48 results about "Normal force" patented technology

The invention discloses a contact resistance-based method for synchronously measuring normal force and shear force of an interface, which comprises the following steps of: inspired by a yield criterion of material damage, establishing a relationship between normal stress and shear stress of the contact interface, thereby obtaining a relationship between a real contact area of the contact interface and the normal force and the shear force; obtaining the relationship between the contact resistance of the contact interface and the real contact area, and establishing the relationship between the contact resistance of the interface and the normal force and the shear force; according to the geometric deformation relation of the micro-convex bodies on the contact interface before and after the shearing force acts, the relation between the real contact area of the contact interface and the geometric deformation parameters of the micro-convex bodies is obtained, and the relation among the normal force of the contact interface, the shearing force and the geometric deformation parameters of the micro-convex bodies is obtained; and establishing a simultaneous equation set, measuring the contact resistance, and substituting the contact resistance into the equation set to calculate the normal force and the shear force. According to the invention, the normal force and shear force of the interface can be indirectly measured by measuring the contact resistance of the contact interface.

The invention discloses a dam abutment three-dimensional block stability analysis method based on 3DE. The method comprises the following steps: constructing a three-dimensional geologic model in a dam abutment area in 3DE; dividing the three-dimensional block body of the dam abutment into discrete block bodies according to the spatial cutting relation of the structural surfaces; the direction of the intersecting line between the side sliding surface and the bottom sliding surface is defined as the possible sliding direction of the dam abutment three-dimensional block; taking the mass center of each discrete block as a starting point, and drawing a vector along the action direction of each type of load; obtaining resultant force vectors of the corresponding discrete blocks in an absolute coordinate system; determining possible sliding force borne by the dam abutment three-dimensional block and normal force of each sliding surface; the possible anti-sliding force borne by the dam abutment three-dimensional block is obtained. According to the method, the block morphology and the load distribution are visually displayed in a three-dimensional form, the possible sliding direction, the possible sliding force and the possible anti-sliding force of the three-dimensional block of the dam abutment can be automatically determined, the calculation efficiency is improved, and the accuracy of a calculation result is ensured.

A method of analyzing torque and drag of a drill string in a wellbore includes receiving wellbore data including a trajectory of the wellbore, and receiving drill string data for the drill string, at least a portion of the drill string including an inner string positioned inside of the drill string. The method includes generating a virtual wellbore associated with the inner string based on an inner diameter of the drill string and based on the trajectory of the wellbore, and determining a set of inner forces for the inner string including an axial force based on the weight of the inner string and a set of contact forces between the inner string and the virtual wellbore. The method includes identifying a set of normal forces between the drill string and the wellbore based on simulating the inner forces as applied forces to the drill string.

The present application belongs to the technical field of wind tunnel test, and discloses a method for adjusting the loading center of a force applying device of a half-model balance calibration system. The method comprises establishing a balance calibration center; comparing the size of the balance to calculate the displacement amount; adjusting the target position of the normal force applying point; and adjusting the target position of the lateral force applying point. The method takes the initial position state of the reference balance at the initial stage of the construction of the half-model balance calibration system as the reference, uses a laser tracker to determine that the loading center of the force applying device coincides with the calibration center of the initial balance, and records the original positions of the force applying points. During subsequent calibration, the size of the balance to be calibrated and the reference balance is iteratively calculated to obtain the target positions of the force applying points, and then the grating ruler and laser interferometer measurement and manual adjustment by the staff are used to adjust the force applying points to the target positions, so that the balance calibration center of the balance to be calibrated coincides with the loading center of the force applying device, and the calibration data accuracy of the balance to be calibrated is ensured.

The present invention relates to a method for controlling the normal vibration stability of a maglev train based on a transfer function. The steps are as follows: Obtain the mechanical structure parameters and electromagnetic parameters of the linear induction motor for the maglev train, and establish a mathematical model of the normal force of the linear induction motor; Obtain the dynamic model of the medium and low-speed maglev train considering the normal force through the spring-damping coupling model of the medium and low-speed maglev train; Perform Laplace transform on both sides of the obtained dynamic model of the medium and low-speed maglev train considering the normal force; Obtain the transfer function of the normal vibration of the maglev train according to the dynamic model of the medium and low-speed maglev train considering the normal force obtained by the Laplace transform; Perform stability control on the operation of the maglev train according to the obtained transfer function. The present invention solves the problem that the existing dynamic model of the maglev train does not consider the fluctuation of the normal force of the linear induction motor when established, and cannot analyze the influence of the normal vibration of the linear induction motor on the stable operation of the maglev train.

