A numerical control machine tool arbor end face clamping force measuring mechanism

Abstract

The present application relates to a kind of numerical control machine tool handle end face clamping force measuring mechanism.It includes measuring head and micro-distance adjusting mechanism, micro-distance adjusting mechanism includes screw propulsion mechanism, adapter disk frame and locking mechanism, by piezoelectric ceramic sensor being arranged in the annular groove of the end face of handle end of measuring head, by using screw propulsion mechanism similar to the principle of micrometer, high-precision displacement adjustment is realized, its screw rod front end is matched with the axial stop of the disc of adapter disk frame, circumferential rotation is matched, to drive adapter disk frame axial movement set distance, the horizontal link and vertical link of adapter disk frame successively transmit displacement to piezoelectric ceramic sensor, drive piezoelectric ceramic sensor axial displacement, further change the interference between main shaft and the taper face of handle, realize the high-precision adjustment of online interference, with the advantages of convenient and quick operation, high precision.

Description

Technical Field

[0001] This invention relates to a clamping force measuring mechanism for the end face of a CNC machine tool holder. Background Technology

[0002] The HSK tool holder is a double-sided clamping tool holder developed by the Machine Tool Research Institute of the Technical University of Aachen in Germany in the early 1990s. It is the most representative of double-sided clamping tool holders and has become an important part of machining and manufacturing technology in high-speed cutting.

[0003] In production practice, the safe operation of HSK tool systems places strict requirements on the clamping force of the tool holder, especially the clamping force transmitted to the connection face between the HSK tool holder and the spindle. Since the HSK tool holder requires a certain amount of clamping force to overcome the interference fit with the high-speed spindle while achieving reliable positioning and clamping, directly measuring the clamping force ultimately transmitted to the connection face is of great significance. This necessitates the design of a dedicated measuring device for measuring the end-face clamping force. This device should not only fully ensure the safety and reliability of HSK tool holder positioning and clamping but also reduce the time spent on multiple parameter adjustments in production practice, thereby improving machining efficiency.

[0004] Chinese invention patent CN107131990B discloses an HSK tool holder end face clamping force measuring device, which includes an HSK tool holder measuring head. The rear end of the measuring head is integrally formed to simulate the HSK tool holder structure. An annular groove is provided on the shoulder between the handle and the HSK tool holder. An annular piezoelectric ceramic sensor is provided in the annular groove. The piezoelectric ceramic sensor is electrically connected to a clamping force comb display. The end face of the spindle can directly squeeze the piezoelectric ceramic sensor to detect the pressure on the corresponding end face of the tool holder. To accommodate the measurement of end-face clamping force of HSK tool systems with different interference fits, a precision stainless steel shim with a thickness accuracy of 0.01 mm can be placed between the piezoelectric ceramic sensor and the flat end face of the spindle. This changes the interference fit between the tapered surface of the HSK tool holder and the corresponding tapered surface of the spindle. Since the tapered surface of the HSK tool holder has a 1:10 taper, each additional shim with a thickness of B reduces the interference fit of the corresponding tool holder tapered surface by 0.1B. By adding or removing precision stainless steel shims of different thicknesses, the interference fit between the tapered surface of the tool holder and the tapered surface of the spindle can be adjusted to meet the measurement requirements of the end-face clamping force of HSK tool systems with different interference fits. However, in order to adjust the interference between the tapered surface of the tool holder and the tapered surface of the spindle, when adding or removing the precision stainless steel shims, it is necessary to disengage the jaw wedge clamping mechanism, remove the HSK tool holder from the spindle, and then replace or add or remove the annular precision stainless steel shims. Then, it is necessary to reinstall them for measurement. It can be seen that this method is not only cumbersome, time-consuming and laborious, but also increases the installation error and affects the measurement results. Summary of the Invention

[0005] The purpose of this invention is to provide a clamping force measuring mechanism for the end face of a CNC machine tool holder. When measuring HSK tool systems with different interference amounts, the distance between the end face of the tool holder and the end face of the spindle can be changed directly online, thereby changing the interference amount between the tapered surface of the tool holder and the tapered surface of the spindle. This eliminates the need to disassemble and assemble the measuring head, making it convenient, fast, and highly accurate.

