Mechanism for measuring clamping force of end face of cutter handle of numerical control machine tool

Abstract

The invention relates to a numerical control machine tool shank end face clamping force measuring mechanism. Comprising a measuring head and a micro-distance adjusting mechanism, the micro-distance adjusting mechanism comprises a spiral propelling mechanism, a switching disc frame and a locking mechanism, a piezoelectric ceramic sensor is arranged in an annular groove in the end face of the cutter handle end of the measuring head, and high-precision displacement adjustment is achieved by adopting the spiral propelling mechanism similar to the micrometer principle. The front end of a screw rod is in axial stop fit and circumferential rotation fit with a disc of a switching disc frame so as to drive the switching disc frame to axially move by a set distance, a transverse connecting rod and a vertical connecting rod of the switching disc frame sequentially transmit displacement to a piezoelectric ceramic sensor, the piezoelectric ceramic sensor is driven to axially move, and then the magnitude of interference between a main shaft and the conical surface of a cutter handle is changed. The online interference magnitude adjusting device has the advantages of being convenient and fast to operate and high in precision.

Description

Technical Field

[0001] The invention relates to a mechanism for measuring the clamping force of a tool handle end face of a numerically controlled machine tool. Background Art

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

[0003] In production practice, the safe operation of HSK tool systems places strict demands on toolholder clamping force, particularly the clamping force transmitted to the end face connecting the HSK toolholder to the spindle. Because the HSK toolholder consumes some clamping force to achieve reliable positioning and clamping while overcoming the interference fit with the high-speed spindle, it is crucial to directly measure the clamping force ultimately transmitted by the clamping mechanism to the end face. This requires the design of a dedicated device for measuring end face clamping force. This not only fully ensures the safety and reliability of HSK toolholder positioning and clamping, but also reduces the time required for multiple parameter adjustments during production, thereby improving processing efficiency.

[0004] A Chinese invention patent with authorization publication number CN107131990B discloses a device for measuring the clamping force of an HSK toolholder end face. The device includes an HSK toolholder measuring head. The rear end of the measuring head is integrally formed to simulate the HSK toolholder structure. An annular groove is provided on the shoulder between the handle and the HSK toolholder. 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 toolholder. In order to adapt to the end face clamping force measurement of HSK tool systems with different interference amounts, a precision stainless steel gasket with a thickness accuracy of 0.01mm can be set between the piezoelectric ceramic sensor and the flat end face of the spindle to change the interference between the conical surface of the HSK tool holder and the corresponding conical surface of the spindle. Since the conical surface of the HSK tool holder has a taper of 1:10, for every additional gasket with a thickness value of B, the interference of the corresponding tool holder conical surface is reduced by 0.1B. By adding or removing precision stainless steel gaskets of different thicknesses, the interference between the tool holder conical surface and the spindle conical surface can be adjusted to meet the measurement of the end face clamping force of HSK tool systems with different interference amounts. However, in order to adjust the interference between the cone surface of the tool holder and the cone surface of the spindle, when adding or removing the precision stainless steel gasket, it is necessary to disengage the clamping jaw wedge clamping mechanism, remove the HSK tool holder from the spindle, and then replace or add or remove the annular precision stainless steel gasket. Then it needs to be reinstalled for measurement. It can be seen that this method is not only cumbersome and time-consuming, but also reinstallation will increase the installation error and affect the measurement results. Summary of the Invention

[0005] The purpose of the present invention is to provide a mechanism for measuring the clamping force of a tool holder end face of a CNC machine tool. When measuring HSK tool systems with different interference fits, the distance between the tool holder end face and the spindle end face can be directly changed online, thereby changing the interference fit between the tool holder tapered surface and the spindle tapered surface. This method does not require disassembly of the measuring head, and is convenient, fast, and highly accurate.

