WO2009072836A2

WO2009072836A2 - Electric apparatus for riveting

Info

Publication number: WO2009072836A2
Application number: PCT/KR2008/007203
Authority: WO
Inventors: Soo Il Lee
Original assignee: Soo Il Lee
Priority date: 2007-12-06
Filing date: 2008-12-05
Publication date: 2009-06-11
Also published as: KR20090059461A; WO2009072836A3; KR100980088B1

Abstract

The electric riveting apparatus of the invention consists of the following items. First, the rear rotary part, connected to a motor and capable of rotating in both the forward and reverse directions, has the connection part formed with a thread or helical groove in the axial direction of the rivet. Second, the front rotary part, installed in the housing, is designed to transfer the rotary force to the blind rivet. Third, the movable mandrel part, which not only has the rear end formed with a screw connection part for screw jointing with the connection part, but is also installed in a manner which allows it to rotate jointly with the front rotary part while staying in the front rotary part, depending on the rotary movement in the front rotary part. This part is also installed in a manner allowing it to slide in the axial direction of the rivet, and has the mandrel part to hold the rivet mandrel of the rivet at the front end. Fourth, the clutch part, which is installed in a way that allows it to move between Position 1 and Position 2 within the housing. Sixth, the clutch part, which can be released from the front rotary part, when in Position 1, to allow the front rotary part to rotate, and can also be connected to the front rotary part, when in Position 2, to prevent the front rotary part from rotating.

Description

[DESCRIPTION] [Invention Title]

Electric apparatus for riveting [Technical Field]

The invention relates to the electric riveting apparatus, particularly one which can allow the blind rivet to be inserted and fastened into the nozzle of the electric apparatus, before making a jointing hole through more than 2 plates to be jointed and pulling the rivet mandrel by the pulling chuck in order to expand the tubular shaft of the rivet, consequently jointing the plates. [Background Art]

A rivet is commonly regarded as a mechanical component, designed to overlap and joint more than 2 members through a process of making a hole through plates to be jointed, inserting a rivet, forming a stopper (in other words a fixing part) by using a hammer or other mechanical equipment, in order to complete the rivet jointing. The riveting, in which the rivet jointing is made, is performed mostly manually, causing the work process to be complex and highly dependent on the operator's dexterity in terms of the defective rate.

So there have been various types of rivets recently being developed to make riveting work convenient and efficient. One of the rivets already developed is the blind rivet, which is a representative case.

A blind rivet commonly comprises not only the rivet mandrel, which has a head, a rivet body, and a breakable groove, but also the outer tubular part which includes deformable tubular body and a flange. In order to fasten a blind rivet, a jointing hole needs to be made through more than 2 plates overlapped, and then the head of the blind rivet needs to be inserted through the hole made until the flange contacts the plate. Then a particular tool needs to be used to pull the rivet mandrel to expand (deform) the end part of the deformable tubular body. At the last stage of the expanding of the deformable tubular body, the rivet body is breaking apart from the rivet mandrel, at the point of breakable groove, while completing the rivet jointing.

However, such riveting work needs a tool for drilling work and also another tool for pulling the rivet mandrel, which, consequently certainly requires separate additional work of making a hole through the abutted plates in advance before the riveting work.

While it is more convenient to use the blind rivet for the riveting work, compared with manual work for conventional riveting work, the inconvenience in making the jointing hole manually still remains.

[Disclosure]

[Technical Problem]

In order to resolve the existing problems, the invention has the purpose of providing an electric riveting apparatus that can perform, using a blind rivet for plates to be jointed, the continuous drilling prior to riveting and the riveting work with one tool.

The invention also has the purpose of providing an electric riveting apparatus that can perform the drilling and riveting work with one tool, using a blind rivet, and the continuous removal of the remaining rivet body in the apparatus.