The invention belongs to the field of earth science and engineering geology, and particularly relates to a rock rough interface friction slip test device and test method.According to the rock rough interface friction slip test device and test method, multiple first test pieces are attached to the outer side wall of a test piece, multi-point detection can be conducted on the strain force of the test piece, and the defects of a traditional single or low-density sensing layout are overcome; and the completeness and accuracy of experimental data are improved. The upper shell and the lower shell apply confining pressure to the test piece, and the first force application part and the second force application part are matched to apply normal force and shear force, so that a three-dimensional stress field can be effectively simulated; the temperature changing mechanisms in the upper shell and the lower shell, the second test piece and the third test piece are used for detecting dynamic distribution and micro-fracture evolution of sliding friction heat generation, so that coupling monitoring of multiple physical fields such as sound, heat and strain is realized, and a multi-factor interlaced friction instability process under a real geological condition is effectively simulated; and powerful support is provided for deep exploration of geological disasters and engineering activity mechanisms.

The present application belongs to the field of geotechnical engineering in-situ testing technology, and discloses a kind of in-situ shear test device and test method in field drilling, including ground driving system, drill rod, centralizer and shear probe, ground driving system includes shear loading assembly, tangential pressure assembly and normal pressure assembly, tangential pressure assembly is connected with shear loading assembly by hydraulic line, for driving shear loading assembly to output tangential force;Drill rod bottom end is connected with shear probe, normal pressure assembly is connected with shear probe by hydraulic line, drives shear probe to output normal force;Shear probe is equipped with centralizer, and centralizer is used to contact with the inner wall of borehole;Tangential pressure assembly and normal pressure assembly are all servo motor driven hydraulic equipment, and are controlled by industrial computer;The accurate constant pressure control of normal stress is realized by ground driving system, test is more accurate, and is suitable for soft soil to hard rock extensive stratum, and centralizer can prevent eccentric force from affecting test accuracy.

An actuator assembly comprising first (10) and second parts (20) that are movable relative to each other along at least one movement path M in at least one degree of freedom of movement; an actuator arrangement (40) comprising at least one actuator (40a) configured, on actuation, to cause an actuating force to be applied to the second part so as to move the second part relative to the first part along the at least one movement path within a range of movement; a biasing arrangement (30) configured to: apply, when the second part is positioned relative to the first part within the range of movement and at positions that are located along the at least one movement path and on opposite sides from a set position, a lateral force to the second part acting in a direction along the at least one movement path and away from the set position; wherein at least one common component is configured to apply to the second part both i) the lateral force and ii) the actuating force or a normal force for loading a bearing arrangement (50) that guides the movement of the second part relative to the first part along the at least one movement path.

The invention discloses a design method, a product, a medium and equipment for a buckling-restrained brace frame arranged in a rhombus shape, and belongs to the technical field of civil engineering. The method comprises the steps that S1, mechanical parameters are solved, wherein axial force of two BRBs and counter force of a beam joint are solved; s2, determining a column node normal force balance condition based on the axial force of the BRB; s3, deriving a linear stiffness ratio: solving the linear stiffness ratio based on a column node normal force balance condition and the linear stiffness of the two BRBs; s4, structural analysis and model selection: performing BRB model selection according to the linear stiffness ratio, and determining product parameters through structural analysis; s5, yield force design is conducted, specifically, the cross section area of the core material energy consumption section is determined based on the BRB yield force condition, and then yield force design is achieved according to the linear stiffness relational expression and the comprehensive yield displacement, the ultimate bearing capacity and the ultimate displacement; and S6, determining a material combination according to a design result of S5. According to the invention, the adverse effect of the normal unbalanced force at the node of the buckling-restrained brace frame column arranged in the rhombus shape on the frame column can be eliminated.

This invention provides a human-robot collaborative handling control method, system, and electronic device. It calculates the desired normal force applied by the robot to the target object being handled, and measures the real-time normal force on the target object using sensors. Based on the desired and real-time normal forces, a control normal force to be applied is calculated. Based on a set reference trajectory and the detected external force, a composite acceleration is calculated. The desired trajectory is determined based on the composite acceleration, and an impedance controller obtains an impedance control force based on the external force and the desired trajectory. Combining the control normal force and the impedance control force, the robot's control torque is calculated. This solution considers the influence of external forces while tracking the desired trajectory, thereby achieving the goal of avoiding target deviation while maintaining operational comfort.