[0006] The technical solution of the present invention is as follows: A clamping force measuring mechanism for the end face of a CNC machine tool tool holder includes: The measuring head has a tool holder end that simulates an HSK tool holder at one end. The tool holder end has an external end face, a conical surface, and an internal conical section for hooking and connecting with the jaw wedge clamping mechanism. The end face has an annular groove, in which an annular piezoelectric ceramic sensor is assembled. The piezoelectric ceramic sensor is electrically connected to a clamping force digital display. The outer end of the piezoelectric ceramic sensor is used to abut against the end face of the spindle. The micro-adjustment mechanism, used to adjust the axial position of the piezoelectric ceramic sensor, includes a screw propulsion mechanism, an adapter plate, and a locking mechanism; The screw propulsion mechanism includes a screw, a nut, a fixed cylinder, and a differential cylinder, which are coaxial with the measuring head and nested together. The nut is fixed relative to the measuring head through the fixed cylinder. The screw has an external thread section that mates with the nut. The thread pitch of both is 0.5 mm. The rear end of the differential cylinder is fixedly connected to the rear end of the screw. The differential cylinder has a scale divided into 50 equal parts. The fixed cylinder has a scale with a minimum scale of 0.5 mm along its axial direction. The adapter plate frame includes a disc coaxially arranged with the screw, multiple horizontal connecting rods are evenly distributed radially on the disc, and vertical connecting rods are perpendicularly connected to the outer ends of the horizontal connecting rods. The vertical connecting rods pass through the preset vertical through hole on the measuring head and are fixedly connected to the piezoelectric ceramic sensor. The front end of the screw is inserted into the disc. The screw and the disc are respectively connected by an annular groove and an annular boss to achieve axial stop fit and circumferential rotation fit. A locking mechanism is used to lock the screw relative to the measuring head so as to transmit the axial force on the screw from the adapter plate to the measuring head.

[0007] Based on the above solution, the following improvements are made: the fixed cylinder is connected to the measuring head through a connecting barrel, the connecting barrel is coaxially arranged with the screw, the disc is located inside the connecting barrel, and the side of the connecting barrel is provided with a corresponding clearance elongated hole corresponding to the cross connecting rod, the length of the clearance elongated hole extends along the axial direction of the screw.

[0008] Based on the above scheme, the following improvements are made: an inner cone is fixedly installed on the screw, and an outer cone with the same taper is coaxially sleeved on the outside of the inner cone. The outer cone can be fixed relative to the connecting barrel by bolts so that the conical surfaces of the inner and outer cones are squeezed together to lock the screw relative to the connecting barrel.

[0009] Based on the above scheme, the following improvements are made: the diameter of the inner cone decreases from the screw towards the measuring head.

[0010] Based on the above scheme, the following improvements are made: the end of the connecting bucket away from the measuring head is provided with multiple first bolt holes evenly distributed on the bottom plate of the bucket, and the outer cone is provided with corresponding second bolt holes. The corresponding bolts are inserted into the first and second bolt holes, and the outer cone is pressed relative to the inner cone by cooperating with the locking nut.

[0011] Based on the above scheme, the following improvement is made: the annular groove and the annular boss are in a transition fit.

[0012] Based on the above solution, the following improvements are made: a reinforcing rib is provided at the corner where the horizontal connecting rod and the vertical connecting rod connect.

[0013] Based on the above scheme, the following improvements are made: the micro-distance adjustment mechanism is made of tool steel and is manufactured using high-precision machining.

