Patents Assigned to Hofmann GmbH
  • Patent number: 5067347
    Abstract: In a method and an apparatus for testing a pneumatic tire such as for testing the uniformity thereof, a tire to be tested is inflated to a given pressure and rolled against a test surface at a tire contact patch, and forces and/or moments acting at the contact patch are measured. To at least reduce the period of time required for the tire to warm up for a testing operation, the compressed air used to inflate the tire is heated to a given temperature before being passed into the interior of the tire. The compressed air may be heated as it flows through a supply conduit, under the control of a sensor for sensing the temperature in the tire.
    Type: Grant
    Filed: July 19, 1990
    Date of Patent: November 26, 1991
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Uwe Monch
  • Patent number: 5067348
    Abstract: A measuring apparatus in which a rotary member is mounted and rotated for measurement or testing thereof, with measuring devices including measurement value pick-up structures for periodically detecting varying forces and/or moments caused by the rotating rotary member. The measuring apparatus includes a machine bed which serves as a component for carrying the measuring devices and for mounting the rotary member. The machine bed is in the form of a casting comprising polymer concrete.
    Type: Grant
    Filed: April 19, 1990
    Date of Patent: November 26, 1991
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventors: Gunther Himmler, Uwe Moench
  • Patent number: 5058429
    Abstract: An apparatus for measuring an unbalance of a rotary member, such as an electric motor armature, comprises a rotary member mounting arrangement for rotatably mounting the rotary member for a measurment operation. The mounting arrangement is capable of oscillating movement in a measurement direction. A drive belt for driving the rotary member in rotation bears against the rotor in substantially tangential relationship therewith or passes around the rotor over a small part of the periphery thereof. A measurement transducer detects forces or oscillations produced by the rotation of the rotary member in the measurement direction and outputs a corresponding signal for unbalance measurement. The drive direction of the belt drive in relation to the rotary member is normal to the measurement direction. The measurement direction may be inclined to facilitate fitting the rotary member into and removing it from the mounting arrangement of the apparatus.
    Type: Grant
    Filed: February 13, 1990
    Date of Patent: October 22, 1991
    Assignee: Gebruder Hofmann GmbH & Co. KG Maschinenfabrik
    Inventors: Gunter Fietzke, Richard Muller
  • Patent number: 5051221
    Abstract: A moist mixture of plaster of Paris and fibres is produced due to the fact that before mixing with the fibres, a considerable quantity of water is supplied to the plaster of Paris, which leads to a moisture content of the plaster of Paris of up to 22% by weight (with respect to the dry substance). With this moisture content, the plaster of Paris is indeed no longer stable in storage in an unrestricted manner; however, it remains free from lumps for a certain processing time and can be mixed with the fibres in a high speed, continuous mixer. The moist mixture of plaster of Paris and fibres obtained in this way is intended as an initial product in the manufacture of fibre-reinforced moulded plaster bodies, in particular of fibre-reinforced plaster boards. It contains the water necessary fort setting in the most homogeneous distribution and in a precise dose (FIG. 1).
    Type: Grant
    Filed: February 21, 1990
    Date of Patent: September 24, 1991
    Assignee: Wurtex Maschinenbau Hofmann GmbH & Co
    Inventor: Jorg L. Bold
  • Patent number: 5040413
    Abstract: A process and an apparatus for testing the uniformity of a pneumatic tire such as a vehicle tire provide that fluctuations in tire inflation pressure are measured during a uniformity-testing measuring run in which the tire to be tested is rolled against a test surface under a given loading, with force fluctuations occurring at the contact surface therebetween, and in which a compensation value is formed from the measured fluctuations. The compensation value is combined with the measured force fluctuations thereby to eliminate force fluctuation components attributable to fluctuations in the tire inflation pressure.
    Type: Grant
    Filed: May 10, 1990
    Date of Patent: August 20, 1991
    Assignees: Gebr. Hofmann GmbH, Co. KG Maschinenfabrik
    Inventor: Klaus-Peter Ohms
  • Patent number: 5033302
    Abstract: A mounting stand in a balancing machine mounting assembly includes a stationary mounting block and a mount for a rotary member to be balanced. The mount is supported on the mounting block by two parallel springs capable of oscillating movement in a mounting plane in the measurement direction. The mounting stand further has at least one measurement value pick-up sensor operatively disposed between the mounting block and the oscillatable mount for detecting oscillation of the mount produced by an out-of-balance rotary member and to supply corresponding measurement signals. A rotatable adjusting unbalance weight of a known magnitude is mounted to the oscillatable mount and can be selectively brought into operation to cause oscillatory movement of the oscillatable system, to perform a calibration.
    Type: Grant
    Filed: January 3, 1990
    Date of Patent: July 23, 1991
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Uwe Monch
  • Patent number: 5027649
    Abstract: In a process and an apparatus for testing the uniformity of pneumatic tires, a fluctuation in radial force is measured and subtracted therefrom is a correction value derived from individual rotational truth profiles in respect of the testing drum, in radial planes which are normal to the axis of the drum.