This invention discloses a method, system, and medium for measuring stress and earth pressure behind retaining walls / piles under localized overload. Addressing the shortcomings of existing technologies in simultaneously considering stress or earth pressure measurement under localized overload and rotational displacement of retaining walls / piles, this invention first solves the problem of measuring additional vertical stress behind retaining walls / piles under localized overload. The calculation model is constructed by combining theoretical derivation of the mechanical response of a semi-infinite elastic body surface subjected to a concentrated normal force with experimental test data analysis. Secondly, the invention solves the problem of measuring earth pressure behind retaining walls / piles under localized overload. The optimized scheme provides identification schemes for eight measurement conditions under five types of rotational displacement modes of retaining walls / piles, as well as non-limit active earth pressure measurement schemes under each measurement condition. The measurement method of this invention has a clear calculation model, easily obtainable parameters, and high engineering applicability. This invention also provides a force measurement system based on the measurement method and a medium for carrying the measurement method.

The application provides a design method of a U-shaped steel clamp for an aviation wheel, and belongs to the technical field of aviation brake wheels. The method determines the compressive stress of the steel clamp according to the normal force transmitted by the guide rail of the aviation wheel to the steel clamp and the contact area between the guide rail of the aviation wheel and the steel clamp. When the compressive stress of the steel clamp meets the requirements, the dangerous shear cross-sectional area of the steel clamp is determined. Then, the maximum shear stress of the steel clamp is determined according to the dangerous shear cross-sectional area of the steel clamp and the determined normal force. When the shear stress of the steel clamp meets the requirements, the bending modulus of the cross section of the steel clamp is determined. After that, the maximum bending moment borne by the steel clamp is determined according to the determined normal force. Finally, the maximum bending stress of the steel clamp is determined according to the determined bending modulus of the cross section and the maximum bending moment, and whether the maximum bending stress of the steel clamp meets the requirements is determined. The method solves the problem that the U-shaped steel clamp is prone to fracture, resulting in loss of friction torque and functional failure of the rotor assembly.

This invention discloses a finite element simulation method and system for a suspension bridge tower top saddle. The method includes: collecting multiple types of parameters; iteratively solving for tangential and normal forces based on an initial tangential stiffness matrix; calculating the actual contact friction coefficient based on the coupling relationship between temperature and contact normal pressure; calculating a tangential correction coefficient based on the actual contact friction coefficient, the ratio of tangential to normal forces, and the linkage relationship between the saddle geometric parameters; dynamically adjusting the tangential stiffness matrix based on the correction coefficient, the saddle pre-offset, and the synergistic relationship between cable stress; constructing a finite element model and simulating it; and iteratively optimizing until convergence. The system corresponds to the modules described above. This invention optimizes simulation accuracy through multi-factor coupling and linkage, adapting to complex working conditions and providing reliable support for the design and construction of suspension bridges.

The embodiment of the application provides a slope limit equilibrium method based on shear deformation coordination, relates to the technical field of slope stability analysis, and introduces the mechanical concept of shear deformation coordination into the limit equilibrium method, and after the target slope is discretized into a plurality of strips, mechanical calculation is carried out on each strip, the shear force at the bottom of the first strip to the shear force at the bottom of the n-th strip, the normal force at the bottom of the first strip to the normal force at the bottom of the n-th strip, the interstrip shear force and the interstrip normal force are sequentially solved, the H n+1 of the last strip node is obtained, and iteration is carried out to obtain the safety factor F n+1 of the target slope when the condition is met s , which is the safety factor F s of the target slope finally obtained. In the calculation of the interstrip shear force, the method introduces the basic assumption of deformation coordination, combines the calculation of the interstrip force with deformation, has clear physical meaning, avoids the randomness of the interstrip force assumption of the traditional limit equilibrium method, and makes the calculation result more scientific and reliable.

