Patent Publication Number: US-7896212-B2

Title: Portable type fastener driving tool

Description:
RELATED APPLICATIONS 
     The present application is a National Phase entry of International Application Number PCT/IB2005/000811, filed Mar. 30, 2005, which claims priority from, Japanese Application Number 2004-105993, filed Mar. 31, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a portable type fastener driving tool which is used to drive fasteners such as nails and pins into a workpiece by hammering them in the axial direction. 
     TECHNICAL BACKGROUND 
     Portable type fastener driving tools can be classified as nail driving devices, pin driving devices (or tack driving devices) and staple driving devices and the like on the basis of the type of fastener which is being driven. On the other hand, they can be classified as devices using compressed air, the pressure of combustion, the brisance of gunpowder and electricity and the like on the basis of the driving source. 
     In any case, fastener driving tools are provided with rods which are used for driving and continuous driving is permitted by supplying the fasteners one by one to the front of the rod. 
     Fasteners which are used with fastener driving tools are made to connecting bodies which are connected by connecting material. The fastener connecting bodies are housed in a magazine and the fasteners are supplied one by one to the front of the rod by feeding them in one pitch increments inside the magazine. 
     There are two main types of connecting modes for a fastener group. In one mode, multiple fasteners are connected so that they are parallel to one another by using a connecting material which is made of a material which can alter its shape such as resinous tape and narrow wire (such as metal wiring) so that this fastener connecting body can be wound to a coiled shape (or rolled or formed like a spiral). This connecting mode is often used for nails. 
     In another connecting mode used for a fastener group, a fastener is retained by a connecting material which extends in a straight line and which is basically rigid. As a result, in this mode, the fastener connecting body cannot be wound in a coil shape. Resin and paper are often used for this type of connecting tool. 
     Further, the only type of fastener connecting body in which (a) the direction in which the fasteners are arranged and (b) the shaft line of each of the fasteners are mutually perpendicular to one another is the one which can be wound in a coil. There are two types of fastener connecting bodies which cannot be wound into coils: the type where (c) the direction in which the fastener group is arranged and (d) the shaft line of each of the fasteners are perpendicular to one another; and the type where (e) the direction in which the fastener group is arranged is tilted toward (f) the shaft line of each of the fasteners. The fact that there are two types in the latter category is brought about by a difference in the position of the magazine. 
     Next, we shall discuss the relation between the structure of the fastener connecting body and the driving tool by providing an example of the nail and the nail driving device. 
     A nail connecting body which has a rectilinear shape is loaded onto a magazine so that it extends in a long straight line. The nail connecting body which has a rectilinear shape is advantageous in that it has an overall rigid body structure and does not require a special motive power and can be fed reliably by using a simple feed mechanism which uses an extension spring or a compression spring. 
     However, since there are limits on the length of the magazine to maintain easy handle and operation for the nail driving device users, there are limits on the length of a single nail connecting body (limits on the number of nails which can be used to make up a single nail connecting body). Therefore, in operations which involve driving a large quantity of nails in a short period of time such as when buildings are built using the 2×4 method, it is disadvantageous in that the nail connecting body must be frequently replaced. 
     On the other hand, nail connecting bodies which can be wound in a coil shape are advantageous in that they are loaded onto a drum shaped magazine which is schematically round when seen in cross section and a large number of nails can be accommodated efficiently inside the magazine. In other words, a single nail connecting body can be consisted of a great many nails. For this reason, it is suitable for operation for construction in which large quantities of nails are used. 
     Be that as it may, the nail connecting bodies which are wound into a coil shape cannot be fed just by pressing (or pulling) on a spring and a feed mechanism which has a movable feed member must be set in place near the rod. 
     For a nail driving tool (a “coil nailer”) which uses a nail connecting body which has been wound into a coil shape, almost without exception an “air tool” which uses compressed air as the drive source is used. Specifically, a small piston used for feeding the nails is driven by compressed air, and the fastener connecting bodies are fed by using a lever which does elliptic movement links with the reciprocating motion of the piston. 
     However, air tools present problems in that they require an air compressor so that maneuverability is lacking on the work site. In addition, since an air hose bring resisting effect to the movement of the tool, there are problems in that a heavy burden in placed on the operator. It is unpleasant for an operator to carry out fastening operations while manipulating a hose at a work site which is cluttered with many members. 
     On the other hand, a “gas tool” which uses gas combustion pressure as the power source for the rod is advantageous in that it does not require special accessory devices and has outstanding maneuverability. As a result, fastening operations can be carried out anywhere and there is little physical burden placed on the operator as there is no hose. However, the prior art gas tool was inconvenient in that it could only be used with a rectilinear nail connecting body so that the nail connecting bodies had to be replaced frequently within a short period of time at a work site where many nail driving operations were being carried out. 
     Therefore, experiments have been carried out to use coil type nail connecting bodies on gas tools (in other words, experiments on developing a gas combustion type coil nailer). An example of this is disclosed in Patent Document 1 in which feeding of nails had been carried out using partial gas combustion pressure as a power source. Specifically, it discloses that on a gas tool (a) a nail feeding device which is equipped with a nail feeding piston like a coil type connecting nail air tool and part of the combustion gas is introduced to a cylinder in which a nail feeding piston is inserted. 
     [Patent Document 1] Publication of Unexamined Utility Model Application H5-72380 
     DISCLOSURE OF THE INVENTION 
     Problems which the Present Invention is Intended to Solve 
     The nail driving device in the aforementioned Patent Document 1 has not yet been brought to market as an actual product despite the latent demand for it. 
     The reasons for this are as follows: (a) combustion gas is generated instantaneously so that it is difficult to supply combustion gas in a stable fashion to a cylinder in which a nail feeding piston is inserted; (b) the nail feeding process should be carried out when the rod moves backward whereas combustion gas is generated when the rod is driven out (when it moves forward) and the timing for the generation of the combustion gas and the timing for the nail feeding do not coincide; (c) when combustion gas is used for nail feeding, the rod driving out power may decline and one is unsure as to whether the nail has been driven in assured way. 
     It is the main object of the invention in this application to take the current state of the art into consideration and to make it possible to use with a coil type fastener connecting body for a gas combustion type driving tool and a gunpowder type driving tool. It is another object of the invention in this application to provide a rich diversity of structures which may be used for the fastener driving tool and to provide reliable nail feeding operations. 
     Means Used to Solve the Problems 
     When prior art fastener driving tools were being developed, there was no conception of feeding fastener connecting bodies by a motive power which was different from the rod drive source. Thus, it could be said that people were at a dead end when they considered the technology in Patent Document 1. On the other hand, the inventors have modified the prior art concept and have carried out repeated tests and experiments and have been able to achieve the invention in this application. 