[Technical Solution]

In order to achieve the purpose mentioned above, the electric riveting apparatus of the invention characteristically comprises the following. First, the housing. Second, the motor, installed within the housing, capable of rotating in both the forward and reverse directions. Third, the rear rotary part, connected to the motor and capable of rotating in both the forward and reverse directions, also having the connection part with a thread or screw groove formed at the side wall in the axial direction of the rivet. Fourth, the front rotary part, installed within the housing, designed to transfer the rotary force to the blind rivet. Fifth, the movable mandrel part (movable mandrel), which has the rear end formed with a screw connection part for screw jointing with the connection part, and which is installed in the front rotary part in manner allowing it to rotate together with the front rotary part or allowing it to slide in the axial direction of screw depending on the state of movement of the front rotary part, and which has the mandrel chuck to hold the rivet mandrel of the rivet at the front end. Sixth, the clutch part installed in a manner allowing it to move between Position 1 and Position 2 within the housing, released from the front rotary part when in Position 1, in order to allow the front rotary part to rotate and connected to the front rotary part when in Position 2, in order to prevent the front rotary part from rotating.

For the invention, the uni-directional bearing can be added to hold and prevent the front rotary part from rotating when the motor moves in the reverse direction.

For the invention, the movable mandrel part can comprise the cylindrical front-end cap designed to provide a limited space at the front end to prevent the mandrel chuck from ejecting forward, the mandrel rear part, connected and fastened to the rear end of the front-end cap, which has the screw connection part, while the mandrel chuck, equipped with multiple compression pieces contracting toward the axial center, can be installed within the front-end cap. Additionally, the mandrel spring can be installed between the mandrel rear end and the mandrel chuck, to push the mandrel chuck toward the limited space at the front end, while the mandrel spring can be compressed by external force.

For the invention, the front rotary part is tubular on the whole, while some span of the side wall has a slit part in which the slit is formed in the axial direction of rivet mandrel. The movable mandrel has the projecting tip formed at the external side for the insertion into the slit, allowing the movable mandrel to transfer the rotary force to the front rotary part when the clutch is in Position 1 when the motor is in the forward rotation, while allowing the movable mandrel to slide toward the front with the guiding help of the slit and the projecting tip when the clutch is in Position 2. For the invention, the front-end tip can be installed in a manner that allows the rivet mandrel to enter and exit at the front end of the front rotary part and also reduces the pressure necessary for the compression pieces of the mandrel chuck to hold the rivet mandrel due to the pointed protrusion at the front- end tip.

For the invention, it is recommended that when there is a front-end tip with a hole formed to allow the entrance and exit of the rivet mandrel (more particularly, rivet body), the hole of the front-end tip needs to be designed in the size and form corresponding to the size and form of the cross-section of the rivet mandrel, allowing the front-end tip to be replaced depending on the kind of the rivet to be used.

For the invention, the forward and reverse selector can be installed to generate the signal to allow the motor to shift from the forward to the reverse direction when a hole is made for the blind rivet by the drill bit formed at the end of the rivet, while the rivet mounted within the front rotary part and the motor rotate in forward direction. Another forward and reverse selector can be installed to generate the signal to change the direction of the motor from the reverse to the forward direction when the riveting work is completed as the blind rivet is pulled and the rivet mandrel is broken apart.

For the invention, the clutch part can comprise the fixed part located at a certain position within the housing and the movable part which can continue to function while sliding within a certain span between Position 1 and Position 2 of the fixed part. The movable part can be formed in a manner that when the movable mandrel part is positioned at the farthest front end, the movable part moves into Position 1 while being released from the front rotary part in order to allow the front rotary part to turn, and when the movable mandrel part is positioned at the farthest rear end, the movable part is connected to the front rotary part in order to disallow the front rotary part to turn.

For an example, when the front rotary part is tubular on the whole, and some span of the side wall has the slit formed in the axial direction of rivet mandrel and the movable mandrel part has the projecting tip formed at the outer side for the insertion into the slit, the movable part can be pushed by the projecting tip to Position 1 as the movable mandrel moves from the rear end to the farthest front end, while the movable part is pushed by the projecting tip to Position 2 as the movable mandrel part moves from the front end to the farthest rear end.

When the forward and reverse selectors are installed to set the motor direction, the respective forward and reverse selector detects the position of the movable mandrel to allow the movable part of the clutch to shift in positions, while simultaneously allowing the motor to change in the rotary directions, consequently allowing drilling, pulling, and rivet ejecting to be performed in a continuous manner.

[Advantageous Effects]

As a result, when carrying out riveting work using blind rivets to joint more than 2 plates, which are hard to weld for a joint because the plates are very thin, or non-metal or made of resin, the invention can help eliminate the inconvenience and reduce the time needed to use a drilling machine first to make a hole through plates and inserting a rivet, and then to alternate between hand tools or various machines for the riveting work.