The application discloses a bolted joint normal contact stiffness driven assembly preload and fractal parameter optimization method, and belongs to the field of dynamic characteristic analysis of numerical control machine tools. The method comprises the following steps: a mapping relationship model of the normal contact stiffness of the bolted joint, the normal force, the fractal dimension of the joint surface and the surface roughness parameter is established; the normal contact stiffness under the steady state is taken as the target, and the inflection point is defined as the optimization result of the normal force, the fractal dimension of the joint surface and the surface roughness parameter; a normal force and assembly preload relationship model is established, and an assembly preload optimization method considering the safety factor is proposed; a cutting parameter and joint surface fractal dimension and surface roughness parameter relationship model based on a neural network is constructed, and the cutting parameter is optimized reversely. The application not only optimizes the assembly preload and the surface characteristic parameter from the assembly dimension, but also controls the surface characteristic parameter from the manufacturing angle, and has important engineering value for improving the normal contact stiffness of the bolted joint and the dynamic characteristics of the whole machine.

The utility model belongs to the field of mechanical manufacturing, and relates to a reversely-supported guide rail which comprises a supporting guide rail, a connecting plate, a rolling body, a rolling body supporting device and a magnet device. The supporting guide rail is provided with an upper guide rail surface and a lower guide rail surface. The lower guide rail face is a plane, is parallel to the moving direction of the guide rail and is perpendicular to the direction of positive pressure acting on the guide rail face. The guide rail surface is a bearing surface of opposite force and is also a guide rail surface of a rolling body. A space is formed by the horizontal parts of the connecting plates installed on the two sides of the workbench and the lower guide rail face and used for containing the rolling bodies, the rolling body supporting devices and the magnet devices which are installed on the connecting plates. An air gap is formed between the magnet and the lower guide rail face, the lower guide rail face bears external force through the magnetic force of the magnet, the connecting plate is a force transmission plate for bearing counter force, the magnetic force of the magnet is transmitted to the workbench, and the external force acts on the lower guide rail face of the bearing guide rail instead of pressing the upper guide rail face. The upper guide rail is free of friction and only plays a guiding role. The guide rail can improve the positioning precision and the machining precision of a machine tool.

The invention discloses a normal force adjustable two-dimensional foundation excitation dry friction experimental device, which comprises an optical platform, a vibration exciter and a foundation framework, a two-dimensional translation sliding table is supported on the bottom surface of the foundation framework, a lifting platform is arranged in the foundation framework, a foundation friction plate is fixedly arranged at the top end of the lifting platform, and a vibration exciter is arranged on the foundation friction plate. An elastic supporting friction plate is arranged on the upper side of the basic friction plate, is suspended at the upper part of the basic frame through the stretching of a spring, and forms a friction pair with the basic friction plate; a balance weight disc is fixedly arranged in the middle of the top face of the elastic bearing friction plate. Three-way acceleration sensors are arranged between the top face of the balance weight disc and the bottom face of the base frame and between the lifting platform and the bottom face of the base frame. The two vibration exciters are arranged outside the foundation frame, and an angle of 90 degrees is formed between output ejector rods of the two vibration exciters. According to the invention, the dynamic two-dimensional friction experiment capable of simulating elastic supporting conditions and accurately adjusting normal force can be carried out, so that the nonlinear dynamic characteristics of the friction pair as a complete vibration system can be deeply studied.

A system loosely attaches, and subsequently detachably fixes, panels to substrates with self-alignment of the panels. A clip has a base, arm and bearing surface. A portion of the arm delineates a part of an opening of a pocket with an opening. When not locked, the arm is elastically moveable between a first configuration where the opening has a first size and a second configuration where the opening has a second size. Application of a counteracting normal force to the bearing surface locks the arm in the second configuration. When the arm is locked, the panel is loosely held, free to pivot but with the leading portion of the engagement feature unable to be withdrawn from the pocket. The panel can subsequently be removably locked in place in an assembly of panels.

The invention discloses a force-sensing polishing device supporting revolution and autorotation, which comprises a revolution part and an autorotation part, a spoke type force measuring seat of the autorotation part is fixedly connected with an eccentric seat of the revolution part through a guide screw, and the eccentricity adjustment of the autorotation part can be realized; the small servo motor driving assembly comprises a small servo motor, a mounting seat and a small gear, and is fixed on the outer shaft body through the mounting seat; the pinion is matched with the bull gear to decelerate and drive the autorotation part to form revolution motion of the device; autorotation motion is directly driven by a servo motor through a coupling; strain gauges are attached to spokes of the spoke type force measuring base, and real-time sensing of normal force in the grinding and polishing process can be achieved; the conductive slip ring ensures stable transmission of electric signals of the rotation part in a rotation state. The device is compact in overall structure, has high-frequency and high-precision force sensing capacity, and is widely applied to the field of precision machining of complex free-form surfaces.