     This means that the invention indicated in Claim  1  is a nail driving tool which is provided with (a) a main body which houses a rod which drives in the fasteners; (b) a rod driving out means which pushes the rod forward in the axial direction; (c) a head part which is disposed on the front end of the main body and which is provided with a fastener guiding part; (d) a fastener retaining means which loads a fastener connecting body which is made by connecting multiple fasteners using a connecting material so that they are arranged parallel to one another; and (e) a power operated fastener feed means which feeds the fastener connecting bodies which is loaded on the aforementioned fastener retaining means, in the direction in which the fasteners are arranged and which feeds the fasteners one by one in front of the rods; the invention being characterized as having a drive source for the aforementioned fastener feed means which is different from the drive source of the rod driving out means. 
     In the invention in Claim  2 , the aforementioned rod driving out means disposes the aforementioned rod on a piston which is moved forward by the pressure of the combustion gas. As a result, the rod driving out means is provided with (a) a gas combustion chamber; (b) an electric spark type ignition plug which ignites in the gas inside the combustion chamber; and (c) a battery which provides an electric power supply to the aforementioned ignition plug. Meanwhile the aforementioned fastener feed means is provided with an electrically driven actuator such as a motor or an electromagnetic solenoid. Power supply to the aforementioned electrically driven actuator is carried out from the battery for the aforementioned rod driving out means or else a separate feed battery is set in place exclusively for the electrically driven actuator. 
     In the invention in Claim  3 , the aforementioned fasteners are nails and a fastener connecting body which is permitted to be wound in either a coil shape or a roll shape. Meanwhile the aforementioned fastener retaining means is a magazine which is provided with a cover which can be opened and closed at will. This magazine is formed like a drum which is schematically round when seen in cross section so that it can house the nail connecting bodies when it is wound either in a coil shape or a roll shape. 
     The invention in Claim  4  is provided with (a) an electric motor which is used to feed the fastener connecting bodies; (b) a first sensor which is used to detect the movement of the rods; (c) a second sensor which is used to detect the fasteners which are fed either directly or indirectly; and (d) a braking means which is used to stop the motor from turning. It is set so that when the first sensor detects that the rod has moved backwards, the motor is driven and it starts feeding the fasteners. When the second sensor detects that the feeding of the fasteners is complete, inertial rotation of the motor is prevented by the aforementioned braking means. 
     EFFECT OF THE INVENTION 
     According to the process of the invention in this application, the fastener feeding is carried out independently of from the driving of the rod so that the fasteners can be fed precisely without adversely affecting the reliability and the accuracy of the fastener driving carried out by the rod. 
     One specific mode of the present invention involves feeding the fasteners using an electrical actuator in the gas combustion type driving tool (gas tool) as described in Claim  2 . This makes it possible for the fastener connecting body to be fed accurately and reliably even if it is the coil type described in Claim  3 . As a result, the gas combustion type driving tool which has outstanding maneuverability has been successfully placed on the market as a coil nailer. 
     The inventors carried out experiments to see how much electric power is required to feed the nail connecting body which is usually used by using a motor. As a result, it was determined that the nail connecting bodies can be fed using a small amount of electric power. 
     On the other hand, the gas combustion type driving tool has as an indispensable member an ignition plug which ignites gas and a motor-rotated fan as an optional member. Power is fed from a battery to the ignition plug and the fan. This means that the gas type driving tool is provided with a battery which supplies electricity at least to the ignition plug (there are also two types of battery: the charging type and the replacement type). 
     The inventors took note of this point and carried out experiments on power supply to the fastener feed motor from the charging type battery used for the ignition plug and the fan. When they used a charging type battery, they carried out driving operations continuously at the same driving frequency as when they used the conventional gas driving tool by charging it once. As a result, when they carried out fastener feeding using a battery which was originally provided with a gas driving tool, they were able to simplify the structure. 
     Needless to say, an exclusive fastener feed battery may also be set in place. When the head and the magazine are made into a unit and made them exchangeable to be used with the existing gas tool, it is most likely preferable to set in place an exclusive battery for the unit out of consideration of the ease of the wiring operations. In addition, when power supply is carried out using a cord (cable) from an outside power source for the gas driving tool such as that disclosed in [Japanese] Unexamined Patent Application H8-290370, the electrical actuator should be driven using this outside power source. 
     The example of development of the invention in this application is not necessarily restricted to a combination of rod driving using a gas driving tool and fastener feeding using an electrical actuator. In another example of development of the invention the fasteners are fed by setting in place an electrical actuator in a gun using powder which drives the rod when the gunpowder explodes. The fasteners in the air tool can be fed by using the electrical actuator. In this case, it is advantageous in that the degree of freedom of the feed mechanism can be upgraded and it can contribute to make diversity greater in fastener driving tools. 
     In addition, when the prior art gas driving tools were used, the fasteners were fed using a spring so that the fastener connecting body had an overall solid structure. However, there were the following problems. When the fastener connecting body had a solid structure, the residue from the connecting material would scatter thus making for a poor work environment. In addition, the residue from the connecting (tool) would be left on the surface being worked on leading to a deterioration in the appearance of the surface. 
     On the other hand, in one development of the invention in this application, a rectilinear type fastener connecting body, not coil type, could be fed using a gear type (sprocket type) feed means as disclosed in the first practical embodiment of the invention. Thus, the fastener connecting bodies could be fed accurately even if the overall structure was not a rigid body. As a result, it was possible to connect the fastener groups using a soft thin film-like connecting material so that the problems arising from the residue of the connecting material could either be eliminated or ameliorated. 
     Be that as it may, when the fastener driving tool is used, the fasteners must be supplied to the front of the rod after the rod has completely gone backwards. Feeding the fasteners before the rod went back or while it was going forward would lead to an accident or a malfunction. 
     On the other hand, when a gas combustion driving tool is used, the pulling movement of the trigger is detected by an electrical switch, the ignition plug is energized when this trigger switch is turned on and combustion (an explosion) occurs. (However, it should be noted that if the safety device is not operated, the ignition plug will not be energized even if the trigger switch is turned on). 
     Therefore, when fasteners are fed using an electrical actuator, using the signals from the trigger switch is one way of detecting the rod when it moves backward. This means that the time from when the trigger switch is turned on and the rod moves forward and the regression is complete can be found out beforehand. As a result, this is thought to be a control method in which the backward movement of the rod is detected and then the electrical actuator is operated to feed the fasteners. 
     However, there are problems when this method is used in that when the rods stops due to some type of trouble while it is going backwards, the fasteners can no longer be fed and the electrical actuator may be damaged (burnout). In addition, in the prior art, the rods could move forward even if the fasteners were not supplied to the front of the rod so that it was impossible to prevent “mis-shot” wherein only the rod went forward. 
     On the other hand, when the configuration indicated in Claim  4  is used, the backward movement of the rods can be reliably detected so that feeding errors can be prevented. At the same time, “mis-shot” wherein only the rod moves forward can be prevented and the motor can be prevented from rotating excessively which makes it particularly suitable. Further, the first sensor and the second sensor may be a contact type sensor and/or a non-contact-type sensor, however, the contact type sensor is preferable since it is able to prevent malfunctions. 