In addition, the invention has the advantage of enhancing convenience and reducing time for the works, as the mandrel chuck does the pulling after the riveting work using blind rivets is completed and the remaining part of the rivet mandrel is automatically ejected. [Description of Drawings]

Drawings 1 and 2 show the front view and sectional views of the drilling and pulling stages performed according to a practical application of the invention.

Drawing 3 shows the front view of the rivet mandrel inserted and fastened into the movable mandrel according to a practical application of the invention,

Drawing 4 shows the partial front view of the forward and reverse selector according to a practical application of the invention.

Drawing 5 shows the partial side view, from the rear, of the clutch part according to a practical application of the invention.

Drawing 6 shows the vertical and cross-sectional views of the blind rivet in relation to the invention. [Mode for Invention]

The following makes reference to the drawings and the detailed illustration of the invention, to help with the practical applications of the invention. Drawings 1 and 2 show the designing of the electric riveting apparatus for the practical application of the invention. As shown in the practical application of the invention, the electric riveting apparatus consists of the body part (100) and the handle part (10) formed in the shape of a pistol, just like the electric drilling machine commonly used. As part of the pistol shape, the barrel part of the body part (100) has most of the components installed in order along the common axial direction (along the length of the barrel). The motor (110) and the transmission (120) are installed at the rear side of the barrel, and the control devices including the handle part (10) are installed at the handle (10).

In the more detailed illustration of the formation, the forward and reverse directional motor is located, within the pistol shape, at the farthest rear side of the body part (100), which is, in other words, at the rear side with a comparative distance from the barrel.

The rear rotary part is tubular and has the helical groove around the internal wall of the tube (cylinder), and is still capable of rotating even when the external wall is supported by the bearings.

The front rotary part (150) is tubular on the whole or cap-shaped with a front side partially closed, and comprises the rear-end part (151) and the front-end part (155). Between the front-end part (155) and the rear-end part (151), some span of the side wall has a slit formed where the slit (159) is formed in the axial direction of the rivet mandrel. The end of the front side of the front-end part (155) is partially closed by the front-end tip (157). The front-end tip (157) has a hole at the center, with the size and form corresponding to the rivet mandrel to allow the rivet mandrel (26) to enter and exit. The front-end tip (157) can come in various types in order for it to be replaced and used to provide a hole corresponding to the size and form of the cross-section of the rivet mandrel. In other words, the front-end part (155) has a front-end tip which is connectable and replaceable easily. When a blind rivet with the mandrel of a larger size is used, a front-end tip with a smaller hole can be removed from the front end of the front-end part and replaced with a front-end tip (157) of a larger size using a screw connection or socket connection. The rear-end part of the front-end tip (157) is designed to protrude around the hole, with an obtuse but still pointed angle backward. O

The front rotary part (150) is supported by the supportive bearings (171, 175) fixed to the adjacent housing (40), and is still capable of rotating. Some of the bearings supporting the front rotary part (150) consist of the uni-directional bearing (173), such as the clutch bearing, allowing the front rotary part (150) to rotate in the forward direction while not allowing it to rotate in the reverse direction. The uni-directional bearing (173) is commonly installed between the housing and the front rotary part, consequently allowing the housing (40) to support the front rotary part (150). But the direct connection of the uni-directional bearing (173) to the housing is not always necessary.

Within the tubular front rotary part (150), the movable mandrel (160) is installed in a manner that allows it to move in the direction of the rivet mandrel. The movable mandrel (160) consists mainly of the rear end of the mandrel part (161), the front-end cap (165), and the mandrel chuck (167) as well as the mandrel spring (163), both installed inside the front-end cap (165). The rear end of the mandrel part (161) consists of the body (16Id); the connection part (161a), which is located at the front side of the body and connected to the front-end cap (165); and the projecting tip (165c) projected at the external side for the insertion into the slit (159) at the front rotary part (150). The screw connection part (161c), which is tubular and located at the rear side of the body, has the thread on the surface and connects to the helical groove formed at the internal wall of the cylindrical rear rotary part (140).

