diameter of 7.62 cm (3 inch) is driven at 2.54 m/sec.
Assuming that it rotates at a peripheral speed of 1000 inches/second, the rotational angular velocity is expressed by the formula (11)... ω = 1000/1.5 = 666 radian/second = 106 revolutions/second = 6366 r.pm This 6366 r.pm This speed is an appropriate speed and can be increased as necessary.

The energy of the flywheel is expressed by equation (12)...E=0.5Iω ² However, I is the rotational inertia value of the flywheel.

For a solid disk with a diameter of 7.62 cm (3 inches), its inertia value is expressed by the following formula: Equation (13)...I = 0.5 mr ^2For example, if the flywheel is made of brass and the diameter is 2.54 cm.
(1 inch), its mass M is calculated using the formula (14)...M=w/g=(535/1728)(9)(1)/32 = 0.0684 lb・^sec2 /foot (0.102Kg・sec ²
/m) Substituting equation (13), equation (15)...I = 0.5 (0.0684) (1.5/12) ² = 5.34 x 10 ^-4 pound-feet- ^second2 (1.02 x 10 ^-5 Kg-m-second ² ) Here, using ω = 666 radians/second, the energy is expressed by the formula (16)...E = 0.5 (5.34 × 10 ^-4 ) (666) ² = 118.43 foot pounds (16.4 Kg · m) (about 161 Joules) ) We mentioned earlier that we assumed that approximately 125 foot pounds (17.3 kg m) of energy is required to drive an 8.3 cm (3.25 inch) nail into medium-hard wood to the nail head. Diameter 7.62cm (3 inches) Thickness
7000 r.p. with a 2.54 cm (1 inch) brass flywheel.
m. has sufficient energy and circumferential speed to meet the requirements of the high-energy nail driving machine mentioned above.

However, as long as such a tool is held in the hand, it has a significant rotational moment. This rotational moment is due to rotation about an axis perpendicular to the spin axis of the flywheel. The magnitude of this moment is calculated as follows.

Equation (17)...Mp=IΩω Where, Mp is the precession moment acting on the nail driving machine, I is the inertia of the flywheel for the number of nails driven, ω is the rotational angular velocity of the flywheel, and Ω is the number of nails driven by the worker. Let it be the rotational angular velocity at which the loading machine attempts to rotate.

As an example, if a worker has a nail driver with the flywheel parameters described above and attempts to rotate the nail driver 180 times in 0.1 seconds, the number of nails caused by the gyroscope rotation The precession moment of the driving machine is calculated using the following formula.

Equation (18)...π radian/0.1 sec = 31.4 radian/sec Equation (19)...Mp = (31.4 radian/sec) × (5.34 × 10 ^-4 lb-ft- ^sec2 ) × (666 radian/sec) = 11.2 foot pounds (1.55 kg meters) This 1.55 kg meters is a large torque, making it extremely difficult for the operator to position the nail driver in the desired direction.

Therefore, in order to eliminate possible precession moments in the gripping tools, which have to be carefully and precisely positioned relative to the workpiece, two tools rotating at the same speed in mutually opposite directions about a horizontal axis are used. It is necessary to provide a functionally identical flywheel.
In accordance with the teachings of the present invention, it has been realized that there are many other parameters, more or less critical, to be recombined.

One of its most important parameters is that the ram element 12 is sandwiched between a pair of counter-rotating flywheels 14 and 15, and by these pair of flywheels the work piece shown in FIG. On the other hand, the entire working stroke of the ram, such as being driven forward, must occur in a very short period of time, a few thousandths of a second, in order to avoid any slipping or shearing of the tool. It is in.

In other words, if the tool were to be used to drive a 16 penny nail, during the brief 0.003 seconds that the ram was engaged with the nail, approximately
It is necessary to provide a tremendous force of 453.6 kg (1000 lbs).

Although drive communication between a pair of flywheels and the ram means could be accomplished in many ways, the only practical method employed requires synchronous engagement of a rack and pinion, etc. This method uses frictional force that does not Additionally, some type of clutch may be applied to momentarily engage the ram with a flywheel already undergoing rotation, but with the desired rotational movement of the flywheel in order to keep the flywheel engaged with the ram. It is impossible to drive the ram in a few thousandths of a second at speeds as high as .

Such a clutch can move both of a pair of flywheels toward and away from each other to engage and disengage them, or alternatively can move one movable flywheel to engage a ram while the other is in a fixed position. The flywheel can be moved relative to the flywheel and pressed against the side of the other fixed flywheel. Of these two modes of operation, the latter is preferred. This is because, according to the previously described mode of operation, if the ram means floats between two relatively movable flywheels, then for each actuation both flywheels are activated rather than simultaneously. This is because one flywheel approaches the ram before the other flywheel. When this happens, an excessively large acting force is created that exceeds equilibrium, causing one of the pair of flywheels to bend the other. As is clear, the ram engagement force in this case is three times the amount of force required to drive and actuate the nail, which is approximately 453.6 kg (1000 lb), resulting in a magnitude of approximately 1360.8 kg (3000 lb). Become.
Therefore, it becomes extremely difficult to properly design and engineer a deformable flywheel attachment mechanism.