     OPTIMAL MODE OF CARRYING OUT THE PRESENT INVENTION 
     Next, we shall describe a mode in which the invention in this application is applied to the nail driving device based on figures.  FIG. 1  through  FIG. 26  are the first practical embodiment (main embodiment) of the present invention. 
    
    
     
       BRIEF EXPLANATION OF FIGURES 
         FIG. 1   FIG. 1  (A) Right lateral view of gas combustion type nail driving device;  FIG. 1  (B) a partial inclined view of the nail connecting body. 
         FIG. 2  Frontal view of the nail driving device. 
         FIG. 3  Frontal view showing the magazine when it is open. 
         FIG. 4  Vertical lateral view of the nail driving device. 
         FIG. 5  Right lateral view of the head part. 
         FIG. 6  Inclined view of head part when seen from the front and left, at an incline. 
         FIG. 7   FIG. 7(A)  . . . a partial exploded inclined view of the head part;  FIG. 7  (B) a sectional view of (A) seen along B-B. 
         FIG. 8  An exploded inclined view of the head part and the main body. 
         FIG. 9  An exploded inclined view of the head part and the magazine. 
         FIG. 10  An exploded inclined view of the head part. 
         FIG. 11  An exploded inclined view of the head part. 
         FIG. 12  A left lateral view of the head part. 
         FIG. 13  A sectional view of  FIG. 5  and  FIG. 7  (A) seen along XIII-XIII. 
         FIG. 14   FIG. 14  (A) a diagram showing the subguide body when it is slightly open from the position indicated in  FIG. 13 .  FIG. 14  (B) is a sectional view of  FIG. 14  (A) seen along B-B. 
         FIG. 15  A left lateral view of the main guide body when the gear unit is attached. 
         FIG. 16  A left lateral view indicating the relation of the position of the gear unit and the nail connecting body. 
         FIG. 17  A sectional view of  FIG. 12  seen along XVII-XVII. 
         FIG. 18  A sectional view of  FIG. 12  and  FIG. 13  seen along XVIII-XVIII. 
         FIG. 19  A sectional view of  FIG. 5  and  FIG. 21  seen along XIX-XIX. 
         FIG. 20  An exploded inclined view which explains the state in  FIG. 19 . 
         FIG. 21  A right lateral view of the upper part of the head part. 
         FIG. 22  A sectional view of  FIG. 21  seen along XXII-XXII. 
         FIG. 23  A sectional view of  FIG. 12  and  FIG. 13  seen along XXIII-XXIII. 
         FIG. 24  A sectional view of  FIG. 12  and  FIG. 13  seen along XXIV-XXIV. 
         FIG. 25  A block diagram indicating the relationships in the electrical system. 
         FIG. 26  An explanatory control diagram indicating the relationship between the motor, the brake and the sensors. 
         FIG. 27  A partial lateral view of the nail connecting body in the second mode of carrying out the present invention. 
         FIG. 28  A sectional view of  FIG. 27  seen along XXVIII-XXVIII. 
         FIG. 29   FIG. 29  (A) a schematic view showing the nail connecting bodies when they are fed.  FIG. 29  (B) a diagram of  FIG. 29  (A) seen along B-B. 
         FIG. 30  A schematic diagram of the third mode of carrying out the present invention. 
     
    
    
     (1) OVERVIEW 
     First, we shall provide an overview based on  FIG. 1  through  FIG. 4  and explain the basic operating structure.  FIG. 1  (A) is a right lateral view of the gas combustion type nail driving device (coil nailer);  FIG. 1  (B) is a partial inclined view of the nail combined body N which is used in the nail driving device.  FIG. 2  is a frontal view of the nail driving device when it is in drive enabled mode.  FIG. 3  is a frontal view showing the nail driving device when the magazine is open.  FIG. 4  is a vertical lateral view of the nail driving device.  FIG. 5  is a right lateral view of the head part. 
     As can be seen from  FIG. 1  and  FIG. 4 , the nail driving device is provided with (a) a main body (body) which houses a cylinder  2 ; (b) a head part  3  which is disposed on the front surface of the main body  1 ; and (c) a magazine  4  which is attached to the head part  3  so that it can be attached and detached. 
     As indicated in  FIG. 1  (B), the nail connecting body N is shaped so that it connects multiple nails n which are arranged on two resinous connecting bodies (strips) and this nail connecting body N is housed in the magazine  4  by winding in a coil shape (further, in the explanation given from this point forward, when it is not necessary to distinguish between a single body nail and a connecting body, the term “nail n” is sometimes used). 
     As indicated in  FIG. 3 , the magazine  4  is made up of (a) a fixed member  5  which is attached to the head part  3 ; and (b) a movable member (cover)  6  which is connected to the bottom end of this fixed member  5  by a pin  59  so that it can open and close at will. 
     The main body  1  is provided with (a) a main housing  8  which is hollow and which configures the shape of the main body  1 ; and (b) a rear cover  9  which is anchored to the rear surface of the main housing  8  by screws. (c) A grip (handle)  11  which is hollow and which is provided with a trigger  10  on the top end and (d) a front part  12  which is positioned so that it slants forward when seen from the side and positioned at the front of the grip are disposed on the bottom surface part of the main housing  8  so that they extend downward. 
     A fuel cell chamber with an opening which faces downward and which is closed by a cap is located on the front part  12 . A gas cartridge (gas cylinder)  15  is housed in this fuel cell chamber. The gas cartridge  15  can be inserted and removed by opening and closing the cap. There is an open space on the bottom of the grip  11  and a charging-type battery  13  is housed in this open space. 
     Further, the grip  11  is hollow and a circuit unit (not shown in figure) which controls the driving operations is disposed inside this. The front part  12  and the lower end of the grip  11  are connected so that they form an integral piece. A support bracket part  16  which retains the magazine so that it does not fall is disposed on the front of the bottom end of the front part  12  so that it protrudes. 
     As can be seen from  FIG. 4 , the nail connecting bodies N which are housed in the magazine  4  are fed to the head part  3  in one pitch increments and the nail n is moved forward by the impact of the rod  17  and is driven into the workpiece. 
     (2) BASIC STRUCTURE OF OPERATIONS 
     Next, we shall provide a simple explanation of the basic structure of the nail driving device operation based on  FIG. 4 . A piston  19  is inserted inside the cylinder  2  so that it can slide at will. A rod  17  (a driver blade or a hammer blade) is attached to this piston  19 . In this mode of carrying out the present invention, the rod  17  is attached to the piston  19  by a screw-in. The rod  17  can also be made so that it forms an integral structure with the piston  19 . 