[0006] The technical solution of the present invention is as follows: A CNC machine tool handle end face clamping force measuring mechanism comprises: A measuring head, one end of which is provided with a tool holder end simulating an HSK tool holder, the tool holder end having an external end face, a conical surface, and an internal conical section for hooking and connecting with the clamping claw wedge clamping mechanism; an annular groove is provided on the end face, and an annular piezoelectric ceramic sensor is mounted in the annular groove. The piezoelectric ceramic sensor is electrically connected to the clamping force digital display, and the outer end of the piezoelectric ceramic sensor is used to abut against the end face of the spindle; A macro adjustment mechanism, used to adjust the axial position of the piezoelectric ceramic sensor, including a screw propulsion mechanism, an adapter plate frame and a locking mechanism; The screw propulsion mechanism includes a screw, a nut, a fixed cylinder, and a differential cylinder that are coaxial with the measuring head and sleeved together. The nut is fixed relative to the measuring head by the fixed cylinder. The screw is provided with an external threaded section that cooperates with the nut. The pitch of the threads 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 is provided with a scale divided into 50 parts. The fixed cylinder is provided with a scale with a minimum scale of 0.5 mm along its axial direction. The adapter disc frame includes a disc coaxially arranged with the screw, with multiple horizontal connecting rods evenly distributed radially on the disc, and vertical connecting rods perpendicularly connected to the outer ends of the horizontal connecting rods. The vertical connecting rods pass through preset vertical through holes on the measuring head and are fixedly connected to the piezoelectric ceramic sensor. The front end of the screw is installed in the disc, and 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; The locking mechanism is used to lock the screw relative to the measuring head so as to transmit the axial force exerted on the screw from the adapter plate to the measuring head.

[0007] On the basis of the above scheme, further improvements are made as follows: 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 in the connecting barrel, and the side of the connecting barrel is provided with a corresponding avoidance long hole corresponding to the horizontal connecting rod, and the length of the avoidance long hole extends along the axial direction of the screw.

[0008] On the basis of the above scheme, further improvements are made as follows: an inner cone is fixedly provided on the screw, and an outer cone with the same taper is provided on the outer coaxial sleeve 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 to lock the screw relative to the connecting barrel.

[0009] On the basis of the above solution, a further improvement is made as follows: the diameter of the inner cone decreases from the screw toward the measuring head.

[0010] On the basis of the above scheme, further improvements are made as follows: a plurality of first bolt holes are evenly distributed on the bottom plate of the barrel at the end of the connecting barrel away from the measuring head, and second bolt holes are provided on the outer frustum in one-to-one correspondence. The outer frustum is pressed relative to the inner frustum by means of corresponding bolts inserted into the first and second bolt holes, and the outer frustum is pressed relative to the inner frustum by means of cooperation with the locking nut.

[0011] Based on the above solution, a further improvement is made as follows: the annular groove and the annular boss are transition fit.

[0012] Based on the above solution, a further improvement is made as follows: reinforcing ribs are provided at the corners where the horizontal connecting rods and the vertical connecting rods are connected.

[0013] On the basis of the above scheme, further improvements are made as follows: the material of the macro adjustment mechanism is tool steel and is made by high-precision processing.