Furthermore, the path of the forward movement or working stroke of the ram can be on either side of the guideway and cannot be determined if one flywheel moves in advance of the other during a particular drive.

In order to solve this inconvenient problem, one flywheel is arranged to be rotatable about a fixed spin axis, and a clutch is attached to the other flywheel so that when the flywheel is driven, a clutch is attached between the two flywheels. The preferred method is to be operable to reduce the spacing between the two.

As mentioned above, it is certainly possible to displace one movable flywheel towards the other stationary flywheel along a line perpendicular to the direction of movement of the ram toward its extended position, but the ram engagement Disadvantageous problems are posed because the resultant force is approximately three times as large as the maximum working force of the ram. However, a sufficient ram gripping force may be obtained by swinging one of the movable flywheels into engagement around a pivot axis located behind the spin axis. Understood.

The movable flywheel rotates rearwardly when the surface of the movable flywheel engages the surface of the ram means located adjacent thereto, forcing the ram means against the surface of the stationary flywheel, thereby causing the movable flywheel to rotate against the ram. increase the pressure exerted by the The action of such a flywheel upon engagement with the ram surface generates a ram gripping force of the required magnitude, and even if the ram gripping force is so great that it exceeds three times the maximum driving force of the ram. can occur quickly and easily.

The theoretical arcuate path of the spin axis of the movable flywheel lies in a plane through the pivot axis perpendicular to the direction of movement of the ram toward the extended position. Once the spin axis crosses behind this plane, the clutch acts to loosen its grip on the ram, thus breaking drive communication.

Therefore, in order to completely prevent wear on the engaging members, the spin axis of the precisely movable flywheel should be kept in a position that does not reach a point beyond the said plane. This is a significant problem that can be solved according to the teachings of the present invention.

As shown diagrammatically in FIG. 1, the acting force driving the ram element upward is expressed by the following equation:

Equation (20)...Fd=2FnKf where Fn is the value of the normal acting force between the flywheel and the surface of the ram means, and Kf is the friction coefficient between the ram element and the flywheel.

Further, as shown in FIG. 1, the downward acting force applied to the flywheel 16, which can be arcuate, is expressed by the following equation.

Formula (21)...Fu=FnKf The following equation can be derived from geometric theory.

Equation (22)...Fn=Fu/TanΘ where Θ is the distance between the first plane defined by the spin and pivot axes of the arcuately movable flywheel and the movement of the ram means 12 towards the extended position. This is the value of the acute angle formed by the intersection with the second plane perpendicular to the direction.

By substituting the above equation (21) into equation (22) and simplifying it, the following equation is obtained.

Equation (23)...TanΘ=Kf From the above equation, slip is a critical phenomenon that must never be allowed for all practical purposes, and if the relationship Kf≧tanΘ exists. It will be appreciated that slippage may be avoided during the engagement of the flywheel and the ram means. It is straightforward to select the values of the angle Θ and the coefficient of friction Kf such that the above critical relationship holds true.

The flywheel should be cylindrical and the engagement surface of the ram means should be flat so that both parts contact each other along a tangent to the eye parallel to the spin axis. Other complementary surfaces are unnecessary since points on the surface at different distances from the spin axis have different magnitudes of circumferential velocity, which inevitably leads to the phenomenon of slip. be.

Before providing a detailed description of the embodiment as a nail gun, some other features will be discussed below.

First, the size of the motor is considered to suit the desired work cycle. As mentioned above, the average power consumption required to drive a 16 penny nail until the head is flush with the surface of the work piece is approximately
It has 75 horsepower. Since energy is stored in the flywheel, the actual motor drive power required to drive the flywheel can be from 0 to 75 horsepower depending on the desired work cycle. If the motor work cycle is selected at a rate of 5 operations per second and friction is ignored, the desired motor drive force is:

Equation (24)...Preq = 75 (5 x 0.003) / (1) = 1.125 (horsepower) In other words, the motor driving force of 1.125 horsepower is the power of the flywheel at a rate of 5 operations per second. Able to maintain appropriate movement speed. As is clear, the motor described above has an excessive work cycle from a practical point of view, and even a small horsepower electric motor may be satisfactorily applied. Furthermore, the amount of energy consumed for each operation is such that the stored power is adequate to energize the motor, considering the amount of work done in a few hours.

Excessive ram biasing energy is disadvantageous, so it is preferable to adjust such energy accordingly. One of the energy adjustment methods is the 12th
Speed control means 18 for one or more motors, only one of which is shown schematically in the figure.
achieved by. The various positions of control knob 20 may be determined by a scale 22 shown in FIG. The scale 22 is set according to the size of the nail, for example.

A slight excess amount of energy is usually required, since a sufficient amount of energy should be applied to the ram means to ensure adequate consumption of work in the ram means. However, in order to avoid damage to the work piece due to the presence of this excessive amount of energy, the ram means is used to provide some degree of damage to the work piece without denting, gouging, drilling, etc. Preferably, means are provided to encourage the consumption of energy.
As such a means, the energy absorbing cushion 2
4 may be arranged on the protruding piece 26 at the forward end of the nozzle 28 to serve to absorb excess energy remaining in the ram means near the end of the working stroke. However, when the ram means is driven by a flywheel, the use of such a cushion is unnecessary.