     Further, when a structure and indicated direction are specified in the Specification by wording such as “up and down”, “left and right” and “front and backward”, “left and right” is based on the direction facing the user (the direction in which the rod moves forward and the direction opposite that). “Front and backward” is based on the direction in which the rod  17  either moves forward or backward. “Up and down” is based on the state wherein the user maintains the nail driving device at a position where the rod  17  is horizontal. As a result, the head part  3  is disposed at the front of the main body  1  and the magazine  4  is disposed at the bottom of the head part  3 . 
     The fan  21  which is driven by the fan motor  20  is disposed at the rear of the cylinder  2 . The fan motor  20  is fixed to the cylinder head  23 . The space between the rear end of the cylinder  2  and the cylinder head  23  is combustion chamber  24 . 
     As a result, the fan  21  is disposed inside the combustion chamber  24 . The fan  21  is main part used for stirring together the combustion gas and the air, for scavenging the combustion gas and for cooling the member which encompasses the combustion chamber  24 . An ignition plug  25  which faces the combustion chamber is disposed on the cylinder head  24 . Further, the cylinder  2  may be made into the combustion chamber  24 . 
     The schematic rear half of the cylinder  2  is hollow and is surrounded by the valve sleeve  26  which can move back and forth in the axial direction of the rod  17 . The valve sleeve  26  forms a part of the safety device so that the rear part has the larger outer diameter. Then, when the nose member  27  (to be discussed in detail later on) makes contact with the workpiece, the valve sleeve  26  moves backward whereupon the rear part of the valve sleeve  26  fits together perfectly with the cylinder head  23 . At the same time, the front part of the valve sleeve  26  of smaller diameter fits together perfectly with the periphery of the cylinder  2 . Accordingly, the combustion chamber  24  is sealed and at the same time that it became the lock-released condition in that if the trigger  10  is pulled the ignition plug  25  could be energized. 
     The combustion gas which fills the gas cartridge  15  is supplied to the combustion chamber via a dosing nozzle (not shown in figure) and a control valve. An intake opening  28  is also located on the rear cover  9  in order to mix the air with the combustion gas. The rear part fan  22  and the rear part of the cylinder head  23  are surrounded by the guide member  29  so that the air can flow suitably into the combustion chamber  24 . An interval is also located between the guide member  29  and the sleeve  26 . An aperture which opens to the front is located between the main housing  8  and the cylinder  2 . 
     When the valve sleeve  26  goes backward and the trigger  10  is pulled, the fan  21  turns and the fuel gas and the air are stirred together in the combustion chamber  24  and at the same time the ignition plug  25  is energized, the mixed gas is ignited and the gas burns (explodes). This makes it possible for the piston  19  and the rod  17  to move forward and the nail to be driven out. A buffer member  30  which is used to absorb the shock of the piston  19  is disposed on the front end part of the cylinder  2 . 
     An auxiliary front surface member  31  which makes up the front surface of the main body  1  is anchored to the front end surface (front end) of the cylinder  2  by screws (not shown in figure). A protruding part  32  which is disposed on the top and on the bottom of the rod  17  is formed on the front surface member  31  and fixes the head part  3  onto this protruding part  32  (the head part  3  may be fixed directly to the front surface of the cylinder  2  or to the front surface of the main housing  8 ). Next, we shall describe the head part  3  and the magazine  4  by referring to  FIG. 6  and following figures. 
     (3). OVERVIEW OF HEAD PART AND MAGAZINE 
       FIG. 6  is an inclined view of the head part  3  seen from the front and inclined to the left.  FIG. 7  (A) is a partial exploded inclined view of the head part  3  when attached to the magazine  4  seen from the front and inclined to the right.  FIG. 7  (B) is a sectional view along B-B in  FIG. 7  (A).  FIG. 8  is an exploded inclined view of the head part  3  and the main body part  1 .  FIG. 9  is an exploded inclined view of the head part  3  and the magazine  4 .  FIG. 10  and  FIG. 11  are exploded inclined views of the main members which make up the head part  3 .  FIG. 12  is a left lateral view of the head part  3 . 
       FIG. 10  will help to provide an overall understanding of these parts. The head part  3  is provided with (a) a main guide body  36  which has a guide tube  35  which guides the forward motion of the nail n and the rod  17 ; (b) a subguide body  37  (which could also be called a cover member) which is shaped like a schematic plate which overlaps the right lateral side of the main guide body  36 ; (c) a gear cover  38  which overlaps with the left lateral surface part of the main guide body  36 ; and (d) a motor case  40  which is anchored to the gear cover  38  by the screw  39 . 
     The main body part of the main guide body  36  is formed like a block plate. A guide tube  35  in the front and back in the lengthwise direction is disposed on the top end of this so that they form an integral piece. The front end part of the guide tube  35  becomes a front facing protruding part  35   a  which protrudes somewhat from the main body part of the main guide body  36 . And the attachment part  41  in the right and the left widthwise direction is disposed on the rear part of the main guide body  36 , and the attachment part  41  is anchored to the protruding parts  32  and  33  with the screw  42 . 
     The hinge parts  36   a  and  37   a  are disposed on the upper end part of (a) the main guide body  36  and (b) the subguide body  37  so that they protrude. These hinge parts  36   a  and  37   a  are connected by a hinge pin  43  from front to back in the lengthwise direction. As a result, the subguide body  37  is lifted and turned centering on the shaft  43 , as indicated in  FIG. 3 . 
     When the subguide body  37  is closed, the upper part of the magazine  4  is clamped and retained on the bottom end between the main guide body  36  and the subguide body  37 . At the same time, a part under the bottom of the guide tube  35 , and between the main guide body  36  and the subguide body  37  is formed as a nail guide space  44  in order to feed the nails n to the guide tube  35 . In addition, the guide tube  35  opens downward toward the nail guide space  44 . As a result, only the front part and the back part of the guide tube  35  are tube shaped. 
     Meanwhile, a sectional schematically semicircular gear chamber  45  is formed as a recession on the top of the left lateral surface of the main guide body  36  so that it extends to the front and to the rear. The gear unit  46  is retained by the gear chamber  45  and the gear cover  38  so that it can turn at will and cannot fall out of place. Then, the gear unit  46  turns and is driven intermittently by the feeding motor  47  which is housed in the motor case  40  so that the nail connecting body N is fed in one pitch increments. 
     A direct current pulse motor (step motor) may be used for the feed motor  47 . Brakes can be applied in the feed motor  47  by applying a current so that it turns inversely. A mechanical brake such as an electromagnetic brake may be used as the braking means. 
     The head part  3  is provided with a nose member  27  which makes up part of the safety device, as indicated in  FIG. 7  (A) and in  FIG. 8 . The nose member  27  is formed on the top of the main guide body  36  so that it extends to the front and to the back. The front end part (front part) is formed as a tube part  27   a  which is inserted loosely on the front facing protruding part  35   a  on the guide tube  35 . In addition, the rear part of the nose member  27  is fastened to the intermediate interlocking member  49  which is a metal plate by a bolt  50 . 
