# US 8,783,998 B2 · Force-fitting clamping connection and method for its production > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,783,998 B2 - Document ID: US8783998B2 - Status: Granted - Kind: B2 - Application number: 12/060,205 - Filed: 2008-03-31 - Published: 2008-10-09 - Granted: 2014-07-22 - Earliest claimed: 2007-04-05 - Assignees: Ellergon Antriebstechnik Gesellschaft m.b.H. - Applicants: Matthias Geislinger; Cornelius Geislinger; Christof Sigle - Inventors: Matthias Geislinger; Cornelius Geislinger; Christof Sigle - Web page: https://patentgrep.com/patent/US8783998B2 ## CPC - F16B 2/005: {Means to increase the friction-coefficient} - F16B 5/02: by means of fastening members using screw-thread ({F16B5/0004 takes precedence}; construction of screw-threaded connections F16B25/00 - F16B39/00) - F16B 37/00: Nuts or like thread-engaging members {(specially shaped for rotations by a tool F16B23/00)} - F16B 39/282: Locking by means of special shape of work-engaging surfaces, e.g. notched or toothed nuts - F16B 2200/506: bolted or riveted - Y10T 29/49966: with supplemental joining - Y10T 403/7123: Traversed by connector - Y10T 403/75: having a joining piece extending through aligned openings in plural members - Y10T 403/76: having a cam, wedge, or tapered portion - F16B: DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING (couplings for transmitting rotation F16D) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A force-fitting clamping connection includes a first metal clamping surface, a second metal clamping surface, and a clamping element for clamping the clamping surfaces against one another. The first clamping surface forms a hardened fine surface structure with microreliefs and microdepressions. The second clamping surface has a lower hardness than the first clamping surface. Preferably, the first clamping surface is surface-treated by sand-blasting, shot-blasting or embossing before the hardening operation. This allows permanently high friction coefficient values between the clamping surfaces. A flange connection includes such a clamping connection for transmitting high torques. ## Claims ### Claim 1 A force-fitting clamping connection comprising: a first metal clamping surface; a second metal clamping surface; and a clamping element for clamping the clamping surfaces against one another; wherein the first clamping surface forms a metal surface structure with microreliefs and microdepressions, said metal surface structure being surface-treated and hardened; wherein the second clamping surface has a lower hardness than the first clamping surface; wherein the second metal clamping surface has a lower surface roughness than the first metal clamping surface; wherein the first metal clamping surface has an average roughness depth RZ in the range from 10 to 100 μm; and wherein the second metal clamping surface has an average roughness depth RZ in the range from 2.5 to 40 μm. ### Claim 2 (depends on 1) A force-fitting clamping connection according to claim 1, wherein the microreliefs and microdepressions are obtained by a surface treatment which increases the roughness. ### Claim 3 (depends on 2) A force-fitting clamping connection according to claim 2, wherein the metal surface structure of the first metal clamping surface having said microreliefs and microdepressions is a sand-blasted, shot-blasted, or embossed surface structure. ### Claim 4 (depends on 1) A force-fitting clamping connection according to claim 1, wherein a friction surface pair consisting of the first and second clamping surface has a friction value in the range from 0.20 to 0.5. ### Claim 5 (depends on 1) A force-fitting clamping connection according to claim 1, wherein the first clamping surface has sections comprising microreliefs and microdepressions with a first surface roughness and also further sections with a lower surface roughness and wherein the first surface roughness is greater than the second surface roughness. ### Claim 6 (depends on 1) A force-fitting clamping connection according to claim 1, wherein the first clamping surface has surface-treated sections and non-surface-treated sections, wherein the surface-treated sections have a greater surface roughness than the non-surface-treated sections. ### Claim 7 (depends on 1) A force-fitting clamping connection according to claim 1, wherein the first clamping surface is completely surface-treated. ### Claim 8 (depends on 1) A force-fitting clamping connection according to claim 1, wherein the clamping connection is releasable. ### Claim 9 A flange connection comprising: a first flange; a second flange; one or more clamping sleeves and also clamping elements assigned to the one or more clamping sleeves respectively for fixing the second flange to the first flange; wherein each clamping sleeves is clamped with end sides against the first flange in a force-fitting manner and are in engagement with the second flange via a bearing pressure, and; wherein a first clamping surface is formed on the end side of each of said one or more clamping sleeves, a second metal clamping surface is formed on the first flange and each first metal clamping surface at each of said clamping sleeves engages with the second metal clamping surface at the first flange, respectively; wherein said one or more clamping elements clamp said first metal clamping surfaces at each of said one or more clamping sleeve against said second metal clamping surfaces at the first flange, respectively; wherein the first metal clamping surface forms a metal surface structure with microreliefs and microdepressions, said metal surface structure being surface-treated and hardened; wherein the second metal clamping surface has a lower hardness than the first metal clamping surface; wherein the first metal clamping surface has an average roughness depth RZ in the range from 10 to 100 μm; and wherein the second metal clamping surface has an average roughness depth RZ in the range from 2.5 to 40 μm. ### Claim 10 (depends on 9) A flange connection according to claim 9, wherein the second flange is adhesively bonded to the clamping sleeves. ### Claim 11 (depends on 9) A flange connection according to claim 9, wherein said one or more clamping sleeves in each case have a tapered extension which extends into a corresponding hole opening of the second flange, wherein the axial length of the extension is equal to or slightly greater than the hole depth of the hole opening, and any axial compensation with respect to the first flange takes place by means of adhesive material.