    Type: Grant
    Filed: May 10, 1990
    Date of Patent: July 2, 1991
    Assignee: Gebr. Hofmann GmbH & Co. KG
    Inventor: Gunther Himmler
  • Patent number: 5019017
    Abstract: In a monitoring arrangement for a belt drive in which a torque produced by a drive motor is transmitted by way of an endless drive belt to a rotary member to be rotated, the drive belt is provided in its longitudinal direction with markings which are adapted to be sensed and which are disposed at equal spacings from each other. First and second sensing members are arranged at a given spacing from each other in succession in the direction of travel of the belt and are operable to sense the markings on the drive belt as they move past the sensing members. The sensing members output corresponding sensing signals in response to the markings. A signal evaluation member is connected to the first and second sensing members, for interrelating the sensing signals in respect of time in dependence on the spacing between the first and second sensing members and the speed of movement of the drive belt.
    Type: Grant
    Filed: February 5, 1990
    Date of Patent: May 28, 1991
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Uwe Monch
  • Patent number: 5016470
    Abstract: In an apparatus for testing a motor vehicle tire and in particular for ascertaining characteristic parameters of a bead thereof, the bead of the tire is subjected to stretching by radially outwardly displaceable clamping jaws and the compression force applied to the tire by the respective clamping jaws are measured by force measuring means. Each of the force measuring means includes a respective measuring body in which a force transmission portion carries the actuating force applied to the respective clamping jaw and experiences deformation in consequence of the force. The force transmission portion bears strain gauges to measure the force, and it is supported by resiliently bendable support portions in such as way that the measuring body is substantially insensitive to moments and transverse forces which could result from radial guidance for the clamping jaws.
    Type: Grant
    Filed: July 27, 1990
    Date of Patent: May 21, 1991
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Gunther Himmler
  • Patent number: 4989449
    Abstract: In a method and an apparatus for determining the restoring moment produced by tangential forces in a tire testing operation, a tire to be tested is rolled against a test surface under identical rolling conditions in first and second measuring runs, the second of which is performed with the tire being turned round through 180.degree. from its position in the first measuring run. The restoring moment which is related to the center of the contact surface at which the tire is in contact with the test surface is formed from the restoring moment values which are obtained in the first and second measuring runs.
    Type: Grant
    Filed: January 18, 1990
    Date of Patent: February 5, 1991
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Uwe Monch
  • Patent number: 4980621
    Abstract: A control arrangement for controlling the power supplied to an electric motor connected to a rotary member to drive same in rotation by way of a belt drive, to accelerate the rotary member to a given speed and to brake it in a slip-free manner provides that a signal which is proportional to the speed of rotation of the rotary member is compared to a signal which is proportional to the speed of rotation of the motor. The supply of power to the electric motor is correspondingly controlled in dependence on the result of the comparison operation.
    Type: Grant
    Filed: November 20, 1989
    Date of Patent: December 25, 1990
    Assignee: Gebruder Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Richard Muller
  • Patent number: 4964299
    Abstract: An arrangement for measuring, in a tire testing machine, radial and axial forces at a wheel consisting of a pneumatic tire and a rim. The measuring axle, on which the wheel is rotatably disposed during the measuring run, has two cylindrical axle parts, of which the first, interior axle part is mounted so that it can be moved radially and frictionlessly in a straight line, and the second, exterior axle part, in axial direction, is frictionlessly located on the first axle part. For introduction of the axial forces, a first force measuring device is provided that is connected with a tension-compression rod that is rigidly connected with the second axle part, and for measuring the radial forces, a second force measuring device is connected between the base plate and the first axle part.
    Type: Grant
    Filed: July 15, 1988
    Date of Patent: October 23, 1990
    Assignee: Gebr. Hofmann GmbH & Co. KG
    Inventors: Manfred Maier, Franz Ruppert, Joachim Schwab
  • Patent number: 4955229
    Abstract: A method and apparatus is proposed for determining the uniformity of pneumatic tires. The apparatus has two measuring rim halves between which a tire to be tested can be mounted and rolled along a test drum. The apparatus has a measuring system for measuring force fluctuations resulting from nonuniformities of the tire and for emitting a corresponding signal, and an evaluation system which evaluates tire uniformity by subtracting a correction signal obtained from eccentricities of the measuring rim halves from a measurement signal. In this way, a compensation of the error component in the measurement signal resulting from eccentricity of the rim halves is obtained.
    Type: Grant
    Filed: October 20, 1989
    Date of Patent: September 11, 1990
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Gunther Himmler
  • Patent number: 4941352
    Abstract: In a method and apparatus for mass centering of a rotor, the unbalance of the rotor is measured and the result of the unbalance measuring operation and the weight of the rotor are used to determine the position of the axis of inertia which extends through the center of mass of the rotor, with respect to the axis of rotation thereof. The position of the axis of inertia is marked on an end face of the rotor by a marking tool. For that purpose, to bring the position of the axis of inertia and the marking tool into the appropriate relationship, relative displacement is produced by an actuating means as between the rotor and the marking tool in the radial direction with respect to the axis of rotation of the rotor, with the rotor or the marking tool being guided in the direction of displacement by a guide means disposed at an angle with respect to the axis of rotation of the rotor.
