CN204101468U - Electronic product surface quality detection device - Google Patents

Abstract

The utility model discloses a surface quality detection device for electronic products, which is characterized in that it comprises a box body, the box body is provided with a cavity; a light source, the light source is used to emit monochromatic light to the product to be tested, the The light source is arranged in the cavity; the camera, the camera is used to take pictures of the product to be detected under the light source; the delivery device; the delivery device is used to transport the product to be detected into the cavity, and After the detection is completed, it is output from the cavity; the delivery device transports the product to be detected to the cavity of the box, and the light source emits monochromatic light to the product to be detected; Take pictures of the product to be tested under the light source. The utility model uses the transmission device to transport the product to be detected to the detection position, and outputs after detection, which is convenient for operation. The light source can be set movably, so that it can be applied to products of various sizes, and there are many applicable occasions.

Description

Electronic product surface quality testing device

technical field

The utility model relates to a detection device, in particular to a detection device for the surface quality of electronic products.

Background technique

Some structures in electronics are made of plastic, such as the housings of connectors. The structure of the connector is various. The socket connector used on the tablet computer is used for the electrical connection between the power supply and the liquid crystal display module; it is arranged on the back of the liquid crystal display module. The receptacle consists of a plastic housing and a reversible cover. After the plug is plugged into the socket, the cover can be used to lock the plug to prevent loosening or falling off. Since the assembly of the liquid crystal display involves multiple processes, there is a risk of being damaged in each process. For example, scratches, pits, or even fractures and peelings are formed on the surface of the cover. Whether it is based on aesthetic requirements or functional requirements, defects such as scratches, dents, breaks, and shedding will affect the continued use of the product. Labels, protective films, etc. may be attached to some products. In the various production processes, there is also a risk of damage. For example, the label falls off, some parts are missing, etc. Therefore, during the production process of the product, it is necessary to test the product. In the prior art, inspectors use the naked eye, or use a magnifying glass to assist observation and inspection to judge whether there is a defect in the product. This detection method is inefficient, labor-intensive, and requires high personnel, which is easy to cause visual fatigue, and even long-term detection will affect the eyesight of workers.

Utility model content

The purpose of the utility model is to overcome the deficiencies in the prior art and provide a surface quality detection device for electronic products that can conveniently detect the surface quality of products.

In order to achieve the above purpose, the utility model is realized through the following technical solutions:

The electronic product surface quality detection device is characterized in that, comprising,

A box body, the box body is provided with a cavity;

A light source, the light source is used to emit monochromatic light to the product to be detected, and the light source is arranged in the cavity;

A camera, which is used to take pictures of the product to be detected under the light source;

A conveying device; the conveying device is used to convey the product to be tested into the cavity, and output it from the cavity after the detection is completed;

The conveying device conveys the product to be inspected into the cavity of the box body, and the light source emits monochromatic light to the product to be inspected; the camera takes pictures of the product to be inspected under the illumination of the light source.

Preferably, the conveying device includes a drive motor and a drive shaft; the number of the drive shafts is multiple, forming a conveying route of the product to be inspected; the drive motor drives the multiple drive shafts to rotate synchronously.

Preferably, a conveying roller is sleeved on the driving shaft; the conveying roller protrudes from the driving shaft; and the conveying roller rotates with the driving shaft.

Preferably, the drive motor drives the plurality of drive shafts to rotate synchronously through a transmission belt; a pulley is provided on the drive shaft; and the transmission belt cooperates with the pulley.

Preferably, a first stopper is also provided in the cavity; the first stopper is set on the travel route of the product to be detected and can be moved up and down; after the first stopper rises, Protrude from the product to be detected and block the product to be detected from advancing.

Preferably, an inductor is also arranged in the cavity, and the sensor is arranged on the travel route of the product to be detected; when the product to be detected is transported to a designated position, the sensor generates an electrical signal and The electric signal is transmitted; when the sensor detects that the product to be detected moves to a designated position, the first stopper rises and protrudes beyond the product to be detected, preventing the product to be detected from advancing.

Preferably, a first air cylinder is also included, and the first air cylinder drives the first block to go up and down.

Preferably, a push block is also provided in the cavity, the push block is movably arranged on one side of the travel route of the product to be detected, and the push block is used to push the product to be detected to move horizontally .

Preferably, a second stopper is further provided in the cavity, and the second stopper and the pushing block are respectively arranged on both sides of the travel route of the product to be detected.

Preferably, a second air cylinder is also included; the second block is arranged to be movable horizontally; the second air cylinder drives the second block to move horizontally.