Roughly the shape of cylinder or ideally a circular cylinder shape, the front-end cap (165) allows the blind rivet body (26) to go through the farthest front end of it for the insertion. At the part after the farthest front end where the rivet body (26) is inserted, there is the tapered span (165a), where the inner diameter grows wider and the side wall grows thinner. Instead of the tapered span, a short span with a narrow diameter of cylinder can be formed in a simple neck shape at the farthest front end of the front end-cap (165) The connection part (161a) of the rear-end part (161) of the mandrel is pressured and fixed into the opening formed at the rear end of the front-end cap (165). Fixation can be made through a simple socket method, while for easier fastening, the connection surface can have a groove and protrusion like mutually engaging cogwheels.

Referring to Drawing 3, the mandrel chuck (167) has multiple compression pieces (167a), which installed at the front side of the mandrel chuck body (167b), allow the rivet body (26) to be inserted and released when the compression pieces open outward, and also allow the rivet body (26) to be solidly fastened when they contract inwards. The compression pieces, in normal conditions, have the tendency to contract inwards due to elasticity. When the movable mandrel (160) is pushed toward the front side within the front-end cap (165), the compression pieces (167a) are inserted through the tapered span (165a) of the front-end cap. Between the mandrel chuck (167) and the connection part (161a), the mandrel spring (163) is installed in a shape of compression coil spring in order to push the body of mandrel chuck (167b) and the compression pieces (167a) toward the front side within the front-end cap (165). Within the front end of the front-end cap, the rivet body can be easily inserted and fixed through the compression pieces, which are wedged to open somewhat outward by the protrusion pointed backward, at the front-end tip (157) formed at the front-end part (155) of the front rotary part. The compression pieces are designed with a gentle slope in order to allow the rivet body to be easily inserted through the area in contact with the rivet body. In these conditions, the compression pieces can just hold the rivet body by exerting a certain level of pressure sufficient enough only to prevent the rivet body from sliding.

At the pulling stage to form a riveting, as the rivet body (26) is pushed backward by the force of the motor and the whole movable mandrel (160) is released from the front-end tip, the compression pieces (167a) of the mandrel chuck are freed of the force which would make them open outward, resulting in a more solid fastening of the rivet body already inserted. Within the front end of the front rotary part (150), the front-end tip (157) is installed not only to allow the entrance of the rivet body (26), but also to provide a protrusion pointed backward to reduce the pressure necessary for the compression pieces (167a) to hold the rivet body. Therefore, in the mode of forward rotation, the compression pieces just hold the rivet body while the front-end tip mainly transfers the rotary force to the rivet body. But taking into consideration that in the pulling stage, the compression pieces are required to solidly hold the rivet body, it is recommended for the multiple compression pieces (167a) to have the polygon cross-section, at the interface with the rivet body, which can consequently correspond to the cross-section of the rivet body when he multiple compression pieces hold the rivet body.

The clutch part (130) consists not only of the fixed part located at a certain position within the housing (40), but also of the movable part which still can function while being capable of sliding within a certain span between Position 1 and Position 2 of the fixed part. In order to help the movable part move between Position 1 and Position 2, the fixed part (131) has an installed ball part, in which the ball (1315) is installed and designed to project from the surface of the fixed part toward the inside. The installed ball part is designed in the following manner. The compression coil spring (1313) is embedded into the groove (1311), with a certain diameter, formed at a certain position of the fixed part (131). The ball (1315), with a diameter nearly similar to the diameter of the groove (1311), is placed onto the spring (1313), which is adjusted in length and elasticity to force the ball to project out of the groove. The ring (1317), with a diameter smaller than the diameter of the ball, is installed onto the ball (1315) at the starting part of the groove, in order to prevent the ball from ejecting from the groove (1311). Onto the internal surface of the fixed part, the movable part (133) is installed in a way that allows it to slide along the internal surface of the fixed part in the axial direction of the rivet mandrel. A guiding device can be installed by using a groove and rib on the interfacing surfaces, in order to allow only sliding in axial direction to take place. For the additional purpose of functioning as the guiding device or regardless of the guiding device, the surface of the movable part (133) that interfaces the fixed part (131) can have both the settling grooves (1331, 1333) and the connection part (1335) between the settling grooves.

The two settling grooves (1331, 1335) are located with a certain distance between themselves in the axial direction of the rivet. The size of each settling groove corresponds to the size of the projected part of the ball from the installed ball part on the surface of the fixed part, so when the projected part of the ball is placed onto the settling grooves, the movable part and the fixed part are mutually positioned against each other unless there is external impact or force applied.