Therefore, the length of the ram means is determined in relation to the position of the flywheel behind the lug so that the ram means enters driving engagement with the flywheel prior to the end of the working stroke or the beginning of the actuation of the cushion 24. It is preferable to break the relationship (see Figure 7).
This of course means that the coupling does not absorb the energy imparted directly to the ram means by the flywheel at the end of its working stroke;
This means that only the remaining energy needs to be absorbed. Obviously, the lighter the ram means, the lower the amount of energy remaining at the end of the working stroke.

The ram means advances forward past the flywheel to disengage it, but at least when drive communication exists between both members, the clutch re-opens the gap between the pair of flywheels; A tension spring 30 connected to the ram means is operable to send the ram back past the pair of flywheels to complete its working stroke. In the particular embodiment shown, the clutch drive means comprises a projecting piece 26 and a fixed link 32, the projecting piece 26 being mounted for retractable movement relative to the nozzle 28, and the fixed link 32 operatively connects the projecting piece 26 to a shaft-mounted frame 34 that supports the flywheel 16 movable in an arc. When the projecting piece 26 is moved backward toward the retracted position and pressed against the workpiece W as shown in FIG. It acts to swing rearward to engage in a driving relationship with.

Once the movable flywheel engages the ram means, the ram means disengages from the flywheel, even if it is possible to return the lug to the extended position during the few thousandths of a second required for the operating stroke. cannot be released until This may be accomplished automatically by means of a clutch release means connected to bias the frame 34, which is normally axle-mounted, in a direction that increases the spacing between the pair of flywheels. In the illustrated embodiment, the clutch release means comprises a compression spring 36 which acts to bias the retractable lug 26 toward the extended position. Thus, before such clutch release means are activated, the biasing force on the lug should be such that it exceeds the retraction force exerted on it by the work piece W. In practice, as soon as the ram means has completed its working stroke, the operator disengages the projecting piece from the work piece, thus activating the clutch release means to widen the spacing between the pair of flywheels and to release the spring 30. Action can cause the ram means to retract.

FIG. 2 shows a perspective view of an embodiment (10) of the nailing machine, the case or housing of which part is formed by the nozzle 28 designated by the reference numeral 40. Immediately behind the nozzle 28 a so-called flywheel 42 is provided. Inside this flywheel chamber 42, a pair of identical electric motors 4 are installed.
4, a movable shaft-mounted frame 34 for attaching one of the pair of electric motors, and a fixing member 46 for attaching the other one.

An upper rim 48 of the handle 50 extends rearwardly of the flywheel as an integral part of the housing longitudinally aligned with the nozzle. The upper rim 48 of this handle is hollow and suitable for accommodating the ram element 12 in the retracted position (see FIGS. 5 and 6).

In the illustrated embodiment, a control knob 20 of the speed control means 18 is arranged on a wall 52 behind the handle 50, located along a scale 22 provided according to nail size, etc. The handle 50 is
The overall C-shaped configuration is found in many electrically driven, hand-held tools. The handle 50 also supports a trigger 54 and a line cord portion 56 suitable for connection to a power source when the self-storing power source is not in use.

As shown, the case 40 is comprised of a pair of cast halves bolted together and has a removable movable cover 58.

Additionally, the illustrated embodiment includes a fastener 62, such as a nail.
An opening 60 is provided to allow the ram to be fed into the path of the advancing ram means 12 (FIG. 7,
(See Figures 8 and 9). A magazine or fastener housing 64 of conventional design is used to guide a commercially available belt nail into an opening 60 in the side of the nozzle.

The third part showing in detail the internal structure of the tool according to the invention
As can be seen with reference to FIGS. 7-7, a fixed end plate 66 is located at the bottom of the flywheel compartment 42;
This fixed end plate 66 is connected to the shaft 70F of the fixed electric motor 44F.
It supports a bearing 68 for. upright wall 7
2 divides the flywheel into two electric motors 74 and 76. A horizontal wall 78 integrally formed with the wall 72 defines two motor compartments 74 and 76.
is separated from the flywheel compartment 80. In the drawing, this horizontal wall 78 is shown supported on a scaffold 82 inside the flywheel compartment. A pair of additional bearings 68 are placed in fixed positions in one half of the flywheel, one in a groove in the top of the horizontal wall and the other in a groove in the scaffolding.

The flywheel 14, which is fixed in position, is attached to a motor shaft 70F that projects from the motor chamber 74 into the flywheel chamber. Thus, the stationary electric motor 44F and the flywheel 14 are housed within one half of the flywheel compartment located alongside the ram means 12.

In the other half of the flywheel chamber there is a movable electric motor 44M, its shaft 70M and a movable flywheel 16.
is accommodated. A movable end plate 84 is provided in place of the fixed end plate 66, and this movable end plate 84
supports a bearing 68 for the lower end of the shaft 70M of the movable electric motor 44M. In addition, the movable end plate 84
The rams cooperate with a number of vertically spaced parallel arm rods 36 to pivot in a direction that increases the spacing between them to engage the rams and form driving communication. Movable flywheel and movable electric motor 4
A frame 34 supported by an axis is defined.