     The intermediate interlocking member  49  is formed so that it has a two branch forked shape when seen on a plane. The rear facing foot part  49   a  passes through the front surface member  31  of the main body  1  and extends inside the main housing  8  and is fixed to the valve sleeve  26  using a screw and the like. The intermediate interlocking member  51  is pushed in the forward direction by a spring which is not shown in the figure. 
     When the nose member  27  goes forward, the safety device locks and the trigger  10  cannot be pulled. As a result, this prevents “shooting in the air” wherein the nail n is mistakenly discharged into the air. 
     Then, when the nose member  27  makes contact with the workpiece W, the nose member  27  moves backward relative to the head part  3  and the main body  1  so that the valve sleeve  26  goes backward and the combustion chamber  24  (see  FIG. 4 ) is sealed. At the same time, the ignition plug  25  can be energized by pulling the trigger  10 . In other words, the lock on the safety device is released and as the result that the nail can be driven toward the workpiece W. 
     Further, when the actual product is used, a front cover  51  which covers the nose member  27  should be disposed so that the user can not operate the nose member  27  manually, as indicated by the dot-and-chain line in  FIG. 1 . The front cover  51  should be formed so that the opening and the closing of the subguide body  37  is not impeded and it should be fixed to the front surface of the main body  1  by screws. 
     As indicated in  FIG. 8 , the bolt insertion hole  52  on the intermediate interlocking member  49  is made long so that it extends for a long way in the front direction and the back direction. As a result, the front and rear positions of the nose member  27  can be adjusted. The driving depth of the nail n can be adjusted by adjusting the front and rear positions of the nose member  27 . 
     Needless to say, the structure of each of the members which make up the head part  3  may be altered if necessary. For example, the guide tube  35  may be configured separately from the main guide body  36  and both of these may also be fastened with a screw and the like. 
     (4) OPENING AND CLOSING STRUCTURE OF THE SUBGUIDE BODY AND CLOSING STRUCTURE OF THE MAGAZINE 
     Next, we shall describe the opening and closing structure of the subguide body and the closing structure of the magazine referring to  FIG. 13  and  FIG. 14 .  FIG. 13  is a sectional view of  FIG. 5  and of  FIG. 7  (A) along XIII-XIII.  FIG. 14  (A) is a diagram indicating the subguide body  37  when it is somewhat opened from the state indicated in  FIG. 13 .  FIG. 14  (B) is a sectional view of  FIG. 14  (A) along B-B. 
     For example, a fixed pawl  54  which protrudes towards the side of the subguide body  37  is disposed on the rear and lower part of the main guide body  36 , as indicated in  FIG. 9 . Meanwhile, a first bracket part  55  which encloses the fixed pawl  54  from the top and the bottom is formed on the rear and lower part of the subguide body  37 . A movable pawl  56  which latches to and unlatches from the aforementioned fixed pawl  54  is attached to the first bracket  55  using a pin  57  which goes in the upper and lower directions lengthwise. A collar is inserted in the pin  57 . 
     A hooking part on the fixed pawl  54  protrudes to the front. A hooking part on the movable pawl  56  protrudes to the rear. An operating piece  56   a  is disposed on the movable pawl  56 .  FIG. 13  indicates both pawls  54  and  56  when they are engaged. The movable pawl  56  is pushed to a position where it engages with the fixed pawl  54  by using a twisting spring which is wound around the collar. When the movable pawl  56  is unlatched from the fixed pawl  54 , the subguide body  37  can be pushed up and turned so that the nail connecting body N can be replaced and the inside of the heat part  3  can be inspected. 
       FIG. 9  is an overall view of the magazine  4 . It is made up of a half drum-shaped fixed member  5  and a movable member  6 . Both of these are connected by the hinge parts  5   a  and  6   a  which are disposed on the lower ends of them, with a pin  59  (other connecting structures may be used as well). In addition, on the fixed member  5  and the movable member  6 , protruding parts  5   b  and  6   b  are formed so that they protrude opposite from the hinge parts  5   a  and  6   a . The surface where both protruding parts  5   b  and  6   b  face each other is flat surface  60  which is used to guide the nail n. 
     The fixed member  5  and the movable member  6  of the magazine  4  overlap exactly at the location where the edge parts  5   c  and  6   c  extend in the radius direction. When the edge parts  5   c  and  6   c  overlap, a nail space  44  which makes it possible for the nail n to be moved is formed between the flat surfaces  60 . As a result, there is a difference in levels between the flat surface  60  and the edge parts  5   c ,  6   c . A pair made up of a protruding strip  61  and a grooved strip  62  is formed so that they fit together on the edge parts  5   c  and  6   c  of the fixed member  5  and the movable member  6 . 
     A first guide groove  63  through which the head a 1  of the nail n passes and a second guide groove  64  through which the connecting material S passes are formed on the opposing surfaces of the flat parts in the fixed member  5  and the movable member  6 . The nail connecting body N in the mode for carrying out the present invention is connected by two connecting material S and both connecting material S are made so that they fit into the second guide groove  64 . 
     As can be seen from  FIG. 9  through  FIG. 11 , the end surfaces of the protruding part in the fixed member  5  and the movable member  6  are made so that they make contact with the lower surfaces of the main guide body  36  and the subguide body  37 . In addition, insertion parts  66  and  67  which fit between the main guide body  36  and the subguide body  37  are formed on the protruding parts where the fixed member  5  and the movable member  6 . 
     The insertion part  66  of the fixed member  5  is formed so that it has a schematic angular shape when seen from the side. Therefore, a groove  68  with an opening which faces downward and also has an angular shape when seen from the side is formed on the main guide body  36 . This makes it possible for the magazine  4  to be retained so that it can neither move forward nor to the rear. 
     In addition, as shown in  FIG. 7(B)  a step part  66   a  which opens toward the movable member  6  is formed on the upper end of the protruding part  66  of the fixed member  5 . Meanwhile, a thin part  68   a  which fits into the aforementioned step part  66   a  is formed on the main guide body  36 . This makes it possible to prevent the fixed member  5  from being displaced to the direction of the movable member  6 . 
     The fitting part  66  of the fixed member  5  is interposed between the lower ends of the main guide body  36  and the subguide body  37  so that an interval can be maintained between the main guide body  36  and the subguide body  37  and a nail guide space  44  can be formed. In other words, the fixed member  5  functions as a spacer to forms the nail guide space  44 . 
     In addition, the protruding part  66  of the fixed member  5  is fixed by pressing on the main guide body  36  using the extension part  69   a  of the control circuit protection cover  69  (to be described later on). As a result, the fixed member  5  is retained so that it cannot be displaced in any direction, either to the front or to the back or to the left or to the right. In addition, a latching part  70  which fits into the support bracket part  16  of the main body  1  so that it cannot fall is formed on the rear and lower end part of the fixed member  5 . 