However, any external impact or force exerted onto the movable part (133) could force the movable part (133) to move, as well as force the ball (1315) to move from a settling groove into another one. As the ball is forced by the spring (1313) to project out of the settling groove as much as possible, the movable part (133) cannot be stably positioned against the fixed part (131) along the transition span, which has a shallower groove or no groove at all, while continuing to move, until settling onto one of the two settling grooves.

The front-end rib (1334), at the front end of the movable part, (131) has the gear-formed part (1339) at the rear side. While at the rear end of the front-end cap (165), the front rotary part (150) has the flange, whose front side has also a gear-formed part corresponding to the other gear-formed part (1339). Consequently in Position 1 when the movable part is moved to the front side, the gear-formed parts (1339, 1551) are free of each other, allowing the rotary force of the motor (110) to transfer through the movable mandrel (160) to the front rotary part (150), which then turns jointly with the movable mandrel (160). But in Position 2 when the movable part is moved to the rear side, the gear-formed parts (1339, 1551) interlock with each other, and consequently the clutch part (130) holds the front rotary part (150) from rotating.

At the barrel part of the front side of the pistol-shaped housing (40), the forward and reverse selector (180) can be installed to perform the automatic shift in the rotation direction of the motor as well as to function as a sensor, as illustrated in Drawing 4. The forward and reverse selector may consist of the contact end (181), the spring (183), the movable contact (185a), the stopper (185b), the movable axis (185), the fixed contact (187), the internal case (189b), and the external case (189a). When the drilling is completed using the blind rivet, the electric rivet apparatus moves toward the plates to be jointed until the contact end (181) reaches the plate (30). When the contact end (181) moves backward despite the pressure of the spring (183), together with the movable contact (185a) which is connected to the contact end (181) by the movable axis (185), until reaching the fixed contact (187) to allow the electricity to go through, the forward and reverse selector is turned on.

When electric current flows, the signal of the current is registered into a controller, which is designed to control the motor (not illustrated), in order to make the motor shift in the rotary direction. When the electric riveting apparatus finishes the riveting by pulling the rivet body, and moves away from the plates (30) after the rivet mandrel is broken, the spring (183) is back into the original shape and pushes the stopper (185b) of the movable axis (185) toward the external case (189a), while also pushing the movable contact (185a) and the contact end, as both are fixed to the movable axis (185), toward the front side. The movable contact (185a) is free of the fixed contact of the internal case (189b), consequently tuning the selector off.

When the forward and reverse selector is turned on, a pulse signal is generated once, regardless of whether the selector's contact is turned off. The pulse signal will electronically work on the motor controller to make the motor shift in the reverse direction. It is necessary for the forward and reverse selector to be turned off, in terms of the turned off selector providing the condition necessary for a pulse signal to be generated through the components, including the condenser, on the circuit, when the selector is turned on.

For the practical application, there is an additional forward and reverse selector (190), which can function when the clutch part (130) is shifted into Position 2. The additional forward and reverse selector (190) consists of components similar to those of the forward and reverse selector (180) installed at the front end of the housing (40). When the motor (110) is in the reverse direction, the projecting tip (161b) of the movable mandrel (160) moves backward and pushes the rear rib (1336b) of the removable part (133) of the clutch part to the rear side. Then as the movable part (133) shifts into Position 2 and pushes the rear to the contact end of the forward and reverse selector, the contact turns the selector on. The generated pulse signal is transferred to the controlling part of the motor (110) to make the motor (110) shift to the forward from the reverse direction.

The following shows how the riveting work is performed by using the blind rivet in the practical application of the invention.

First, the operator places the rivet body (26) of the rivet (20) through the front-end tip (157) into the compression pieces (167a) of the electric riveting apparatus. It is difficult to place the rivet mandrel into the compression pieces because the compression pieces are originally inclined to contract toward the center due to elasticity. But as the mandrel spring (163) pushes the mandrel chuck (167) toward the front end of the front-end cap (165), which is, in other words, the part with the narrower diameter of the tapered span (165a), the compression pieces open outward a little bit due to the rear end of the front-end tip (157), allowing the rivet mandrel to be placed easily into the compression pieces.

