DEVICE FOR REMOVING MANDRELS FROM BLIND RIVETS

Abstract

 The invention is a device for automatic removing mandrels from blind rivets comprising a guide tube (T) and a container (Z), wherein a clamp (K) is provided at one end of the guide tube (T), the guide tube (T) extending at the opposite end into the container (Z), wherein the guide tube (T) is longitudinally movable relative to the frame (R).

Description

Technical Field

[0001] The invention relates to a device for removing mandrels from blind rivets comprising a guide tube and a container, wherein a clamp is provided at one end of the guide tube, the guide tube extending into the container at the opposite end, the guide tube being longitudinally movable relative to the frame.

Background Art

[0002] When riveting with blind rivets, it is always necessary to remove the torn-off mandrel from the mouth of the riveting gun. If the mandrel is not removed, the mouth of the gun may become clogged and the mandrel may enter into the container. This could cause clogging or damage to the guide and thus the entire rivet gun. From a manufacturing point of view, it is unacceptable for a detached mandrel to fall out of the rivet gun mouth. It is known in the prior art, for example in US8091195 or US20130149049, that the removal of the mandrel is solved by means of air flowing through a pipe to move the severed mandrel. A similar type of rivet is also the focus of patent US5600878, where the object of the solution is not the handling of the detached mandrel itself, but the patent focuses on the analysis thereof.

[0003] In state of the art battery operated devices, described for example in US8925166, gravity is used to transfer the severed mandrel into the container, i.e. the operator has to bring the riveting device into a vertical position in order to move the mandrel into the container.

[0004] Further, no automated or electromagnetic mandrel removal is used in the current devices often referred to as cordless rivet guns.

[0005] Quite often, a magnetic field is used to retain rivets, for example in US 20060179649A1 (EP 1690613 A1). The systems used in those documents are only functional for shankless rivets, and furthermore, primarily focus only on the initial centering of the rivet relative to the riveting device.

[0006] The solution described in the invention eliminates the disadvantages of existing solutions by removing the practical problem of holding the rivets in all positions in the riveting device prior to actual riveting, and facilitating the automatic advancement of the mandrel through the device mechanism into the container after the riveting process is complete.

Disclosure of invention

[0007] The essence of the invention is a device for removing the mandrels from blind rivets comprising a guide tube and a container, wherein a clamp is provided at one end of the guide tube, the guide tube extending at the opposite end into a container, wherein the guide tube is longitudinally movable relative to the frame. The guide tube is enclosed by an electric coil. The rivet mandrel which is inserted into the mouth of the device is attracted by a permanent magnet, thereby preventing it from falling off and ensuring stabilization before the riveting process begins. After the rivet head is removed, the mandrel is pulled by the permanent magnet into the cylindrical coil area. More than one electric coil can be used to improve the rivet retraction or to control its displacement. The mandrel is also stabilized by the permanent magnet and cannot fall out of the riveting gun. A very short, but high current pulse to the accelerator coil creates an electromagnetic field which superimposes on the magnetic field of the permanent magnet, thus creating a high pulse of force which accelerates the mandrel. If the pulse were too long, the force acting on the mandrel passing through the centre of the coil would reverse its direction and the motion of the mandrel would slow down, since the force in this case always acts in the centre of the coil.

[0008] The invention eliminates the disadvantages of the previously known and conventional solutions in the following:
In pneumatic systems, suction is used to remove the rivet mandrel by compressed air supplied to the riveting gun via a flexible pipe connected to the workplace infrastructure. The invention uses electromagnetic forces fully controlled by an electric current. The riveting gun thus does not need to be connected in any way to other workplace infrastructure.

[0009] In the case of electrical riveting devices, most often battery-powered, there is no provision for moving the mandrel from the mouth to the container. For this movement, for example, according to patent US8925166 and the state of the art, it is necessary to rotate the device to a vertical position and back. Even so, reliable transfer may not occur, for example due to dirt within the guide system or dirt on the mandrel itself. In this case, the mandrel will fall out of the mouth of the device, which may cause damage to the product. The mandrel can also become caught in the guide and cause the gun to gradually clog or even destroy the gun. The use of a permanent magnet ensures that a detached mandrel is captured immediately after the riveting process is completed. The permanent magnet can also be used to hold and stabilize the entire rivet before starting the riveting process.

[0010] The use of a permanent magnet riveting device does not increase the energy consumption of the riveting device. Therefore, it can be used in cordless riveting machines. Compared to pneumatic systems, the solution itself makes installation considerably easier.

[0011] By using the physical principle of electromagnetic acceleration and the possibility of fully automating the mandrel removal process, a significant acceleration of the riveting process is achieved.

[0012] Compared to existing solutions, the riveting device according to the invention is structurally very simple, space-saving and can be implemented directly in the mouth of the riveting device. Its implementation requires only minimal structural or conceptual modifications.

[0013] There are no increased demands on the operator in terms of handling or weight. The increase in the overall weight of the device is minimal compared to existing devices. The automatic mandrel removal also reduces the need to tilt the equipment, which is physically demanding and very non-ergonomic at high riveting cadence.