The lower end of the pin 88 has an integrally formed leg 9.
It is fixed so that it cannot be rotated to zero. Leg 9
0 is disposed on the underside of a movable end plate 84 that slides back and forth on the bottom of the housing. The illustrated housing includes a socket 9 with a movable cover 58 at its upper end.
4 is provided with an enlarged portion 92 suitable for receiving a pivot pin rotatably mounted thereon. As shown, the arm rod 86 is joined to the web 96,
It defines a unitary structure that is non-rotatably attached to pin 88. Each of these arm rods 86 and movable end plate 84 supports a bearing 68 for shaft 70M of movable electric motor 44M. A gap 98 formed in the horizontal wall body 78 accommodates the shaft 70M of the movable electric motor, so that the frame 34 mounted on the shaft moves between the engaged position and the disengaged position relative to the shaft 70M. It can be allowed to swing in an arc.

As shown in FIGS. 1 and 3, the pivot axis set by pin 88 is the axis 7 of the movable motor.
It is located behind the spin axis of the movable flywheel set by 0M. Thus, even when fully engaged as shown in FIG. 7, the spin axis remains forward of the pivot axis perpendicular to the path of movement of the ram means toward the extended position. As shown, the ram means is longitudinally slidable and loosely fitted in a groove 100 in the fixed link 32 for driving the clutch, approximately 2.5 mm as required for engagement with the fixed flywheel. cm(1
It is designed to be able to move laterally by a distance of 1 inch). However, once engaged, the ram means follows a straight path defined by the shoulder 102 which provides a guideway or track groove remote from the movable flywheel forcing the ram means against the fixed flywheel. It starts to move. For this,
The angle Θ and normal plane shown in FIG. 1 are defined during forward movement of the ram means. The return movement stroke of the ram need not take place along a straight path, but in fact proceeds along a slightly oblique path.

As can be seen with reference to FIGS. 3-11, a pair of rearwardly extending parallel arms 104 are attached to the rear surface of the lug 26 to limit the distance between the normal extended position and the retracted position. It is arranged within the nozzle 28 so that it can perform a reciprocating motion. These pairs of arms serve a dual function;
Its first function is to guide the ram means according to the groove 100 between an extended position and a retracted position. A second feature is that these pairs of arms are operatively connected to the arms of the pivoted frame 34, thus cooperating with the projections to define a fixed link 32 for driving the clutch. be.

Said pair of arms 104, which provide a guideway for the ram means, are themselves located within grooves 106 symmetrically provided in the bottom wall of the upper rim 48 of the nozzle 28 and handle and in the underside of the movable cover 58. , may be guided for limited reciprocating sliding movement.
In contrast to the ram means 12, the arm 104
06 and its motion is confined to be substantially linear.

As shown in detail in FIGS. 10 and 11,
A fixed limit stop 108 on the underside of movable cover 58 engages a movable limit stop 110 supported by arm 104 to limit forward movement of clutch drive fixed link 32. It can be accomplished. The backward movement of the fixed link 32 is
It is stopped when the protruding piece 26 engages the front end of the nozzle. One or more springs 36 placed between the opposing faces of the nozzle and the lug typically act to bias the lug toward the extended position. The compression spring 36 is a clutch which is automatically actuatable to disengage the clutch as soon as the fixed link 32 for driving the clutch is disengaged by the return movement of the lug toward the normal extended position. It constitutes a means of liberation.

As shown in FIGS. 3 to 7, a large number of ears 112 arranged in a vertical direction are provided at the end remote from the pin 88 of the arm rod 86 of the frame 34 mounted on the shaft. A large number of ears 112 are connected to the arm 1.
Notch 11 of boss 116 formed on one side of 04
It is accepted by 4. Thus, the protruding piece 26
A connection formed between the clutch drive fixed link 32 and the arm 104 operatively connects the arm 104 to the clutch means consisting of a flywheel and an axle frame 34. It can be effective. the projecting piece with a force greater than the biasing force applied thereto by the spring 36;
When the fixed link 32 for driving the clutch is biased by pressing against the work piece, the frame 34 is swung backwards in an arc shape, narrowing the distance between the pair of flywheels, thus reducing the distance between the pair of flywheels. Engagement of the clutch is accomplished by gripping the ram between the flywheels. As previously stated, once engaged, the clutch remains in the engaged position until the ram means is removed from the flywheel. When the ram means leaves the flywheel as shown in FIG. 7, the clutch can be disengaged and, under the action of the compression spring 36 acting as a clutch release element, the fixed link 32 for driving the clutch is automatically disengaged. can be influenced.

In other words, as long as the projecting piece remains pressed against the work piece, the spring 30, which acts to retract the ram means, will pull the ram means rearward into contact with the pair of flywheels. Although taut, the pair of flywheels remains in an inseparable position to prevent passage of the ram means between them. As soon as the pressure on the lug is relieved to the point where it can be extended by the biasing force of the clutch release spring 36, the spacing between the pair of flywheels widens again and the ram means returns. Begins to finish the motor stroke.

The flywheel that engages the surface of the ram means is provided with friction pads 118 made of some wear-resistant material having a fairly high coefficient of friction, such as common brake lining material. When the spring 30, acting to urge retraction of the ram means, biases the ram means rearwardly, the limit stop 12
0 (see Figure 5) comes to work.