[0014] The beneficial effects of this invention: In use, the tool holder end face clamping force measuring mechanism of this invention connects the measuring head to the spindle to be measured, and its jaw wedge clamping mechanism is hooked to the inner conical section of the measuring head. At this time, the end face of the spindle and the end surface of the annular groove of the tool holder are in a pressing fit, and the conical surface of the tool holder and the conical surface of the spindle are also in a pressing fit. The piezoelectric ceramic sensor can detect the clamping force of the end face and display it through a clamping force digital display. When testing different HSK tool systems, because the interference fit of their conical surfaces varies, it is necessary to adaptively adjust the interference fit between the conical surfaces of the tool holder and the spindle. Since the taper of the conical surface is always 1:10, the change in distance between the end faces can be calculated based on the change in the interference fit. Then, only the micro-adjustment mechanism needs to be adjusted according to this change in distance. The principle is similar to that of a micrometer. Since the screw is fixed to the micrometer drum, and the screw is threadedly engaged with the nut fixed relative to the measuring head, with a pitch of 0.5mm, the axial displacement of the screw in one revolution is 0.5mm. Dividing one revolution into 50 parts, the axial displacement of each part is 0.01mm. The screw can be moved a corresponding small distance by turning the micrometer drum. The screw, through the adapter plate, directly drives the annular piezoelectric ceramic sensor to move synchronously in the axial direction, thus realizing the axial movement of the end surface of the piezoelectric ceramic sensor. This allows for adaptive adjustment of the interference fit between the tool holder and the spindle's tapered surface. Subsequently, the screw can be locked relative to the measuring head through a locking mechanism, so that the force on the screw is transmitted to the measuring head, rather than being transmitted to the nut through the thread, which would shorten the thread life. Therefore, the technical solution of this application can directly change the distance between the end face of the tool holder and the end face of the spindle in an online manner when measuring HSK tool systems with different interference amounts, thereby changing the interference amount between the tapered surface of the tool holder and the tapered surface of the spindle. This is convenient, fast and highly accurate, without the need to disassemble the measuring head. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the internal structure of an embodiment of a clamping force measuring mechanism for the end face of a CNC machine tool holder according to the present invention; Figure 2 for Figure 1 A magnified view of a section at point A in the middle; Figure 3 for Figure 1 A magnified view of a section at point B in the middle; Figure 4 for Figure 1 A magnified view of a section at point C; Figure 5 This is a top view of the adapter plate frame; In the diagram: 1-spindle, 11-end face of spindle, 12-conical surface of spindle, 2-clamping jaw wedge clamping mechanism, 3-measuring head, 31-tool holder end, 311-end face of tool holder, 3111-annular groove, 312-conical surface of tool holder, 313-inner conical section, 32-preset vertical through hole, 4-piezoelectric ceramic sensor, 5-clamping force digital display, 6-micro-adjustment mechanism, 61-screw propulsion mechanism, 611-screw 6111-Annular boss, 6112-Inner cone, 612-Nut, 613-Fixing cylinder, 614-Differential cylinder, 615-Connecting cylinder, 6151-Allowing elongated hole, 62-Adapter plate frame, 621-Disc, 6211-Annular groove, 622-Horizontal connecting rod, 623-Vertical connecting rod, 624-Reinforcing rib, 63-Locking mechanism, 631-Outer cone, 632-Bolt, 633-Locking nut. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0018] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0019] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0020] An embodiment of the clamping force measuring mechanism for the end face of a CNC machine tool tool holder according to the present invention: as follows Figure 1 The diagram shown illustrates the internal structure of the CNC machine tool holder end face clamping force measuring mechanism during measurement. It is connected to the spindle 1 and the measuring head 3 is connected and fixed via a jaw wedge clamping mechanism 2 within the spindle 1. The CNC machine tool holder end face clamping force measuring mechanism includes a measuring head 3 and a micro-adjustment mechanism 6.

[0021] like Figure 1 As shown, one end of the measuring head 3 is equipped with a tool holder end 31 simulating an HSK tool holder. The overall structure is a rotating body, made of high-hardness, high-strength tool steel through precision machining with a machining accuracy of 0.01mm. The tool holder end 31 has an external end face (i.e., the end face 311 of the tool holder), a tapered surface 312 of the tool holder (which is an annular plane), an external tapered surface (i.e., the tapered surface 312 of the tool holder) with a taper of 1:10, and an internal tapered section 313 for hooking and connecting with the jaw wedge clamping mechanism 2. An annular groove 3111 is provided on the end face, and an annular piezoelectric ceramic sensor 4 is slidably mounted in the annular groove 3111. The piezoelectric ceramic sensor 4 is electrically connected to the clamping force digital display 5. The outer end of the piezoelectric ceramic sensor 4 is used to abut against the end face 11 of the spindle 1 to detect the clamping force of the end face 11 of the spindle 1 on the end face 311 of the tool holder.

[0022] like Figure 1 As shown, the micro-adjustment mechanism 6 is used to adjust the axial position of the piezoelectric ceramic sensor 4, and includes a spiral propulsion mechanism 61, an adapter plate 62, and a locking mechanism 63.

[0023] like Figure 1 , 2 As shown, the screw propulsion mechanism 61 adopts a technical principle similar to that of the micrometer in the prior art, but its specific structure is different. For example, the structure of its screw 611 and fixed cylinder 613 are different from those in the prior art. Specifically, the screw propulsion mechanism 61 includes a screw 611, a nut 612, a fixed cylinder 613, and a micrometer cylinder 614, which are coaxial with and interlocked with the measuring head 3. The nut 612 is fixed relative to the measuring head 3 through the fixed cylinder 613. The screw 611 has an external thread section that mates with the nut 612, and the thread pitch of both is 0.5 mm. The rear end of the micrometer cylinder 614 is fixedly connected to the rear end of the screw 611. The micrometer cylinder 614 has a scale divided into 50 equal parts, which is set at the front edge of the micrometer cylinder 614 for easy comparison. The fixed cylinder 613 has a scale with a minimum scale of 0.5 mm along its axial direction. The scale is read by comparing the scale on the micrometer cylinder 614 and the fixed cylinder 613, thereby facilitating precise control of the movement distance of the screw 611. The setting and reading methods of the scale on the micrometer cylinder 614 and the fixed cylinder 613 are the same as the corresponding structural principle of the micrometer in the prior art, and will not be described again.

