Metal working – Means to assemble or disassemble – Overedge assembling means
Reexamination Certificate
2000-08-18
2002-04-23
Jones, David (Department: 3725)
Metal working
Means to assemble or disassemble
Overedge assembling means
C029S243525, C072S391400, C072S391600, C072S453170
Reexamination Certificate
active
06374474
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for setting two-part fasteners, in particular blind rivets in which for setting a first part has to be pulled while a second part is held up, with a housing, a feed appliance on the housing to transfer a fastener into the housing through an orifice in the housing, an abutment which holds the second part during the setting process and a pulling device for pulling the first part during the setting process, the pulling device having a gripper at an open end of a pulling element which cooperates with a pulling piston which is movable forwards and backwards along an axis of the housing in a first chamber, wherein the pulling element opens the orifice to transfer a fastener.
Devices for setting two-part fasteners, in particular blind rivets, in which for setting a first part has to be pulled and a second part held, which devices have a housing, an abutment which holds the second part during the setting process, and a pulling device for pulling the first part during the setting process, which has a gripper at an open end of a pulling element which cooperates with a pulling piston which is movable forwards and backwards along an axis of the housing in the first chamber, are known. A device of this kind is described, for example, by EP 0 468 717. The feed of a two-part fastener is carried out manually in this device. Putting individual fasteners on to a device of this kind is relatively time-consuming. The use of a device of this kind is particularly disadvantageous for serial manufacture of products.
This problem has already been recognised. U.S. Pat. No. 4,628,722 describes a device for setting two-part fasteners, in particular blind rivets, in which for setting a first part has to be pulled and a second part held. The device has a housing and a feed appliance on the housing to transfer a fastener into the housing through an orifice in the housing. To achieve transfer of the fastener the pulling element has to be pulled back out of a setting position far enough to open the orifice.
The device has two pistons arranged behind one another, a pushing piston and a pulling piston, which are movable forwards and backwards along an axis in a common cylinder. The pushing piston is connected to a cylindrical pushing member. The pulling piston is connected to a cylindrical pulling element. The pulling element extends into the pushing member.
To set a fastener a pressure medium is introduced between the pushing piston and the pulling piston, so the two pistons move away from one another in opposing directions inside the cylinder. The pushing member herein exerts a pressure on the second part of the fastener, while the pulling element pulls on the first part of the fastener. After setting of the fastener has been carried out, a new fastener is put on the device.
For this purpose the pushing piston is impinged with a pressure medium, the pressure medium flowing out of the cylinder between the pistons, so the pushing piston is brought to rest against the pulling piston and the two pistons are driven into a final position in which the orifice is opened for the transfer of a fastener.
To position the two pistons for a further setting process the part of the chamber adjoining the pulling piston is put under pressure while the fluid with which the pushing piston has been impinged is pressed out of the cylinder by the movement of the two pistons. Once the two pistons have taken up a defined position inside the cylinder, the pressure medium is introduced between the pushing piston and the pulling piston, wherein the fluid acting on the pulling piston flows out of the part of the chamber adjoining the pulling piston.
Based on this, the object of the present invention is to develop further the known device for setting two-part fasteners, in particular blind rivets, in such a way that it is more simply designed in construction.
SUMMARY OF THE PRESENT INVENTION
The device according to the invention for setting two-part fasteners, in particular blind rivets, in which for setting a first part has to be pulled and a second part held, has a housing and a feed appliance arranged on the housing by which a fastener is transferred into the housing through an orifice in the housing. The device further has an abutment, which holds the second part of the fastener during the setting process and a pulling device pulling the first part of the fastener during the setting process, the pulling device having a gripper at an open end of a pulling element, which cooperates with a pulling piston which is movable forwards and backwards along an axis of the housing in a first chamber by means of an actuating unit, the pulling element opening the orifice for the transfer of a fastener. The device according to the invention is characterised in that the pulling element extends through the setting piston and the pulling piston and the pulling element are movable relative to one another along the axis, the pulling element has a piston at the end opposed to the pulling device, a second chamber with variable volume is provided, limited by a casing, the piston and the pulling piston, and a third chamber with variable volume is provided, limited by a wall and the piston. A compressible medium is provided in both the second and the third chamber with variable volume.
By means of this configuration of the device according to the invention it is achieved that it is more simply designed in construction. The device also enables easier assembly thereof, as relatively few parts are necessary to produce the device.
Reduction of the components of the device also brings an improved ability to handle the device, if it is a hand-actuated device. The ability to handle the device is also improved by the fact that the device is relatively light, so the person operating the device is prevented from becoming tired while using it.
During the setting process the pulling piston is displaced away from the abutment along the axis of the housing in the first chamber. Displacement of the setting piston is carried out by means of an actuating unit. The path by which the pulling piston is displaced in the direction of the second chamber with variable volume preferably corresponds to the path which is necessary for performing the actual setting process. With the movement of the pulling piston the pulling element, which has gripped the first part of the fastener with a gripper, exerts a tensile force on this first part. If this first part is a mandrel shank of a blind rivet, the pulling piston, and thus also the pulling element, is pulled in the direction of the second chamber with variable volume for sufficient time for the mandrel shank to break.
A further process follows the actual setting process, in which the pulling element is moved away from the abutment inside the housing sufficiently for the pulling element to open the orifice, through which a further fastener can be loaded into the housing. This opening is achieved in the device according to the invention as follows: during the setting process there is a compression of the medium present in the second chamber with variable volume, so the pressure inside the second chamber rises. This rise in pressure effects an increasing axially directed force on the piston, the direction of which corresponds to a tensile force, so the pulling element is further displaced axially. The volume of the third chamber is decreased because of the movement of the piston. This leads to a rise in pressure of the compressible medium present inside the third chamber. A force of pressure of the medium of the third chamber acts on the front face of the piston opposed to the pulling piston. This force of pressure is opposed to the force of pressure of the medium of the second chamber.
The piston can be axially displaced by the force of pressure of the medium of the second chamber until a balance of forces of the forces of pressure applied to the piston occurs. This is preferably the case when the orifice has been opened by the pulling element.
According to an advantageous des
Emhart LLC
Jones David
Murphy Edward D.
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