As best seen in FIGS. 5, 8 and 9, the forward end of the ram means is shaped to form a projection 122 defined at the top and bottom by a shoulder 124. There is. This protrusion 122 is
When the shoulder 124 engages the cushion 24, it passes through an aperture 126 in the protrusion 26. If there is energy remaining in the ram means at the end of the working stroke, either the cushion absorbs this residual energy or the protrusion of the ram means abuts against the work piece itself.

Figures 5, 6, 7, 11 and 1
FIG. 2 shows the structure of the trigger 54 and the fixed link 32 for driving the clutch.
The manner of secure interconnection between the two is shown in detail.

Trigger 54 is pivotally mounted within the handle opening in a conventional manner and is normally biased forwardly by spring 128. When the trigger 54 is manually moved to the retracted position, the lower rim 1 of the handle
32 serves to close a normally open on-off switch 130 located within.

A vertically located T-shaped hole 134 is integrally formed in the inner web 136 of the handle above the trigger 54. A limiting stop 138 is arranged in the T-shaped hole 134, which has the effect of limiting vertical sliding.
is operatively connected to trigger 54 by link 140. Trigger 54, when driven retracted toward the energized position, serves, via link 140, to lift limit stop 138 and displace its forward projection 142 from arm 104, thereby causing the clutch to disengage. The fixed link 32 as a drive means moves rearwardly to achieve engagement of the clutch. When the trigger is released, the forward projection 142 of the limit stop 138
It serves to prevent the retraction movement of the lug 26 required for engagement of the clutch. Thus, if a working tool were to be dropped, the operator could activate the ram means by actuating the trigger to intermediate the protrusion 142 to prevent engagement of the clutch and thus release the nail. can be operated.

As shown in FIGS. 6, 7, 8 and 9, the fastener receiving frame 64 is of more or less conventional construction with upper and lower parallelogram plates 144 and 146. The pair of plates are interconnected at their leading edges by a wall 148. Additionally, the wall 148 cooperates with the pair of plates to define an opening that opens rearward. A pair of tracks 150 suitable for receiving the body of a fastener 62, such as a nail, therebetween and slidably retaining the fastener in alignment with the protrusion 122 of the ram element; A pair of plates 144
and just inside the opening at the trailing edge of 146. The head of the nail abuts against the track and is advanced into position by being driven by a follower 152 which is tensioned by the action of a coiled tension spring 154.

As shown, a number of nails are connected in a belt by conventional paper tape 156. The nail at the end of the belt chain abuts a stop 158 inside the nozzle across the appropriate opening 60 to hold it in alignment with the protrusion of the ram means. The second nail is held behind the first nail by a track 150. Therefore, when the ram means advances, the first nail is separated from the belt chain and driven into the work piece W by the action of the ram, and subsequently the clutch drive means is disengaged and the clutch is driven. As soon as the ram is opened and the ram means is returned to the retracted position away from the nozzle under the action of the spring, the follower becomes operative to move the second nail into the drive position.
To refill the tensioner receiving frame with the tensioner, the follower can be pulled in much the same way as in a wire sewing machine. Since there is nothing new about the tension device storage frame itself, a detailed explanation of its structure will be omitted. The same can be said of the motor speed control circuit shown in FIG. 12, which includes elements that are mechanically extremely important to the tool itself.

It should also be understood that tools having the parameters listed below are practical and can effectively accomplish the applications described above.

Flywheel diameter: approx. 7.62 cm (3 inches) Flywheel speed: 7000 rpm Ram element speed: approx. 25.4 m/s (1000 in/min)
sec) Electric Motor Horsepower: 1.125 Horsepower Total Tool Weight: Approximately 4.54 Kg (10 lbs) The illustrated embodiment detailed above is specifically intended to be applicable for driving fasteners such as nails. However, it should be understood that the present invention is not limited to such embodiments, and that various modifications can be made. For example, the ram element directly impinges on the workpiece, stamping,
It is also possible to make it work like a punch or a chisel.

Preferred embodiments of the present invention are listed below.

(1) A method for driving a tensioning device, which comprises the steps of rotating a pair of flywheels in opposite directions, and transmitting energy from the flywheels to a ram for driving the tensioning device. Tool drive method.

(2) A driving machine that applies a desired driving force to the object to be driven, comprising: a casing that defines a driving path; and the driving path is directed toward the object;
and ram means adapted to reciprocate in the opposite direction; a flywheel; means for rotating the flywheel; and means for supporting at least one of the ram means and the flywheel; and means for supporting the other unsupported member for movement from a normally spaced position to an engaged position; and moving said flywheel and ram means into driving engagement, control means for moving the ram means along the travel path and in the direction of the driving object so as to apply a desired driving force to the driving object; A driving machine.

(3) A driving machine that applies a desired driving force to the object to be driven, comprising: a casing that defines a driving path; , and a ram means adapted to reciprocate in the opposite direction, a flywheel, and means for rotating the flywheel, the flywheel being proximate but spaced apart from the ram means. means for supporting the flywheel in a normal position, the bearing means being movably mounted, and moving the bearing means to bring the flywheel into driving engagement with the ram means; , moving the ram means along the travel path to apply a desired driving force to the driving object;
and means for moving the driving object in the direction of the driving object.