An assembly comprising: a first part defining a primary axis; a second part which is movable with respect to the first part; and a third part which is movable with respect to the first and second parts and comprises a first friction surface which is biased against a second friction surface with a normal force. The second friction surface is disposed on one of the first and second parts. The assembly further comprises a first SMA element arranged to drive movement of the third part along a first direction, at least a component of which is perpendicular to the primary axis. The third part is mechanically coupled to the first and second parts such that movement of the third part along the first direction causes movement of the second part relative to the first part along a second direction, different to the first direction. At least a component of the second direction is parallel to the primary axis. The first SMA element is arranged such that contraction of the first SMA element reduces or removes the normal force between the first and second friction surfaces. The assembly further comprises a force-application arrangement configured to: apply a force between the second part and the first part, thereby reducing or removing the normal force between the first and second friction surfaces, and cause movement of the second part along a third direction, at least a component of which is parallel to the primary axis and opposite to the at least a component of the second direction.

The invention discloses a process method for controlling a structured turning tool to machine a roller surface nano-structure through normal force, and belongs to the field of nano-structure machining. Comprising the following steps that firstly, a metal roller 7 is fixed to a roller clamp 6; secondly, the metal roller 7 is subjected to aligning operation; thirdly, the inclination angle of the tool 13 is eliminated; 4, starting to execute a nano machining program; fifthly, the piezoelectric displacement table 10 starts to drive the tool 13 to move downwards to conduct micro-motion feeding; and 6, the metal roller 7 is in a rotating state all the time in the micro-motion cutter feeding process, the cutter 13 and the surface of the metal roller 7 are in a cutting state instead of an impressing state all the time, and therefore the structural quality of the cutter feeding position and the cutter lifting position is guaranteed. And seventhly, the fourth step to the sixth step are repeated, and the large-range nanostructure array can be machined on the surface of the metal roller 7. According to the process method, the normal force of the cutter and the surface of the roller can be controlled so as to accurately control the machining depth, and the cutter can accurately follow the surface of the roller in the turning process.

The invention belongs to the technical field of multi-component aerodynamic load measurement sensors, and discloses a method for calibrating a sheet hinge moment balance with axial force. A special loading device is used in the sheet type hinge moment balance calibration method. The loading device comprises a calibration supporting rod, a calibration connector, a sheet type hinge moment balance with axial force, an adapter connector, a sliding block and a loading head. The calibration method of the sheet type hinge moment balance comprises calibration in the positive normal force direction, calibration in the negative normal force direction, calibration in the positive axial force direction and calibration in the negative axial force direction. Wherein when the normal force direction is calibrated, the sliding block is fixedly connected with the conversion connector, and when the axial force direction is calibrated, the loading head is fixedly connected with the conversion connector. According to the calibration method of the sheet type hinge moment balance, the gravity of the weight is directly applied to the loading device, the balance measurement error caused by the introduction of the friction force of the pulley is avoided, the calibration of the sheet type hinge moment balance with the axial force in four directions is realized, the measurement accuracy of the hinge moment is effectively improved, and the calibration method has practical engineering value.

The invention relates to a microcosmic test device and method for measuring shear friction and anti-torsion characteristics of a microcosmic contact interface. Independent test modules for torsion test and shear test can be realized. The microcosmic test device comprises a support platform, a test unit (a torsion unit and a shearing unit) and a rotating unit. Compared with the prior art, normal displacement, shear displacement, friction coefficient and torsion angle of a contact interface under the single or coupling action of normal force, tangential force, torque and the like at the micro-nano scale are realized, and the relationship between force-displacement and torque-rotation angle is established; the microcosmic contact mechanical properties of a particle aggregate, a particle-plane, a plane-plane, a cemented sample interface and the like can be accurately reflected.

The invention belongs to the technical field of aircraft strength and rigidity design, and particularly relates to a shear deformation component calculation method of a rectangular sandwich panel with four simply supported sides under normal force. The method includes the following steps that firstly, a coordinate system is defined based on the four-side simply-supported rectangular sandwich panel; 2, defining shearing parameters of the four-side simply-supported rectangular sandwich panel structure; 3, establishing an infinitesimal body balance equation; 4, establishing a control equation according to the infinitesimal Hooke's law; and 5, solving the shear deformation.