     (5) NAIL FEED MECHANISM 
     Next, we shall provide a detailed description of the nail feed mechanism by referring to  FIG. 15  through  FIG. 21 .  FIG. 15  is a left lateral view of the main guide body  36  when the gear unit  46  is attached.  FIG. 16  is a left lateral view showing the relation of the positions of the gear unit  45  and the nail connecting body N.  FIG. 17  is a sectional view of  FIG. 12  along XVII-XVII.  FIG. 18  is a sectional view of  FIG. 12  and  FIG. 13  along XVIII-XVIII.  FIG. 19  is a sectional view of  FIG. 5  and  FIG. 21  along XIX-XIX.  FIG. 20  is an exploded inclined view used to explain the state indicated in  FIG. 19 .  FIG. 21  is a right lateral view of the upper part of the head part  3 .  FIG. 22  is a sectional view of  FIG. 21  along XXII-XXII. 
     The gear unit  46  is provided with—starting from the front—(a) a slave gear  72 ; (b) three feed gears  73 ; and (c) a rotation detection gear  74 . These are fixed to a single center shaft  75  by screws and the like. Both ends of the center shaft  75  are supported by a bearing  76  so that it can rotate freely. Each of the gears  72 ,  73  and  74  are retained so that they cannot be displaced in the axial direction. The three feed gears  73  are formed so that they form an integral piece with a single shaft (these may also be formed separately from one another). 
     The slave gear  72  is a twisting gear (helical gear) which causes the gear teeth to slope along the shaft line. The drive gear  78  which is attached to the main shaft  77  of the feed motor  47  engages with this slave gear  72 . The drive gear  78  also is a twisting gear which causes the gear teeth to slope along the shaft line. When the shaft lines of the slave gear  72  and the drive gear  78  intersect as indicated in the mode of carrying out the present invention, an interlocking mechanism which is made up of a level gear and a worm gear and an interlocking mechanism which is made up of a pair of bevel gears may be used. 
     The feed gear  73  is exposed in the nail guide space  44  for the nail n. As a result, a first window hole  79  which is used to expose the feed gear  73  in the nail guide space is formed on the main guide body  36  as indicated in  FIG. 18  and  FIG. 11 . 
     The tooth profile of the feed gear  73  is indicated in  FIG. 18  and  FIG. 19 . The nail connecting bodies N are fed in one pitch increments by interlocking with the shaft of the nail n. In this mode of carrying out the present invention, ten gear teeth  73   a  are formed on the feed gear  73 , however, the number of gear teeth  73   a  may be set to any number depending on the relation to the outside diameter. In addition, each of the gear teeth  73   a  are formed so that the front part toward the direction of rotation extends in a schematic straight line when the rear surface toward the direction of rotation is shaped like a circular arc. This makes it easy to draw the nail n out. 
     As can be seen from  FIG. 16 , the two feed gears  73  are disposed so that they engage with the nail n on both sides which clamp the two connecting material S. As a result, this is a state whereby the two connecting material S are drawn out simultaneously by the feed gear  73 . Therefore, it is advantageous in that the nail is retained so that it is parallel to the shaft line of the guide tube  35  and the nail connecting bodies N are fed accurately. 
     (6) MEANS FOR STABILIZING NAIL FEEDING 
     As indicated in  FIGS. 19 and 20 , the nail connecting body N is pressed toward the gear unit  46  by two presser rollers  80 —upper and lower—as an example of the presser means. This makes it possible to prevent the nail connecting body N from drifting so that the nails n can be fed accurately to the guide tube  35 . 
     The presser roller  80  is attached by a shaft running forward and back in the lengthwise direction on a bearing tool  81  which looks like a box with the left side missing when seen on a plane. It fits into the holder part  81  which is formed on the subguide body  37  and it is pressed by the spring  83 . The spring  83  fits into the spring case  84 . The spring case  84  is fixed to the holder part  81  by the screw  85 . 
     Then, a hole on the holder part  82  is made so that it is a square hole so that the presser roller  80  is retained at a position where it is level. In addition, upper and lower bulging parts  82   b  are formed on the back surface part  82   a  of the bearing fitting  82  while step parts  86  (counterbore hole) are formed on the holder part  81  which accept a bulging part  82   b  on the bearing fitting  81  so that it can slide easily. The presser roller  80  is permitted to go backward to a certain extent so that it resists the spring  83 . 
     Thus, the presser roller  80  moves both far away from and close to the gear unit  46  in resistance to the spring  83  so that the nail connecting body N is retained at a position where it does not drift so that the feed process is not impeded. In addition, the group of nails n is able to secure a state whereby it engages securely with the feed gear  73 . Further, the pressure means for the nail connecting body N is not necessarily restricted to a pressure roller and another type of member such as a lever shaped member may also be used. A plate spring presser member may also be used. The presser roller  80  has been omitted in  FIG. 18 . 
     As indicated in  FIG. 21  and  FIG. 22 , a position retaining lever  87  which is used to retain the position of the nail n is attached at a site which approaches the front part of the subguide body  37 . This position retaining lever  87  is exposed to the nail guide space from the second window hole  88  which opens onto the subguide body  37 . 
     This position retaining lever  87  is provided with a support part  87   a  which supports one nail n in the position just before it moves to the guide tube  35 . At the same time, the upper end surface is formed as the guide surface  87   b  which has a curvature radius which is slightly larger than the outer diameter of the head a 1  of the nail n when seen from the front. Then, the lower end of the position retaining lever  87  is connected to the second bracket part  89  which is disposed so that it protrudes outward on the subguide body  37  with a pin  90  which is long both in front and in the rear in a lengthwise direction. 
     Therefore, the position retaining lever  87  turns to the left and right while centering on the lower end part of this. In addition, by using a twisting spring  92 , it inclines toward the main guide body  36  and is pressed in the direction of rotation. As a result, the position retaining lever  87  rotates in resistance to the spring thus permitting the feeding of the nail connecting body N. In addition, the position retaining lever  87  brings a position which is somewhat higher than the center of rotation into contact with the inclined stopper part  91  of the subguide body  37  so that the position which leans toward the main guide body  36  is regulated. 
     Although it is a supplementary explanation, when the position retaining lever  87  is completely inclined towards the main guide body  36 , the guide surface  87   b  of the upper end of this becomes concentric with the guide tube  35  when seen from the front. As a result, the head a 1  of the nail which is driven out is guided as it passes through and is able to be held to go forward directly. In addition, by supporting the succeeding nails n using a support part  87   a , a position which is parallel to the guide tube  35  can be retained in conjunction with each of the feed gears  73  even if the nails n are long. 
     As a means of retaining even a long nail n at a precise position, disposing the multiple feed gears  73  at wide intervals is one way, but when the feed motor  47  is disposed at a position which approaches the front side of the head part  3  like this mode of carrying out the present invention, the feed gear  73  cannot be disposed at a location which approaches the front side of the head part  3 . 