(4) A fastener-driven driving machine, which includes: a casing that defines a travel route; a flywheel means; a power means for rotating the flywheel means; and a ram means movable within the travel route. , a supply means including a magazine for supplying tensioning tools for sequentially supplying the tensioning tools onto the travel route; and drivingly connecting the flywheel means and the ram means so that the ram means is connected to the travel route within the travel route. a clutch means for driving the tensioning device by propelling the tensioning device along the travel path with a travel stroke toward the tensioning device disposed at the driving path; and a control device for controlling the clutching device. A driving machine characterized by:

(5) A fastener-driven driving machine comprising: a housing defining a travel path; a ram means movable along the travel path with a travel stroke; and a ram supported by the housing. a pair of flywheels rotating in opposite directions, the flywheels rotating in opposite directions; and means for transferring energy from the flywheels to the ram means, thereby propelling the ram means through a travel stroke. A driving machine.

(6) A driving machine for applying driving to a workpiece, the driving machine being adapted to move along a path, and
a ram means having a friction surface with friction of a given coefficient of friction; a rotating body for storing energy to be imparted to the ram means; and the rotating body being brought into engagement with the friction surface of the ram means. Clutching means, the clutching means including means for rotating the rotating body towards the ram means about a pivot spaced apart from the ram means on the other side of the rotating body. A driving machine characterized by:

(7) A hand-held tool that includes a housing, a workpiece working means supported by the housing, and a power unit connected to the workpiece working means located in the housing to operate the workpiece working means. and the power unit includes at least one rotating mass and rotates in one direction with a velocity sufficient to create a precession moment due to gyroscopic motion. In addition, there is another rotating body in the housing that rotates in the opposite direction to this rotating direction, and this rotating body has a speed sufficient to cancel out the precession moment caused by the gyroscope movement. A tool characterized by having mass.

(8) A housing having a protruding nozzle with an opening at its tip, the nozzle communicating with a flywheel chamber behind the housing, and a ram means for sliding movement in the longitudinal direction within the housing; a ram means having a range of motion between a most retracted position within said flywheel chamber and a most advanced position protruding into said nozzle; and a pair of substantially identical ram means rotatably mounted adjacent to said ram means. a flywheel, the axis of rotation of which is a parallel axis perpendicular to the direction of travel; a drive means connected to the flywheel for rotating the flywheels at substantially the same speed in mutually opposite directions; pivot bearing means for at least one axis of the flywheels for relatively arcuate movement in a direction that changes the spacing between the two flywheels; in cooperation with the ram means therebetween to restrict the clutch by frictionally gripping the ram means and propelling it to the point where no further driving contact is possible; Clutch actuating means connected to said pivot bearing means for shifting said flywheel into a ram drive relationship and cooperating with said pivot bearing means when the flywheel is separated from and no longer affected by the clutch actuating means; there are clutch release means for immediately widening the distance between the two flywheels again, and ram return means connected to said ram means;
Driving characterized in that there is a ram return means adapted to automatically return the ram means to its retracted position and to be followed by a subsequent forward movement of the ram means and a movement of the clutch release means. Machine.

(9) One flywheel 16 is movable in an arc around the pivot axis of the attachment means, the spin axis of the other flywheel 14 is fixed in position, and the flywheel movable in an arc swings backwards towards the engaged position. (8) above, characterized in that it is capable of
The driving machine described in section.

(10) The driving machine according to item (8), further comprising a stopper placed on the path of the ram means 12 to prevent the ram means from moving forward. .

(11) The driving machine according to item (8), further comprising a stopper placed on the path of the ram means 12 to stop the ram means in the retracted position.

(12) A clutch drive means is attached to the front end of the nozzle 28 and includes a protruding piece 2 movable relative to the nozzle between an extended position and a retracted position.
6, and a linking element interconnecting the projecting piece and the attachment means and operable to engage the clutch when the projecting piece is moved to a retracted position. The driving machine according to item (8) above.

(13) The clutch release means normally includes a biasing member arranged to bias the attachment means in the direction of disengaging the clutch. Driving machine described in section.

(14) one of the flywheels is arranged to be rotatable about a fixed spin axis, limited to the extent that the ram means 12 moves into a position suitable for frictional engagement with the fixed flywheel; 8. The driving machine according to item (8), wherein the driving machine is arranged so as to be able to perform a horizontal movement.

(15) A retractable stop is normally disposed in operative association with the clutch to maintain the clutch in a disengaged position, and a manual trigger 54 is provided.
is connected to the stopper and is operable, when actuated, to move the stopper to the retracted position and to release the clutch and move it to the engaged position. The driving machine described in .

(16) A second opening is provided in the nozzle 28 along the path of guided movement of the ram means 12 defining a breech of suitable size to receive the implant; The driving machine according to the above item (8), characterized in that means is provided in the vicinity of the driving tool which can act to receive and releasably hold the driving object within the path of travel of the ram means.

(17) the drive means includes at least one electric motor;
A driving machine according to item (8) above, characterized in that a speed control means 18 is electrically connected to the electric motor and is operable to change the rotational speed of the flywheel when driven.