When the rivet body is placed into the mandrel chuck, the operator releases the rivet body and the mandrel chuck stays at the front side after being pushed by the mandrel spring (163). Within the front end of the front- end cap, the rivet body is fastened into the compression pieces, in other words, into the mandrel chuck. Then the obtuse protrusion, at the rear end of the front-end tip (157), touches the compression pieces (167a), so the rivet body (26) is not solidly fastened into the compression pieces (167a) of the mandrel chuck (167), but rather is fastened just enough to slide in the axial direction when a force is applied in the axial direction of the rivet mandrel. When in the forward rotation, the rivet body (26) receives the rotary force from the front-end tip (157) with a hole corresponding to the rivet body and drills through the plates, so there is no need for any solid fastening into the mandrel chuck (167). It is recommended for the compression pieces (167a) to provide a polygon shape in holding the rivet body (26) to prevent the rivet body from idling.

When the motor (110) is made to turn in a forward direction by adjusting the controlling switch (15) of the handle (10), the rotary force of the motor is transferred through the transmission (120) to the rear rotary part (140).

As the rear rotary part (140) turns in a forward direction, the screw connection part (161c) of the movable part, which has the screw connection with the internal tubular side wall of the rear rotary part (140), is moved to the farthest front end, and then is stopped from going further in the axial direction of the rivet, while turning jointly with the rear rotary part (140).

The screw connection part (161c) is connected to the body (16Id) of the rear-end part (161) of the movable mandrel, and the projecting tip (161b), projected from the outside of the body, is inserted into the slit (150) part at the front rotary part (150), and the front rotary part (150) turns jointly. Instead of using the slit (159) and the projecting tip (161b), the polygon shaft and polygon column can be used to replace the cylindrical shaft and the cylindrical column of the mutually corresponding part between the front rotary part (150) and the movable mandrel (160), allowing the sliding movement in the axial direction of the rivet to take place as well as transfer of the rotary force to take place when in the rotation.

Even with some possible difficulties in making it, when the body of the mandrel chuck (167b) can correspond, in a polygon shape, to the front-end cap (165), the possibility of sliding between the mandrel chuck and the front-end cap could be eliminated entirely.

Drawing 6 shows the vertical section of the blind rivet and the cross- section of the rivet mandrel, as both are used for the invention.

The rivet consists of the drill bit (21), the rivet mandrel, and outer tubular part (27), while the rivet mandrel includes the breakable groove dividing the head (23) and the rivet body (26). The outer tubular part (27) is divided into a flange (27a), which functions as a stopper at the rear end as well as forms a pin head when making a hole for the rivet, and a deformable tubular body.

The rivet body, inserted into the mandrel chuck (167) of the movable mandrel (160), is polygon shaped, and the compression pieces also hold the rivet body in the corresponding polygon shape! consequently the rivet body (26) rotates as it receives the partial rotary force of the motor (110).

The front end of the blind rivet (20) is a pointed-shape drill bit (21) made of strong material, which can make it easier to make a hole through the multiple plates to be jointed.

As the drilling proceeds, the head (23) of the blind rivet (20) goes through the plates first, and then finally the outer tubular part; in other words, the flange (27a) formed at the rear end of the outer tubular part (27) touches the plate (30) as the drilling is completed. Then the rivet body (26) is required to be pulled back.

The driving force necessary for pulling back the rivet body (26) can come from the motor (110). First, when the flange (27a) at the rear end of the outer tubular part touches the plate (30), the forward and reverse selector (180) at the front end of the barrel generates the current signal as the contact end (181) and the movable contact (185a) is pushed backward and the movable contact touches the fixed contact (187). In other words, the forward and reverse selector (180) is turned on when the contacts are connected. For this, an adjusting screw, not illustrated, can be added to the forward and reverse selector (180) to adjust the projected level of the contact end (181). The exemplification of the forward and reverse selector design is illustrated in the practical application by Drawings 1 and 2.

When the forward and reverse selector is turned on and the pulse signal generated from it is registered into the control circuit of the motor, the selecting function within the circuit turns the motor in the reverse direction and the rear rotary part (140) shifts in reverse direction accordingly.

But as the front rotary part (150) is not allowed to turn in the reverse direction because it is restricted in the rotary direction by the uni-directional bearing (173), the rotary movement is stopped. As the front rotary part (150) and rear rotary part (140) do not physically contact each other or connect with each other in a manner allowing them to slide against each other, the stopping of the front rotary part does not influence the rotation of the rear rotary part.