     On the other hand, as indicated in the mode of carrying out the present invention, the group of feed gears  73  is disposed so that it approaches the rear part of the head part  3 , and the position retaining lever  87  is set in place at a location which is on the side of the head part  3  which is close, the degree of freedom of disposing the feed motor  47  can be ensured and the long nails can be retained at an exact position which is advantageous. 
     The motor  47  may be disposed on the upper surface part of the head part  3 , however, it makes difficult to design the nose member  27  and it also makes difficult for the operator to see the surface being worked on during operations. As a result, when placed on one of the left and right side surface parts of the head part  3 , as indicated in this mode of the invention, this is suitable as malfunctions such as interference with the nose member  27  and difficulty in seeing the surface being worked on can be avoided. In addition, a feed device such as the motor  47  and the gear unit  46  should be disposed on a fixed member such as the main guide body  36 . 
     (7) SUPPLEMENTARY EXPLANATION OF NAIL FEEDING 
     For example, as can easily be seen from  FIG. 22 , part of the outside of the radius of the gear unit  46  in the nail guide space  44  is formed on the circular groove  44   a  which has a moderate curvature which is centered on the shaft center (rotation shaft center of the feed gear  73 ) of the gear unit  46 . A rectilinear part  44   b  extends from the upper end of this circular groove  44   a  towards the nail guide tube  35 . The meaning of this configuration is as follows; 
     Needless to say, however, it can be configured so that the nail guide space  44  extends in a rectilinear direction from the magazine  4 . On the other hand, the engagement (latching) of the feed gear  73  with the nail is strongest at a part which is exactly horizontal to the shaft center and the engaging function with the nail n declines as the farther away it goes from the horizontal position to both upwards and downwards. 
     Then, when the nail guide space  44  is a simple shape such that is extends in a rectilinear fashion up and down, the shaft center of the feed gear  73  must be distanced from the nail guide space  44 . Therefore, the catching function to the nail n of the gear tooth  73   a  deteriorates and as a result, it may not be possible to ensure the sufficient engagement of the feed gear  73  and the group of nails. 
     On the other hand, when the nail guide space  44  is formed as it extends in a circular shape at a position right beside the feed gear  73 , the length at which the group of nails and the feed gear  73  engage can be made longer circumferentially so that the meshing depth of the group of nails and the feed gear  73  can be ensured and the group of nails can be fed reliably. 
     In addition, setting a presser roller  80  is suitable since the engagement of the feed gear  73  and group of nails can be made more reliable. 
     (8) CONTROL OF NAIL FEED 
     Next, we shall explain how the feeding of nails n is controlled by referring to  FIG. 23  through  FIG. 26  mainly.  FIG. 23  is a sectional view of  FIG. 12  and  FIG. 13  along XXIII-XXIII.  FIG. 24  is a sectional view of  FIG. 12  and  FIG. 13  along XXIV-XXIV.  FIG. 25  is an explanatory diagram indicating the control relationships in the electrical system.  FIG. 26  is an explanatory view indicating the control relationship of the feed motor  47 , the braking circuit  48  and the sensors. 
     In this mode of carrying out the present invention, the control means for driving out the nails n is provided with (a) a first sensor  93  which is used to detect the movement of the rod  17 ; (b) a second sensor  94  which is used to detect the nails n when they are fed; and (c) a control circuit which controls the feed motor  47  as well as the braking circuit  48  based on the movement of these sensors  93  and  94 . 
     As indicated in  FIG. 15  and  FIG. 18 , the control circuit is provided with a circuit substrate  95 . The circuit substrate  95  is attached to the left side surface of the main guide body  36 . In addition, the circuit substrate  95  is covered by a protective cover  69 . The protective cover  69  is fixed to the main guide body  36  by the screw  96 . The protective cover  69  has an extension part  69   a  which extends as far as the front end part of the main guide body  36 . As indicated previously, the fixed member  5  of the magazine  4  is pressed down and retained by this extension part  69   a.    
     As indicated in  FIG. 23  and  FIG. 24 , the first sensor  93  is disposed on the pocket part  97  which is formed on the rear parts of the main guide body  36  and the gear cover  38  so that these communicate with one another. The first sensor  93  uses a limit switch (microswitch) which is provided with a movable contact  93   a . This movable contact  93   a  is disposed in slightly front of the rod  17  which is located at the position of regression. 
     The main body of the first sensor  93  is fixed to either the main guide body  36  or the gear cover  38 . The terminal  98  is exposed outside the gear cover  38  via a hole. The terminal  98  and the circuit substrate  95  are connected by a cable  100  which is provided with a plug  99 . This terminal has been omitted from  FIG. 24 . 
     As indicated in  FIG. 15  and  FIG. 23 , the second sensor  94  is fixed to the main guide body  36  and is covered by a hollow part  97   a  on the gear cover  38 . This second sensor  94  makes use of a limit switch (microswitch) which is provided with a contact  94   a . The contact  94   a  is brought into contact with the circumferential surface of the rotation detection gear  74 . 
     The profile of each of the teeth of the rotation detection gear  74  is formed like a gently sloping conical shape. This makes it possible to ensure that the movement of the contact  94   a  of the second sensor  94  is smooth. Needless to say, the number of gear teeth in the rotation detection gear  74  coincides with the number of gear teeth of the feed gear  73 . The signal cable  100  of the second sensor  94  is also connected to the circuit substrate  95 . 
     Further, in this mode of carrying out the present invention, the detection of the nail was carried out instead by the rotation detection gear  74 , however, it can also be configured so that the nails nearest to the guide tube  35  are detected directly by the second sensor  94 . 
     As indicated in  FIG. 25 , a drive system  101  which controls the driving out of the nails and a feed system  102  which controls the feed of the nails n are present in the nail driving device as an electrical system. The drive system  101  is provided with a battery  13 , an ignition plug  25 , a fan feed motor  47 , a trigger switch  104  which is turned on when the trigger  10  is pulled and a control circuit (not shown in the figure). 
     On the other hand, the feed system  102  is provided with a feed motor  47 , a braking circuit  48 , a first sensor  93 , a second sensor  94  and a control circuit  105 . Then, electric power is provided from the battery  13  in the drive system as a power source for the feed system  102 . The control circuit is provided with a microcomputer. The braking circuit  48  is one part of the control circuit, however, in  FIG. 25 , it is indicated separately from the control circuit  105  to facilitate the explanation. 
       FIG. 26  indicates in terms of a time series how the feed motor  47  and the braking circuit  48  and both sensors  93  and  94  are related in the feed system  102 . The energizing status of the feed motor  47  and the braking circuit  48  is ON. 