    Type: Grant
    Filed: May 5, 1989
    Date of Patent: July 17, 1990
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Gunter Fietzke
  • Patent number: 4942003
    Abstract: A method and apparatus for continuously producing molded member, especially sheets, from a mixture of gypsum and fibrous material. In a first mixing stage, measured-out quantities of gypsum and fibrous material are thoroughly mixed together, with the dry mixture being weighed and subsequently moistened in a second mixing stage by supplying water thereto in conformity to the weight of the dry mixture. The moistened mixture is subsequently dispersed onto a support to form molded members, with the surface of each molded member being additionally moistened, and the latter then being compacted. To achieve higher strength, the mas flow of the gypsum/fibrous material mixture is divided into independent partial mass flows that are dispersed in layers to form the multi-layer molded member, with each partial mass flow forming one of the layers of the molded member.
    Type: Grant
    Filed: March 3, 1989
    Date of Patent: July 17, 1990
    Assignee: "Wurtex" Maschinenbau Hofmann GmbH & Co.
    Inventor: Jorg Bold
  • Patent number: 4923326
    Abstract: A clamping ring for clamping a member such as a rotor on a shaft comprises a ring member formed by a plurality of ring segment portions which are displaceable relative to each other in the peripheral direction of the ring member, and spring elements disposed in the respective gaps between adjacent ring segment portions, thereby connecting the ring segment portions together. The clamping ring is fitted into an opening in the member such as a rotor, and the clamping action is produced by a variation in the inside and/or outside diameter of the ring member, by virtue of the ring segment portions being displaced relative to each other in the peripheral direction only in the plane of the ring member.
    Type: Grant
    Filed: February 10, 1989
    Date of Patent: May 8, 1990
    Assignee: Gebr. Hofmann GmbH & Co.
    Inventor: Gunter Fietzke
  • Patent number: 4918983
    Abstract: In an apparatus for checking a motor vehicle tire the bead of a tire is subjected to a stretching effect by radially outwardly displaceable clamping jaws, and the compression force applied to the bead by the respective clamping jaws is measured by force measuring means. Each force measuring means comprises a radially movable frame structure in which a central force transmitting portion connected to the respective clamping jaw is supported movably in relation to outer portions of the frame structure by resiliently bendable support portions bearing strain gauges, in such a way that when a tire is clamped by the clamping jaws, the force transmitting portion is displaced, causing deformation of the support portions, such deformation being measured by means of the strain gauges. The force transmtting portion is supported in the frame structure in such a way that it is substantially insensitive to movements and transverse forces which can result from radial guidance for the clamping jaws.
    Type: Grant
    Filed: April 28, 1989
    Date of Patent: April 24, 1990
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Gunther Himmler
  • Patent number: 4916943
    Abstract: An apparatus for monitoring and controlling the tire inflation pressure in a tire testing machine comprises first and second measuring rim portions for mounting a tire therebetween, and a pressure sensor operable to detect the inflation pressure of the tire. The pressure sensor has a pressure-receiving surface which is arranged to directly detect the pressure in the interior of the tire. The pressure sensor rotates with the tire in a tire testing run. A spindle connected to the measuring rim portions and rotatable therewith has conduit means for supplying compressed air to inflate the tire. A control means is operable to close off the conduit means, thereby constituting a closed volume of air defined by the space within the tire, the space between the measuring rim portions holding the tire, and the conduit means in the spindle, that volume of air rotating as a unit with the components defining same, during a tire testing operation.
    Type: Grant
    Filed: July 13, 1989
    Date of Patent: April 17, 1990
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventors: Gunther Himmler, Werner Lehr
  • Patent number: 4917839
    Abstract: A method for continuously producing molded members. Prior to dispersing the material for the molded members onto the molding belt, the edge zones of the molding belt are covered by protective belts that move along with the molding belt. This prevents the edge zones of the molding belt from getting very dirty.
    Type: Grant
    Filed: June 6, 1988
    Date of Patent: April 17, 1990
    Assignee: "Wurtex" Maschinenbau Hofmann GmbH & Co.
    Inventor: Jorg Bold
  • Patent number: 4905515
    Abstract: A device for measuring rotor imbalance of a rotor is disclosed. The rotor shaft housing support for the shaft for a rotor to be balanced in a machine includes two pairs of springs disposed in two parallel planes. Each pair of springs consists of two parallel bar or rod springs that support the rotor shaft housing support in a plane of oscillation coincident with the shaft of the rotor on the machine stand in such a way that it oscillates. Each of the two bar or rod springs of each pair of springs forms part of a single-piece frame. Mounting strips are attached to the machine stand and to the rotor shaft housing.
    Type: Grant
    Filed: May 13, 1988
    Date of Patent: March 6, 1990
    Assignee: Gebr. Hofmann GmbH & Co. KG Maschinenfabrik
    Inventor: Gunther Himmler