Simultaneously, the screw connection part (161c) of the movable mandrel (160), connected to the rear rotary part, slides backward in the axial direction according to the reverse rotary direction of the rear rotary part. As the projection tip (161b) can be guided along the slit (159) part while the front rotary part does not move, the movable mandrel can slide backward within the front rotary part, which does not cause any interference.

Such movement also occurs at the mandrel chuck (167), which solidly holds the rivet body (26), while the movable mandrel moves backward. The head (23), which is the front end of the rivet mandrel, is connected and fastened with the drill bit (21) or the front end of the outer tubular part (27). So when the mandrel chuck (167) moves backward, there is tensile force exerted at the rivet body, resulting in pulling the drill bit and front end of the outer tubular part, while eliminating any pulling force at the flange (27a) at first. The outer tubular part (27), made of comparatively soft metal, is deformed and expanded outward by the tensile force to create a fixing part opposite the flange (27a). While the tensile force remains, as the rivet head cannot go through the hole made through the plates, the tensile force grows at the rivet mandrel, causing the breakable groove, which is comparatively weak, to break apart. Then the riveting is completed and the plates are jointed. But the rivet body (26) still stays within the mandrel chuck (167) of the movable mandrel (160) of the electric riveting apparatus.

As the motor keeps turning in the reverse direction, the movable mandrel (160) keeps moving backward. Then the projecting tip (161b) of the movable mandrel touches and pushes the rear rib (1336) of the clutch part (130) backward. As the movable part moves backward, the gear-formed part (1339) at the front rib (1334) interlocks with the gear-formed part (1551) at the front rotary part.

Simultaneously, the rear rib of the movable part turns on the forward and reverse selector (190), which then transfers the pulse signal to the controlling circuit that controls the rotation of the motor, in order to shift the motor to the forward direction. Then the rear rotary part (140) changes to the forward rotation.

In relation to the fixed part, the movable part can move within a certain scope in the axial direction while unable to turn, so the front rotary part (150) of the movable part cannot rotate, as it is interlocked with the gear-formed part (1339). In contrast to the motor turning in the reverse direction, when the motor rotates in the forward direction, the screw connection part (161c) of the movable mandrel slides forward. When the movable mandrel reaches the farthest front side, the movable mandrel is stopped from going further by the front-end tip (157) of the front rotary part (150). The compression pieces of the mandrel chuck of the movable mandrel are forced open through the hitting of the obtuse projection, pointed backward, at the front-end tip. Then the remaining rivet body can move in the axial direction through the opening. Consequently, the inertia, which forces the movable mandrel to move forwards within the front rotary part, helps the remaining rivet body to move continuously to project almost wholly out of the o

front-end tip or to eject completely from the electric apparatus, even after the movable mandrel is stopped. In the process, the projecting tip (1616) of the movable mandrel touches and pushes the front end stopper (1338) of the removable part (133) of the clutch part forward, so that the gear-formed part (1339) at the front rib (1334) is released from the gear formed part (1551) at the front rotary part (150).

When the forward and reverse selectors (180, 190) are in operation, certain alarm devices which can generate light or sound signals can also be installed together with the forward and reverse selectors to clearly alert the operators that the forward and reverse selectors make the motor turn in the other direction.

Even though not clearly illustrated, a power supply is necessary for the motor to rotate, and the controlling switch (15) is also necessary to allow the motor to receive the power supply and to shift in the rotary direction. It is more convenient when the controlling switch (15) is installed at the handle part (10) on the pistol-shaped housing. While it is sufficient for the power switch or the controlling switch at the handle to provides only an on-and-off function, when taking into consideration the forward and reverse selector, it is still recommended for the controlling switch to provide the forward and reverse selection function due to the possible need for manual operation in case the forward and reverse selector is not provided or not working.

In the practical application detailed above, when the motor turns in the reverse direction, the uni-directional bearing plays a critical role in holding and preventing the front rotary part from turning. Since the clutch part can also play the role of the uni-directional bearing, the uni^¬ directional bearing in the invention is not a must-have component. Without the uni-directional bearing, however, there is a need for a device similar to the forward and reverse selector, which may change the position of the movable part, or for a device which the operator can operate as necessary to move the movable part of the clutch part to perform the demanded function, which means the design might be more complicated.