[0014] Beneficial effects of the present invention: When the tool holder end face clamping force measuring mechanism of the present invention is in use, the tool holder end of the measuring head is connected to the spindle to be measured, and the clamping claw wedge clamping mechanism is hooked and connected with the inner cone section of the measuring head. At this time, the end face of the spindle is squeezed and matched with the end surface of the annular groove of the tool holder, and the conical surface of the tool holder is squeezed and matched with the conical surface of the spindle. The piezoelectric ceramic sensor can detect the clamping force of the end face and display it through the clamping force digital display. When detecting different HSK tool systems, due to the change in the interference of the conical surface, it is necessary to adaptively adjust the interference between the tool holder and the conical surface of the spindle. Since the taper of the conical surface is 1:10, the distance change between the end faces can be inferred based on the change in the interference of the conical surface. At this time, it is only necessary to adjust the macro adjustment mechanism based on the distance change. The principle is similar to that of a micrometer. Since the screw is fixedly connected to the differential cylinder, the screw cooperates with the nut thread fixed relative to the measuring head, and the pitch is 0.5mm, that is, the axial displacement of the screw after one rotation is 0.5mm. The angle of one rotation is divided into 50 parts. For each rotation, the corresponding axial displacement is 0.01mm. The screw can be moved a corresponding small distance by screwing the differential cylinder, and the screw directly drives the annular piezoelectric ceramic sensor to move a corresponding distance in the axial direction through the adapter plate, that is, the axial movement of the end surface of the piezoelectric ceramic sensor is realized, so that the interference between the conical surface of the tool holder and the spindle can be adaptively adjusted. Then the screw can be locked relative to the measuring head through the locking mechanism, so that the force on the screw is transmitted to the measuring head, rather than to the nut through the thread, which shortens the thread life. It can be seen that the technical solution of the present 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 fits, thereby changing the interference fit between the conical surface of the tool holder and the conical surface of the spindle, without the need to disassemble the measuring head. It is convenient, fast and highly accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the internal structure of an embodiment of a mechanism for measuring the end face clamping force of a tool holder for a CNC machine tool according to the present invention; Figure 2 for Figure 1 A partial enlarged view of point A in the middle; Figure 3 for Figure 1 A partial enlarged view of point B in the middle; Figure 4 for Figure 1 A partial enlarged view of point C in the middle; Figure 5 A top view of the transfer tray rack; In the figure: 1-spindle, 11-end face of spindle, 12-conical surface of spindle, 2-clamping jaw wedge clamping mechanism, 3-measuring head, 31-shank end, 311-end face of tool holder, 3111-annular groove, 312-conical surface of tool holder, 313-inner cone section, 32-preset vertical through hole, 4-piezoelectric ceramic sensor, 5-clamping force digital display, 6-macro adjustment mechanism, 61-screw propulsion mechanism, 611-screw , 6111-annular boss, 6112-inner cone, 612-nut, 613-fixed cylinder, 614-differential cylinder, 615-connecting barrel, 6151-avoidance long hole, 62-adapter disc frame, 621-disc, 6211-annular groove, 622-horizontal connecting rod, 623-vertical connecting rod, 624-reinforcement rib, 63-locking mechanism, 631-outer cone, 632-bolt, 633-locking nut. DETAILED DESCRIPTION

[0016] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is 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 intended to explain the present invention and are not intended to limit the present invention. That is, the embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in various different configurations.

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

[0018] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

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

[0020] An embodiment of a CNC machine tool handle end face clamping force measuring mechanism of the present invention: Figure 1 Figure 2 shows the internal structure of the clamping force measurement mechanism for toolholders of a CNC machine tool during measurement. The mechanism is connected to a spindle 1 and secured to a measuring head 3 via a jaw-wedge clamping mechanism 2 within the spindle 1. The clamping force measurement mechanism for toolholders of a CNC machine tool 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 shank end 31 that simulates an HSK tool shank. The entire structure is a solid of revolution and is precision-machined from high-hardness, high-strength tool steel to a machining accuracy of 0.01 mm. The shank end 31 has an external end face (i.e., the shank end face 311), a tapered surface 312 of the shank that is an annular flat surface with a taper of 1:10, and an internal tapered section 313 for hooking with the jaw wedge clamping mechanism 2. An annular groove 3111 is provided on the end face, into which an annular piezoelectric ceramic sensor 4 is slidably mounted. 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 designed to abut against the end face 11 of the spindle 1 to detect the clamping force exerted by the spindle 1 on the shank end face 311.