[0024] like Figure 1 , 3 As shown in Figure 4, the adapter plate frame 62 includes a disc 621 coaxially arranged with the screw 611. Multiple horizontal connecting rods 622 are radially evenly distributed on the disc 621 (six in this embodiment). Vertical connecting rods 623 are perpendicularly connected to the outer ends of the horizontal connecting rods 622. The vertical connecting rods 623 pass through a pre-set vertical through-hole 32 on the measuring head 3 and are fixedly connected to the piezoelectric ceramic sensor 4. The front end of the screw 611 is inserted into the disc 621. The screw 611 and the disc 621 are respectively axially stopped and circumferentially rotated through an annular groove 6211 and an annular boss 6111. In this embodiment, the annular groove 6211 is located on the disc 621, and the annular boss 6111 is located on the screw 611. The annular groove 6211 and the annular boss 6111 are a transition fit, ensuring minimal clearance while allowing relative rotation. A reinforcing rib 624 is provided at the corner where the horizontal connecting rod 622 and the vertical connecting rod 623 are connected, so as to improve the strength of the connection and the overall strength, and reduce the amount of deformation between them.

[0025] like Figure 3 As shown, the locking mechanism 63 is used to lock the screw 611 relative to the measuring head 3, so as to transmit the axial force from the adapter plate frame 62 on the screw 611 to the measuring head 3. The fixed cylinder 613 is connected to the measuring head 3 through the connecting barrel 615. The connecting barrel 615 is coaxially arranged with the screw 611. The disc 621 is located inside the connecting barrel 615. The side of the connecting barrel 615 is provided with a corresponding clearance elongated hole 6151 corresponding to the cross link 622. The length of the clearance elongated hole 6151 extends along the axial direction of the screw 611. An inner cone 6112 is fixedly arranged on the screw 611. An outer cone 631 with the same taper is coaxially sleeved on the outer cone 6112. The outer cone 631 can be fixed relative to the connecting barrel 615 by bolts 632, so that the conical surfaces of the inner and outer cones 631 are squeezed together to lock the screw 611 relative to the connecting barrel 615. The diameter of the inner cone 6112 decreases from the screw 611 toward the measuring head 3. The end of the connecting barrel 615 away from the measuring head 3 has multiple first bolt holes evenly distributed on the bottom plate. The outer cone 631 has corresponding second bolt holes. The corresponding bolts 632 are inserted into the first and second bolt holes, and the outer cone 631 is pressed relative to the inner cone 6112 by cooperating with the locking nut 633.

[0026] The micro-adjustment mechanism 6 is made of tool steel and is manufactured using high-precision machining, with an accuracy of 0.01mm.