[0014] In the case of pneumatic systems, the necessary infrastructure, such as compressed air tanks, compressors, etc., must be provided, and changes in the production line must be designed to take this into account. The integration of the electric coil into the riveting machine greatly simplifies the use of riveting technology. The riveting machine is thus fully independent of any infrastructure and can be used regardless of the space involved.

[0015] In order to improve the function of removing the rivet mandrels, it is essential that the electric coil is connected to the component against which it moves. Preferably, therefore, the electric coil is rigidly connected to the guide tube. Alternatively, the electrical coil may be rigidly coupled to the frame. Both of these solutions are advantageous in terms of the function of the riveting device.

[0016] It is also advantageous if the electric coil includes at least one permanent magnet having an axial orientation of magnetization in the direction of the coil and the magnetic circuit. A permanent magnet helps to hold the mandrel before moving it into the container.

Description of drawings

[0017] A front view of the blind rivet mandrel removal device is shown in Fig. 1a, a sectional view of the device is shown in Fig. 1b, and a detailed sectional view of the blind rivet removal device is shown in Fig. 2. Fig. 3a shows a front view of the coil and a side view of the coil housing, Fig. 3b shows a side view of the coil housing and permanent magnet, and Fig. 3c shows a cross-section of the coil housing and permanent magnet.

Description of example embodiment

Example embodiment I

[0018] The device for removing mandrels from blind rivets consists of a guide tube T and a container Z. At one end of the guide tube T there is a clamp K. The opposite end of guide tube T opens into container Z. The guide tube T is longitudinally movable relative to the frame R. The guide tube T is encircled by an electric coil C. The electric coil C is cylindrical. The electrical coil C is rigidly connected to the guide tube T. The electric coil C includes a permanent magnet M which is positioned in front of the coil C towards the mouth of the clamp K. The head H is firmly connected to the frame R. The rivet mandrel, which is inserted into the clamp K of the riveting gun located in the head H of the device, is attracted by the permanent magnet M. This prevents it from falling off and ensures stabilisation before the riveting process begins. After the rivet head has been removed, the mandrel is drawn by the permanent magnet M into the area of the cylindrical coil C by means of a rod O which is sprung by a compression spring P. The mandrel is also stabilised by the permanent magnet M and cannot fall out of the riveting device. The conductor N in the form of a cable is placed in the space between the frame R and the guide tube T.

[0019] A very short current pulse to the coil C creates an electromagnetic field which superimposes on the magnetic field of the permanent magnet M, thus creating a high pulse of force which accelerates the mandrel and delivers it to the container Z.

Exemplary embodiment II

[0020] The device for removing the mandrel from blind rivets comprises a guide tube T and a container Z. At one end of the guide tube T there is a clamp K. The opposite end of guide tube T opens into the container Z. The guide tube T is longitudinally movable relative to the frame R. The guide tube T is surrounded by electric cylindrical coils C and C' housed in a cylindrical sleeve V forming a magnetic circuit. The electrical coils C and C' are rigidly connected to the guide tube T. The electrical coils C and C' are rigidly connected to the frame R. The head H is rigidly connected to the frame R. The electrical coils C and C' include a permanent magnet M. In this exemplary embodiment, several coils C and C' surround the guide tube. The rivet mandrel, which is inserted into the clamp K of the riveting gun located in the head H of the device, is attracted by the permanent magnet M. This prevents it from falling off and ensures stabilization before the riveting process is started. The conductor N in the form of a cable is placed in the space between the frame R and the guide tube T.

[0021] After the rivet head is removed, the mandrel is pulled by the permanent magnet M into the area of the cylindrical coils C and C' by the pull rod O, which is sprung by the compression spring P. The mandrel is also stabilised by the permanent magnet M and cannot fall out of the riveting device. A very short, but high current pulse into the coils C and C' creates an electromagnetic field which superimposes the magnetic field of the permanent magnet M, thus creating a high pulse of force which accelerates the mandrel and delivers it to the container Z.

Industrial applicability

[0022] The device described according to the invention finds its application in the design of electric or battery-powered riveting devices for mandrels made of magnetic materials. In general, however, the invention can be used where it is necessary to provide automatic removal of bodies which react to a magnetic field.

Claims

1. A device for removing mandrels from blind rivets, comprising a guide tube (T) and a container (Z), wherein a clamp (K) is provided at one end of the guide tube (T), the guide tube (T) extending at the opposite end into the container (Z), wherein the guide tube (T) is longitudinally movable relative to the frame (R), characterized in that the guide tube (T) is encircled by at least one electrical coil (C).

2. The mandrel removal device according to claim 1, characterized in that the electrical coil (C) is rigidly connected to the guide tube (T).

3. The mandrel removal device according to claim 1, characterized in that the electrical coil (C) is rigidly connected to the frame (R).

4. The mandrel removal device according to claim 1, 2 or 3, characterized in that the electrical coil (C) comprises at least one permanent magnet (M).

Drawing