[0022] like Figure 1 As shown, the macro adjustment mechanism 6 is used to adjust the axial position of the piezoelectric ceramic sensor 4 , and includes a screw propulsion mechanism 61 , an adapter disc frame 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, its screw 611, fixed cylinder 613 and other structures are different from those in the prior art. Specifically, the screw advancement mechanism 61 includes a screw 611, a nut 612, a fixed cylinder 613 and a differential cylinder 614 that are coaxial with the measuring head 3 and sleeved with each other. The nut 612 is fixed relative to the measuring head 3 by the fixed cylinder 613. The screw 611 is provided with an external thread section that cooperates with the nut 612. The pitch of the threads of both is 0.5 mm. The rear end of the differential cylinder 614 is fixedly connected to the rear end of the screw 611. The differential cylinder 614 is provided with a scale divided into 50 parts. The scale is set at the front edge of the differential cylinder 614 to facilitate comparison. The fixed cylinder 613 is provided with a scale with a minimum scale of 0.5 mm along its axial direction. The scale reading is achieved by comparing the scales on the differential cylinder 614 and the fixed cylinder 613, thereby facilitating the precise control of the moving distance of the screw 611. The setting method and reading method of the scales on the differential cylinder 614 and the fixed cylinder 613 are the same as the corresponding structural principles of the micrometer in the prior art and will not be repeated here.

[0024] like Figure 1 、 3 As shown in Figures 4 and 5, the adapter disc frame 62 includes a disc 621 coaxially arranged with the screw 611. The disc 621 is evenly distributed with a plurality of horizontal connecting rods 622 in the radial direction. In this embodiment, six horizontal connecting rods 622 are provided. Vertical connecting rods 623 are perpendicularly connected to the outer ends of the horizontal connecting rods 622. The vertical connecting rods 623 pass through the preset vertical through-holes 32 on the measuring head 3 and are fixedly connected to the piezoelectric ceramic sensor 4. The front end of the screw 611 is installed in the disc 621. The screw 611 and the disc 621 are respectively connected by an annular groove 6211 and an annular boss 6111 to achieve axial stop fit and circumferential rotation fit. In this embodiment, the annular groove 6211 is provided on the disc 621, and the annular boss 6111 is provided on the screw 611. The annular groove 6211 and the annular boss 6111 are transition fits, and have a minimum fit clearance while ensuring 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 to improve the strength of the connection and the overall strength and reduce the deformation of each other.

[0025] like Figure 3 As shown, the locking mechanism 63 is used to lock the screw 611 relative to the measuring head 3, thereby transmitting the axial force exerted on the screw 611 by the adapter plate frame 62 to the measuring head 3. The fixed cylinder 613 is connected to the measuring head 3 via the connecting barrel 615. The connecting barrel 615 is coaxially arranged with the screw 611. The disc 621 is located within the connecting barrel 615. The side of the connecting barrel 615 is provided with a corresponding escape slot 6151 corresponding to the cross-link 622. The escape slot 6151 extends axially along the screw 611. An inner cone 6112 is fixedly mounted on the screw 611. An outer cone 631 of the same tapered shape is coaxially mounted outside the inner cone 6112. The outer cone 631 is fixed to the connecting barrel 615 via a bolt 632, so that the tapered surfaces of the inner and outer cones 631 are compressed, locking the screw 611 relative to the connecting barrel 615. The diameter of the inner cone 6112 decreases gradually from the screw 611 toward the measuring head 3. The end of the connecting barrel 615, away from the measuring head 3, is provided with a plurality of evenly spaced first bolt holes on the barrel bottom plate. The outer cone 631 is provided with corresponding second bolt holes. Bolts 632 are inserted through the corresponding first and second bolt holes and, in conjunction with locking nuts 633, tighten the outer cone 631 against the inner cone 6112.

[0026] The material of the macro adjustment mechanism 6 is tool steel and is processed with high precision to an accuracy of 0.01 mm.