[0027] In use, the clamping force measuring mechanism of the end 31 face of the CNC machine tool shank of the present invention connects the end 31 face of the measuring head 3 to the spindle 1 to be measured, and hooks the jaw wedge clamping mechanism 2 with the inner tapered section 313 of the measuring head 3. At this time, the end face 11 of the spindle 1 is pressed against the end surface of the annular groove 3111 of the shank, and the tapered surface 312 of the shank is pressed against the tapered surface 12 of the spindle 1. The piezoelectric ceramic sensor 4 can detect the clamping force of the end face and display it through the clamping force digital display instrument 5. When testing different HSK tool systems, the interference of the tapered surface varies, and the interference between the shank and the tapered surface 12 of the spindle 1 needs to be adjusted accordingly. Since the taper of the tapered surface is 1:10, the change in distance between the end faces can be calculated based on the change in the interference of the tapered surface. At this time, it is only necessary to adjust the micro-adjustment mechanism 6 according to the change in distance. The adjustment principle is similar to that of a micrometer. Since the screw 611 is fixedly connected to the micrometer cylinder 614, and the screw 611 is threadedly engaged with the nut 612 fixed relative to the measuring head 3, with a pitch of 0.5mm, the axial displacement of the screw 611 in one rotation is 0.5mm. Dividing the angle of one rotation into 50 parts, the axial displacement corresponding to each part is 0.01mm. The screw 611 can be moved a corresponding small distance by turning the micrometer cylinder 614. The screw 611 then directly drives the annular piezoelectric ceramic sensor 4 to move synchronously in the axial direction via the adapter plate 62, thus realizing the axial movement of the end surface of the piezoelectric ceramic sensor 4. This allows for adaptive adjustment of the interference fit between the tool holder and the tapered surface 12 of the spindle 1. Subsequently, the screw 611 can be locked relative to the measuring head 3 by the locking mechanism 63, so that the force on the screw 611 is transmitted to the measuring head 3, rather than being transmitted to the nut 612 through the thread, which would shorten the thread life. Therefore, the technical solution of this application can change the distance between the tool holder end 31 and the spindle 1 end face directly online when measuring HSK tool systems with different interference amounts, thereby changing the interference amount between the tool holder tapered surface and the spindle 1 tapered surface without disassembling the measuring head 3, which is convenient, fast and highly accurate.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A clamping force measuring mechanism for the end face of a CNC machine tool tool holder, comprising: The measuring head has a tool holder end that simulates an HSK tool holder at one end. The tool holder end has an external end face, a conical surface, and an internal conical section for hooking and connecting with the jaw wedge clamping mechanism. The end face has an annular groove, in which an annular piezoelectric ceramic sensor is assembled. The piezoelectric ceramic sensor is electrically connected to a clamping force digital display. The outer end of the piezoelectric ceramic sensor is used to abut against the end face of the spindle. Its characteristic is that it further includes: The micro-adjustment mechanism, used to adjust the axial position of the piezoelectric ceramic sensor, includes a screw propulsion mechanism, an adapter plate, and a locking mechanism; The screw propulsion mechanism includes a screw, a nut, a fixed cylinder, and a differential cylinder, which are coaxial with the measuring head and nested together. The nut is fixed relative to the measuring head through the fixed cylinder. The screw has an external thread section that mates with the nut. The thread pitch of both is 0.5 mm. The rear end of the differential cylinder is fixedly connected to the rear end of the screw. The differential cylinder has a scale divided into 50 equal parts. The fixed cylinder has a scale with a minimum scale of 0.5 mm along its axial direction. The adapter plate frame includes a disc coaxially arranged with the screw, multiple horizontal connecting rods are evenly distributed radially on the disc, and vertical connecting rods are perpendicularly connected to the outer ends of the horizontal connecting rods. The vertical connecting rods pass through the preset vertical through hole on the measuring head and are fixedly connected to the piezoelectric ceramic sensor. The front end of the screw is inserted into the disc. The screw and the disc are respectively connected by an annular groove and an annular boss to achieve axial stop fit and circumferential rotation fit. A locking mechanism is used to lock the screw relative to the measuring head so as to transmit the axial force on the screw from the adapter plate to the measuring head.

2. The clamping force measuring mechanism for the end face of a CNC machine tool tool holder according to claim 1, characterized in that, The fixed cylinder is connected to the measuring head via a connecting cylinder. The connecting cylinder is coaxially arranged with the screw. The disc is located inside the connecting cylinder. The side of the connecting cylinder is provided with a corresponding clearance elongated hole corresponding to the cross connecting rod. The length of the clearance elongated hole extends along the axial direction of the screw.

3. The clamping force measuring mechanism for the end face of a CNC machine tool holder according to claim 2, characterized in that, An inner cone is fixedly installed on the screw, and an outer cone with the same taper is coaxially sleeved on the outside of the inner cone. The outer cone can be fixed relative to the connecting barrel by bolts so that the conical surfaces of the inner and outer cones are squeezed together to lock the screw relative to the connecting barrel.

4. The clamping force measuring mechanism for the end face of a CNC machine tool tool holder according to claim 3, characterized in that, The diameter of the inner cone decreases from the screw towards the measuring head.

5. The clamping force measuring mechanism for the end face of a CNC machine tool holder according to claim 4, characterized in that, The end of the connecting bucket away from the measuring head is provided with multiple first bolt holes evenly distributed on the bottom plate of the bucket, and the outer cone is provided with corresponding second bolt holes. The corresponding bolts are inserted into the first and second bolt holes, and the outer cone is pressed relative to the inner cone by cooperating with the locking nut.

6. The clamping force measuring mechanism for the end face of a CNC machine tool tool holder according to claim 1, characterized in that, The annular groove and the annular boss are in a transition fit.

7. The clamping force measuring mechanism for the end face of a CNC machine tool tool holder according to claim 1, characterized in that, The corner where the horizontal connecting rod and the vertical connecting rod connect is provided with a reinforcing rib.

8. The clamping force measuring mechanism for the end face of a CNC machine tool holder according to claim 1, characterized in that, The micro-adjustment mechanism is made of tool steel and is manufactured using high-precision machining.

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