(18) The length of the ram means is related to the position of the clutch so that the ram means 12 can work forward toward a position in which it is not engaged with the clutch before reaching the end of the nozzle 28. The driving machine according to item (8) above, characterized in that:

(19) The driving means includes a pair of electric motors connected to individually drive the pair of flywheels in mutually opposite directions at substantially the same speed. ) The driving machine described in item ).

(20) one flywheel is mounted so that it can rotate in an arc relative to the ram means 12;
The other flywheel is mounted for rotation about a fixed spin axis, and the opposing surfaces of the pair of flywheels 14, 16 and the ram means 12 align with each other with their spin axes parallel. The spin axis of the arcuately movable flywheel configured to contact along a tangential line cooperates with the pivot axis of the mounting means to form a plane intersecting a second plane perpendicular to the direction of motion of the ram means. and the intersection is made at an acute angle such that the tangent value is equal to or less than the coefficient of friction between the contact surfaces of the ram means and the arcuately movable flywheel. The driving machine described in item 8).

(21) Ram means 12 and a pair of flywheels 14, 16
are in contact along a line parallel to the rotational axes of such pair of flywheels, and
The pivot axis of the mounting means and the mounting means are arranged such that, upon engagement of the arcuately movable flywheel and the ram means, the spin axis of the flywheel remains in a position forward of a plane defined by the flywheel itself and the ram means. Driving machine according to item (9), characterized in that the spin axes of the rotatably mounted flywheels are associated with each other and with the line of contact between the flywheels and the ram means.

(22) The mounting means, the arcuately movable flywheel supported on the mounting means, and the ram means are arranged in a plane parallel to the direction of movement of the ram means toward the extended position when the flywheel and the ram means are engaged. are positioned in relation to each other such that they intersect at an acute angle to the plane defined by the spin axis of the flywheel and the pivot axis of the mounting means, and the friction between the contact surfaces of the ram element and the flywheel movable in an arc The driving machine according to item (9), wherein the coefficient is small but equal to the tangent value of the acute angle.

(23) A stopper for forward movement of the ram means consists of a member with a cushion arranged at the tip of the nozzle, and the member with the cushion stops the ram means before it contacts the work piece placed at the front part of the nozzle. The driving machine according to item (10), characterized in that the driving machine is capable of absorbing and dissipating most of the stored excess energy.

(24) A stopper for rearward movement of the ram means,
A driving machine according to item (11), characterized in that it is arranged to stop the ram means in the retracted position so that the clutch begins to engage the ram means at its front end portion.

(25) The length of the ram means relative to the position of the clutch is such that the ram means disengages from the clutch when the front end of the ram means reaches the front end of the nozzle. The driving machine according to item (21) above, characterized by:

(26) No. (22) above, characterized in that the tangent value of the acute angle is smaller than the friction coefficient.
The driving machine described in section.

(27) Paragraph (22) above, characterized in that the ram means and the pair of flywheels are shaped such that their opposing surfaces are in contact along straight tangents parallel to the spin axis. The driving machine described in .

(28) Item (22) above, characterized in that the coefficient of friction is larger than the tangent value of an acute angle.
The driving machine described in section.

(29) According to paragraph (22) above, the spatial relationship between the elements is determined such that the ram means disengages from the clutch before reaching the front end of the nozzle. driving machine.

(30) The direction of movement of the flywheel movable towards the ram means is such that the direction of movement of the flywheel is such that it has a first component perpendicular to the direction of movement during the working stroke of the ram means and a second component in the opposite direction.
The above-mentioned item is characterized in that it contains the following ingredients.
The driving machine described in (3).

(31) The support means includes a lever extending between the axis of rotation of the flywheel and a pivot line perpendicular to the travel path and spaced apart from a plane passing through the axis of rotation. The driving machine described in section.

(32) A driving machine, characterized in that a second flywheel, which is different from the flywheel described in item (31) and rotates in the opposite direction, is attached to the opposite side of the ram.

(33) The driving machine according to item (32), wherein the second flywheel has a rotation axis that is fixed in position relative to the travel path.

(34) The driving machine according to item (4), further comprising adjustable speed control means 18 connected to the power means and serving to control the rotational speed of the flywheel.

(35) The driving machine according to item (4), wherein the control means includes an element responsive to the positioning of the housing in the vicinity of the work piece.

(36) The driving machine according to item (4) above, wherein the control means includes a manually operable element.

(37) The drive according to paragraph (4) above, wherein the power means includes a freely rotatable electric motor, and the control means includes a manually operable electric switch for energizing the electric motor. Insertion machine.

(38) The driving machine according to item (4), wherein the flywheel means is comprised of a pair of flywheels located along both sides of the ram means and rotating in opposite directions.

(39) moving at least one flywheel from a first position in which the distance between the pair of flywheels is greater than the thickness of the ram means to a second position in which the distance is less than the thickness of the ram means; The driving machine according to item (38), characterized in that it includes a connecting means having an element for moving toward the target.

(40) The driving machine according to item (39), wherein the ram means has a portion having a thickness shorter than the interval at the second position.

(41) A pair of flywheels are located on opposite sides of the ram, and the energy transfer means includes a gripping element for sandwiching the ram means between the pair of flywheels. The driving machine described.

(42) Workpiece engagement means supported by the housing and movable in response to engagement with the workpiece; and coupled between the protruding piece and the gripping element, the means being responsive to movement of the protruding piece. The driving machine according to item (41), further comprising link means for controlling the gripping element.