[0027] When using a clamping force measuring mechanism for the tool holder end 31 of a CNC machine tool of the present invention, the tool holder end 31 of the measuring head 3 is connected to the spindle 1 to be measured, and the clamping claw wedge clamping mechanism 2 is hooked and connected with the inner cone section 313 of the measuring head 3. At this time, the end face 11 of the spindle 1 is squeezed and fitted with the end surface of the annular groove 3111 of the tool holder, and the conical surface 312 of the tool holder is squeezed and fitted with the conical 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 5. When detecting different HSK tool systems, due to the change in the interference of the conical surface, it is necessary to adaptively adjust the interference between the tool holder and the conical surface 12 of the spindle 1. Since the taper of the conical surface is 1:10, the distance change between the end faces can be inferred according to the change in the interference of the conical surface. At this time, it is only necessary to adjust the macro adjustment mechanism 6 according to the distance change. The adjustment principle is similar to that of the micrometer. Since the screw 611 is fixedly connected to the differential cylinder 614, the screw 611 is threadedly matched with the nut 612 fixed relative to the measuring head 3, and the pitch is 0.5mm, that is, the axial displacement of the screw 611 after one rotation is 0.5mm. The angle of one rotation is divided into 50 parts, and the corresponding axial displacement for each rotation is 0.01mm. The screw 611 can be moved by a corresponding small distance by screwing the differential cylinder 614, and the screw 611 directly drives the annular piezoelectric ceramic sensor 4 to move a corresponding distance in the axial direction through the adapter plate 62, that is, the axial movement of the end surface of the piezoelectric ceramic sensor 4 is realized, so that the interference between the tool handle and the tapered surface 12 of the spindle 1 can be adaptively adjusted. Then, 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 shortens the thread life. It can be seen that the technical solution of the present application can directly change the distance between the end face of the tool holder 31 and the end face of the spindle 1 in an online manner when measuring HSK tool systems with different interference fits, thereby changing the interference fit between the conical surface of the tool holder and the conical surface of the spindle 1, without the need to disassemble the measuring head 3, which is convenient, fast and highly accurate.

[0028] The above description is only 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 based on the claims. Any equivalent structural changes made using the description and drawings of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A mechanism for measuring the end face clamping force of a tool holder of a CNC machine tool, comprising: A measuring head, one end of which is provided with a tool holder end simulating an HSK tool holder, the tool holder end having an external end face, a conical surface, and an internal conical section for hooking and connecting with the clamping claw wedge clamping mechanism; an annular groove is provided on the end face, and an annular piezoelectric ceramic sensor is mounted in the annular groove. The piezoelectric ceramic sensor is electrically connected to the clamping force digital display, and the outer end of the piezoelectric ceramic sensor is used to abut against the end face of the spindle; It is characterized by further comprising: A macro adjustment mechanism, used to adjust the axial position of the piezoelectric ceramic sensor, including a screw propulsion mechanism, an adapter plate frame and a locking mechanism; The screw propulsion mechanism includes a screw, a nut, a fixed cylinder, and a differential cylinder that are coaxial with the measuring head and sleeved together. The nut is fixed relative to the measuring head by the fixed cylinder. The screw is provided with an external threaded section that cooperates with the nut. The pitch of the threads 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 is provided with a scale divided into 50 parts. The fixed cylinder is provided with a scale with a minimum scale of 0.5 mm along its axial direction. The adapter disc frame includes a disc coaxially arranged with the screw, with multiple horizontal connecting rods evenly distributed radially on the disc, and vertical connecting rods perpendicularly connected to the outer ends of the horizontal connecting rods. The vertical connecting rods pass through preset vertical through holes on the measuring head and are fixedly connected to the piezoelectric ceramic sensor. The front end of the screw is installed in the disc, and 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; The locking mechanism is used to lock the screw relative to the measuring head so as to transmit the axial force exerted on the screw from the adapter plate to the measuring head.

2. A CNC machine tool shank end face clamping force measuring mechanism according to claim 1, characterized in that: 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 in the connecting barrel, and the side of the connecting barrel is provided with a corresponding avoidance long hole corresponding to the horizontal connecting rod, and the length of the avoidance long hole extends along the axial direction of the screw.

3. A CNC machine tool shank end face clamping force measuring mechanism according to claim 2, characterized in that: An inner cone is fixed on the screw, and an outer cone with the same taper is provided on the outer coaxial sleeve 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 tightly to lock the screw relative to the connecting barrel.

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

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

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

7. The CNC machine tool tool handle end face clamping force measuring mechanism according to claim 1, characterized in that: Reinforcement ribs are provided at the corners where the horizontal connecting rods and the vertical connecting rods are connected.

8. The CNC machine tool tool handle end face clamping force measuring mechanism according to claim 1, characterized in that: The macro adjustment mechanism is made of tool steel and is machined with high precision.

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