     In the first sensor  93 , the state wherein the contact  93   a  does not make contact with the rod  17  (that is, the state wherein the rod  17  has completely regressed) is detected as ON. In addition, in the second sensor  94 , the state wherein the contact  94   a  moves from trough to trough of the rotation detection gear  74  (in other words, the state whereby the double duty rotation gear  74  turns at 1 pitch) is detected as ON. 
     Further, ON and OFF in both sensors  93  and  94  are unrelated to whether or not there is an energizing state but in order to conserve power consumption, to process the energizing interception state for the first sensor  93  as an ON signal and the energizing state should be processed as an OFF signal. The second sensor  94  is processed so that the energizing state is ON. 
     Then, when the first sensor  93  goes from OFF to ON and the feed motor  47  starts driving, after a short time lag, the second sensor  94  goes ON (the rotation detection gear  74  turns when the feed motor  47  turns, however, there is somewhat of a time lag while the movement of the contact  94   a  changes to signals. As a result, the ON operation of the second sensor  94  is slightly delayed after the start of feed motor  47 . 
     Then, when each of the gears  72 ,  73  and  74  turn at an angle at which the nail connecting body N is sent by one pitch, the second sensor  94  switches from ON to OFF. The feed motor  47  stops being driven by the signal changes from ON to OFF in the second sensor  94  and after a very short time has passed (for example, two hundred or three hundred microseconds), the braking circuit  48  goes ON and the inertial rotation of the feed motor  47  is prevented. 
     OFF signal of the first sensor  93  is the prerequisite for the rotation of the feed motor  47  so that the feed motor  47  does not turns without the rod  17  completely going backwards and burnout of feed motor  47  and other types of malfunctions are prevented. 
     However, when the energizing of the feed motor  47  and the energizing of the braking circuit  48  overlap, this leads to burnout of the feed motor  47  or excess consumption of electric power. In addition, there is a very small time lag between (a) the rotation starting and the rotation ending of a contact and (b) the sending of the signals in the second sensor  94 . The contact  94   a  of the second sensor  94  goes past the peak of the rotation detection gear  74  and before completely entering the trough of the rotation detection gear  74  (in other words, before each of the gears  72 ,  73  and  74  turn at a predetermined angle) the OFF signal appears on the second sensor  94 . 
     Therefore, if each of the gears  72 ,  73  and  74  stop turning at the same time that the OFF signals of the second sensor  94  are sent, it is possible that the actual rotation angle will be slightly smaller than the angle required to feed a one-pitch of nail connecting body N. 
     On the other hand, when a slight time difference is set from the time the feed motor  47  is turned OFF to the time when the braking circuit  48  is turned ON, as indicated in the mode of carrying out the present invention, simultaneous energizing to the feed motor  47  and to the braking circuit  48  is prevented. At the same time, the time lag between the rotation of the contact  94   a  and the signals sent is absorbed and each of the gears  72 ,  73  and  74  can be rotated accurately in accordance with the extent of the standard angle. 
     In addition, when the feed is controlled to the extent that the feed gear  73  is rotated, it is possible that errors will accumulate while the nails are repeatedly driven and it will no longer be possible to feed the nails n accurately. 
     On the other hand, in this mode of carrying out the present invention, the feed motor  47  can be stopped reliably each and every time by turning the second sensor  94  OFF. As a result, the slight time difference in the rotation of the gears  72 ,  73  and  74  can be adjusted (reset) every time so that it is no longer necessary to set an encoder in place to detect the rotation of the feed motor  47  accurately thus this mode is advantageous and practical. 
     A safety circuit which is used to stop the energizing process if a larger load than permitted is placed on the feed motor  47  is disposed on the control circuit to prevent the feed motor  47  from becoming damaged when an excess load is placed on the feed motor  47  for some reason such as the nails becoming jammed. 
     Further, if the rod  17  moves forward even though a nail n has not been supplied to the guide tube  35 , the fuel is wasted. Therefore, for (a) the ignition of the ignition plug  25  by the trigger switch  104  ON (b) the ON state of the safety switch  103  and (c) the ON state of the second sensor  94  may be able to be used as prerequisites. A typical example of this is indicated by the dotted line scheme in  FIG. 25 . 
     When the nail n is fed using the feed gear  73 —as was the case in this mode of carrying out the present invention—the rotation torque of the feed gear  73  is constant so that the load on the feed motor  47  is constant. As a result, it is advantageous in that the feed gear  73  can be stabilized and turned. 
     (10). SECOND MODE OF CARRYING OUT THE PRESENT INVENTION (FIG.  27  THROUGH FIG.  29 ) 
     A second mode of carrying out the present invention is indicated in  FIG. 27  through  FIG. 29 .  FIG. 27  is a partial lateral view of the nail connecting body N.  FIG. 28  is a sectional view of  FIG. 27  seen along XXVIII-XXVIII.  FIG. 29  (A) is a schematic diagram indicating the nail connecting bodies N when they are being fed.  FIG. 29  (B) is a view of  FIG. 29  (A) seen along B-B. 
     In this mode of carrying out the present invention, the connecting material S is provided with a substrate S 1  which extends far out in a belt or band shape. Multiple groups of side pieces S 2  which retain the nail n are disposed on both side edges in the length direction of the substrate S 1 . In addition, the outside surface of the substrate  95  and the front end of the side pieces S 2  are set so that they would surround the periphery of the head of the nail n. As a result, the nail connecting body N may be wound exactly in a coil shape without any loss. 
     Then, holes for latching S 3  are placed at a constant pitch on the substrate  95  and the feed gear (sprocket)  73  is engaged with the latching holes S 3 . The connecting material S can be manufactured using a sheet material such as a resinous sheet or a paper. Needless to say, it can also be manufactured from resin by injection molding. Slits can also be disposed on side pieces S 2  to make it easier for the nails n to fall out. 
     (12) THIRD MODE OF CARRYING OUT THE PRESENT INVENTION (FIG.  30 ) 
     A third mode of carrying out the present invention—which is another example of the feeding means—is indicated in  FIG. 30 . This means that when this mode of carrying out the present invention is used, a shaking type pawl  106  is used as a nail feeding means and this is turned in reciprocating movements when the crank board  107  is turned. The crank board  107  may be driven using a motor such as that indicated in the first mode of carrying out the present invention. 
     (11). OTHER 
     The invention in the present application may be realized by using a variety of other modes. For example, the structure and shape of each of the members may be arranged within a range which does not adversely affect the function which is the objective of the invention. Specifically, the head part may be made so that it has a single structure. The member which is used to configure the head part may be made so that it forms an integral piece with the main body (this means that the component member of the main body and the component member of the head part may be made so that they are common). 
     A piezo-electric element which generates power by pressing the nose member to the workpiece may also be disposed at a suitable locations on the head part or the main body, and the electric power generated by this piezo-electric element may be used as a drive source for the feeding means. The feed device may be either a directly driven type without coupling or a rotary type electromagnetic solenoid. 
     An integrated structure made up of a fastener retaining means such as a magazine and a head part is also possible.