(43) The method for driving a tensioning device according to item (1) above, wherein the energy transfer is achieved by sandwiching a ram means between a pair of flywheels.

(44) Rotating a pair of flywheels in opposite directions, with one flywheel rotating around a relatively fixed axis of rotation and the other flywheel rotating around a relatively movable axis of rotation. The method for driving a tensioning device according to item (43), characterized in that the method is achieved by rotating the tensioning device.

(45) Sandwiching the ram means between the pair of flywheels is achieved by pivoting a relatively movable axis of rotation about an axis spaced apart from a plane containing the axis of rotation. The method for driving a tensioning device according to the item (44).

(46) The fastening device according to item (1), further comprising the step of controlling the amount of energy transferred to the ram means by adjusting the rotational speed of the pair of flywheels. Driving method.

(47) characterized in that the predetermined coefficient of friction and the value of the tangent of an acute angle defined by a line substantially perpendicular to the passage and a line passing through the axis of rotation and pivot point of the rotating body are substantially equal; The driving machine according to item (6) above.

(48) The tool according to item (7), wherein the power unit and the rotating body include a pair of rotating bodies that rotate in opposite directions.

(49) The above-mentioned item (48), wherein the power unit further includes a pair of rotary motors respectively attached to each of the pair of flywheels.
Tools listed in section.

(50) The tool according to item (7) above, characterized in that the pair of rotating bodies is coupled to a workpiece working means.

[Brief explanation of drawings]

Fig. 1 schematically shows the main operating parts of the tool according to the present invention, Fig. 2 is a perspective view of the tool shown in Fig. 1, seen from the upper left side of the rear end, and Fig. 3 clearly shows the internal structure. 4 is an enlarged cross-sectional view taken along line 4-4 in FIG. 3, and FIG. A vertical cross-sectional view taken along the line with the same magnification as in Fig. 4, and Fig. 6 is a longitudinal cross-sectional view taken along the line 6-6 in Fig. 5, with a part cut away to reveal the inside. 7 is a cut-away view similar to FIG. 6 showing the ram means in the fully extended position; FIG. 8 is a view taken along line 8--8 of FIG. FIG. 9 is a partial perspective view with the same magnification as FIG. 8, with a part cut away to clarify the internal structure, and FIG. 5 is a partial cross-sectional view at the same magnification as in FIG. 5, showing details of the energized trigger and the lug remaining in the extended position; FIG. 11 shows the lug in the retracted position; FIG. 12 is a cross-sectional view similar to FIG. 10 and schematically shows the speed control circuit of the electric motor. In addition, W is a work piece, 10 is an embodiment as a nailer,
12 is a ram element (ram means), 14 and 16 are flywheels, 18 is a speed control means, 20 is a control knob, 2
2 is a scale, 24 is a cushion, 26 is a protruding piece, 2
8 is a nozzle, 30 is a tension spring, 32 is a fixed link, 34 is a movable member (frame mounted on an axis), 36 is a compression spring, 40 is a case (casing), 42 is a flywheel compartment, 44 is an electric motor, and 44F is a fixed Electric motor, 44M
is a movable electric motor, 46 is a fixed member, 48 is an upper rim, 50 is a handle, 52 is a wall, 54 is a trigger, 56 is a line cord section, 58 is a movable cover (lid), 60 is an opening, 62 is a Tensioning tools such as nails, 6
4 is a tension tool storage frame (magazine), 66 is a fixed end plate,
68 is a bearing, 70 is a shaft, 70F, 70M is a shaft, 7
2 is a wall, 74 and 76 are motor compartments, 78 is a horizontal wall body, 80 is a flywheel compartment, 82 is a scaffold, 84 is a movable end plate, 86 is an arm rod, 88 is a pin, and 90 is an integrally formed leg. 92 is the large part, 94 is the socket, 96 is the web, 98 is the gap, 100 is the groove, 1
02 is a shoulder, 104 is an arm, 106 is a groove, 10
8 is a fixed limit stopper, 110 is a movable limit stopper, 112 is an ear portion, 114 is a notch, 116
118 is a boss, 118 is a friction piece, 120 is a limiting stopper, 122 is a projection, 124 is a shoulder, 128 is a spring, 130 is an on-off switch, 132 is a rim, 134 is a T-shaped hole, 136 is a web, 138
140 is a link, 142 is a projection, 144 and 146 are plates, 148 is a wall, 150 is a track, 152 is a follower, 154 is a tension spring, 156 is a paper tape, and 158 is a stopper.

Claims (1)

[Claims] 1. A step of sequentially feeding the tensioning tools into the passage of the tensioning tool drive ram, and then a step of rotating the pair of flywheels in opposite directions to generate forces based on opposing rotations. and then moving the tensioner drive ram from at least one of the flywheels by rotating and moving the flywheel so that the flywheel moves in a direction in which it contacts the tensioner drive ram. transferring energy to cause the ram to move such that it drives the tensioner; then disengaging the ram from the flywheel; and then disengaging the ram from the flywheel. A method for driving a fastening tool in electric driving, etc., comprising the steps of: returning the flywheel to its original return position while separating from the ram.