Even though it is not illustrated, there can be a controlling circuit, including the controller, which can be created on the PCB in order to control not only the forward and reverse direction of the motor, but also the interaction with the forward and reverse selector (180) or the controlling switch (15). As the design of the controlling circuit, in which the forward and reverse selector can make the motor turn in the forward and reverse directions, is available in various configurations from the circuit design department and is also not critical to the invention, the specific practical application of the circuit designing is not illustrated.

The components, including the motor (11), are also fixed within the housing using some fastening devices such as brackets. In the following drawings, the detailed illustrations on how to fix the components, including the motor (11), which would require any fastening within the housing (40), will not be provided because they are available with general technology.

Claims

[CLAIMS]

[Claim 1]

An electric riveting apparatus comprising, a housing, a motor installed within the housing and rotating both in forward and reverse directions, a rear rotary part connected to the motor, rotating in both forward and reverse directions, having a connection part with a thread or screw groove formed at a side wall in an axial direction of a rivet, a front rotary part, installed within the housing, designed to transfer rotary force to the rivet, a movable mandrel, which has a rear end formed with a screw connection part for screw jointing with the connection part and a mandrel chuck to hold a rivet body of a rivet at the front end, and which is installed in the front rotary part in a manner allowing it to rotate together with the front rotary part or allowing it to slide in the axial direction of the rivet depending on a state of movement of the front rotary part, a clutch part installed in a manner allowing it to move between a first position and a second position within the housing, released from the front rotary part when in the first position in order to allow the front rotary part to rotate and connected to the front rotary part when in the second position in order to prevent the front rotary part from rotating.

[Claim 2]

The electric riveting apparatus according to claim 1, wherein the movable mandrel has a cylindrical front-end cap designed to provide a limited space at the front end to prevent the mandrel chuck from ejecting forward, and a mandrel rear part which is connected and fastened to the rear end of the front-end cap and has the screw connection part, and a mandrel spring which is installed between the mandrel rear end and the mandrel chuck to push the mandrel chuck toward the limited space at the front end when the mandrel spring is compressed by an external force, and the mandrel chuck installed within the front-end cap includes multiple compression pieces contracting toward the axial center.

[Claim 3]

The electric riveting apparatus according to claim 2, wherein the front rotary part is tubular on the whole, and a span of the side wall of the front rotary part has a slit formed in the axial direction of the rivet, and the movable mandrel has the projecting tip formed at an outer side and inserted into the slit so that the movable mandrel can transfer the rotary force to the front rotary part when the clutch is in the first position and the movable mandrel can slide forward when the clutch is in the second position when the motor rotate in the forward direction.

[Claim 4]

The electric riveting apparatus according to claim 2, wherein a replaceable front-end tip at the front end of the front rotary part has a hole formed to allow an entrance and exit of a rivet body of the rivet, and the hole of the front-end tip needs to be designed in size and form corresponding to the cross section of the rivet body.

[Claim 5]

The electric riveting apparatus according to claim 1, wherein the clutch part comprises a fixed part located at a certain position within the housing, and a movable part which can move between the first position and the second position of the fixed part, and when the movable mandrel is positioned at the furthest front end, the movable part is placed in the first position, and when the movable mandrel is positioned at the furthest rear end, the movable part is placed in the second position and connected to the front rotary part.

[Claim 6]

The electric riveting apparatus according to claim 5, wherein the front rotary part is tubular on the whole, and a span of the side wall of the front rotary part has the slit formed in the axial direction of the rivet, and the movable mandrel has the projecting tip formed at the outer side inserted into the slit, the movable part can be pushed by the projecting tip to the first position as the movable mandrel moves from the furthest rear end to the furthest front end, while the movable part is pushed by the projecting tip to the second position as the movable mandrel moves from the furthest front end to the furthest rear end.

[Claim 7]

The electric riveting apparatus according to claim 5, wherein a first forward and reverse selector is installed to generate a signal to allow the motor to shift from the forward to the reverse direction when a hole is completed for the rivet, and a second forward and reverse selector is installed to generate a signal to allow the motor to shift from the reverse to the forward direction when the riveting work is completed as the rivet body is pulled and broken apart, and the second forward and reverse selector generates the signal when the movable part changes from the first position to the second position.

[Claim 8]

The electric riveting apparatus according to claim 1, further comprising an uni-directional bearing to hold and prevent the front rotary part from rotating when the motor moves in the reverse direction.