Friction devices and systems for dissipating energy from a structure are provided. In various embodiments, the friction device may include a first friction assembly including a first plate and a second plate and configured to generate a first friction force by a movement of the first plate relative to the second plate; a first fastener assembly configured to exert a first normal force onto the first friction assembly; a second friction assembly including auxiliary pads and configured to generate a second friction force by a movement of the auxiliary pads relative to the second plate when the auxiliary pads are coupled to the first plate; and a second fastener assembly configured to exert a second normal force onto the second friction assembly, in which energy is dissipated by a total friction force that is a sum of the first friction force and the second friction force and discretely variable.

The application discloses a design method of a blade connecting interface and a hybrid structure fan blade. The design method of the blade connecting interface comprises the following steps: S1, assuming a curve of the connecting interface and obtaining a curve function of the curve, and decomposing external force on the connecting interface into a tangent force function and a normal force function; S2, obtaining an interface shear strength function by using the normal force function; S3, making the tangent force function less than the interface shear strength function, and obtaining a relationship between the external force on the connecting interface and the curve function; S4, obtaining a relationship between an external force load and the curve function; S5, obtaining a specific form of the curve function according to the determined external force load, if the curve form cannot be realized due to various reasons, returning to S1 to start iteration, and if the curve form can be realized, executing step S6; S6, processing a metal leading edge panel and a composite material according to a corresponding form of the connecting interface; and S7, splicing. The force borne by the interface is converted into a tangent force and an interface pressure, and finally the shear deformation or stress of the interface is reduced.

The invention relates to a method of determining a mechanical action torque component at a guide point of a cutting blade (L) for a cutting machine, the cutting blade being guided into a presser foot (P) of a cutting head of the cutting machine. The method comprises positioning a five-component force transducer on the presser foot, wherein the five-component force transducer comprises a plurality of sensors capable of determining a normal force, a lateral force, a roll torque, a pitch torque, and a yaw torque of the cutting blade; establishing a calibration matrix of the force transducer; determining forces experienced by the cutting blade in three dimensions based on measurements obtained from the sensors and the calibration matrix.

An actuator assembly comprising: a support structure comprising a first friction surface; a movable part comprising a second friction surface engaging the first friction surface; one or more SMA wires arranged. on contraction. to move the movable part relative to the support structure to any position within a range of movement; a biasing arrangement arranged to bias the first and second friction surfaces against each other with a normal force, thereby generating a static frictional force that constrains the movement of the movable part relative to the support structure at any position within the range of movement when the one or more SMA wires are not contracted; wherein the one or more SMA wires are arranged, on contraction, to reduce the normal force between first and second friction surfaces.

The invention belongs to the technical field of wind tunnel tests, and discloses a method for adjusting a loading center of a force application device of a half-mode balance calibration system. The method comprises the steps of establishing a balance calibration center; comparing the size of the balance, and calculating the displacement; adjusting a target position of a normal force application point; and adjusting the target position of the lateral force application point. The method comprises the following steps: taking an initial position state of a reference balance at an initial construction stage of a half-mode balance calibration system as a reference, determining that a loading center of a force application device coincides with a calibration center of the initial balance by using a laser tracker, and recording an original position of each force application point; during subsequent calibration, the size of the balance to be calibrated and the size of the reference balance are subjected to iterative calculation, the target position of each force application point is obtained, and then each force application point is adjusted to the target position by adopting a grating ruler and laser interferometer measurement and worker manual adjustment mode. The balance calibration center of the balance to be calibrated coincides with the loading center of the force application device, and the calibration data accuracy of the balance to be calibrated is ensured.

The invention relates to the use of a handling system (1; 31; 61; 81) for manipulating flexible workpieces (51, 52), which has a drive table (12) with a surface (13) and a slide drive (14) arranged below the surface (13), as well as a first slide (21; 41; 71) which is moved by the slide drive (14) by first drive forces in a first spatial direction (54) and by second drive forces in a second spatial direction (55) which is oriented transversely to the surface (13) and forms a variable-size working gap (18) with the surface (13) which is temporarily larger than the thickness of a first workpiece (51), wherein the first slide (21; 41; 71) is moved over the first workpiece (51) by first drive forces in order to subsequently reduce the working gap (18), so that the first slide (21; 41;71) rests on the first workpiece (51) to exert a normal force on the first workpiece (51) directed towards the surface (13).