Preferably, the number of the second stoppers is more than two and arranged at intervals; the second stoppers are installed on the second positioning bracket; the second positioning bracket is connected with the piston rod of the second cylinder.

Preferably, the push block is arranged to be movable horizontally, and when the push block moves horizontally, the product to be detected is pushed to move.

Preferably, a first scale is also included, and the first scale is arranged parallel to the push block.

Preferably, a third air cylinder is also included, and the third air cylinder drives the push block to move horizontally.

Preferably, it also includes a first transmission device; the push block is arranged on the first positioning bracket; the driving force drives the first positioning bracket to move through the first transmission device; when the first positioning bracket moves, it drives The push block moves.

Preferably, the first transmission device includes a first screw, and the first screw drives the first positioning bracket to move through rotation.

Preferably, a first guide device is also included, the first guide device includes a first slider and a first guide rail; the first slider is slidably mounted on the first guide rail along the first guide rail ; The first positioning bracket is mounted on or mounted on one of the first slider and the first guide rail through a positioning plate.

Preferably, the light source is a monochromatic light source, and the light source is arranged above the moving route of the product to be detected.

Preferably, the light source is a blue light source.

Preferably, the monochromatic light source is installed in the cavity in a liftable manner.

Preferably, the camera is arranged above the product to be inspected in a manner that can be lifted up and down and moved horizontally.

Preferably, one or both of the second scale and the third scale are further included, and the second scale and the third scale are respectively arranged parallel to the lifting direction and the horizontal moving direction of the camera.

Preferably, it also includes a vertical position adjustment device and a horizontal position adjustment device, the vertical position adjustment device is used to adjust the vertical position of the camera; the horizontal position adjustment device is used to adjust the horizontal position of the camera.

Preferably, a second guiding device is further included, and the second guiding device is used to limit the moving track of the camera when the camera is moved up and down or horizontally.

Preferably, the camera is installed on the up and down moving block; the lower moving block is arranged above the up and down moving block; the upper end plate is installed on the lower moving block through the first guide shaft; the up and down moving block can be moved along the first guide The shaft is movably sleeved on the first guide shaft; the fourth screw rod is rotatably mounted on the upper end plate, passes through the lower moving block, and is threadedly engaged with the up and down moving block; the lower moving block can Move along the second guide shaft and fit on the second guide shaft; the end of the second guide shaft is installed on the shaft seat; a rotatable second screw rod is installed on the shaft seat, and the second screw rod and the lower moving block thread fit; the shaft seat is installed on the second slider, and the second slider can be slidably installed on the second guide rail along the second guide rail; the second guide rail is installed on the base; There is a rotatable third screw rod, and the third screw rod is threadedly engaged with the second slider.

The inventor of the utility model has found through research that for products with a certain structure, when the light source is irradiated, their reflections on light are the same. When there are differences in product structure, there are differences in the reflection of light. For example, when the surface of a product has scratches, dents, protrusions, or parts are missing, there is a difference in the reflection of light compared to a product without these conditions. Comparing the light reflection of the product with normal quality and the product to be tested can judge whether the quality of the product to be tested is normal. The electronic product surface quality detection device in the utility model uses a monochromatic light source to irradiate the product to be tested, uses a camera to take pictures, and judges whether the surface quality of the electronic product is good or bad according to the photographed results. In the utility model, a monochromatic light source is firstly used to irradiate products with normal quality, and a camera is used to take pictures, and the photographed images are used as standard images. Then use a monochromatic light source to irradiate the product to be inspected, use a camera to take pictures, and compare the brightness of the image formed by the photo with the standard image brightness. If the brightness of the photographed image is the same as the standard image brightness or does not exceed the specified standard, then judge the product to be inspected The quality is normal. When the brightness of a certain area differs greatly from the standard image, it can be judged that there is a quality problem there. For the products to be inspected that are preliminarily judged to have quality problems, they can be photographed again for inspection and confirmation, or the staff can focus on inspections to finally judge whether the quality is normal.

The utility model can be used for detecting the quality state of the surface of electronic products, and is especially suitable for detecting the quality state of the back of the liquid crystal display module of the tablet computer. Regardless of whether the back of the tablet LCD module is flat or has connectors, labels or protective films on the back, it can detect scratches, dents or protrusions, partial or complete absence of labels and protective films on the back .

The utility model uses the transmission device to transport the product to be detected to the detection position, and outputs after detection, which is convenient for operation. The light source can be set movably, so that it can be applied to products of various sizes, and there are many applicable occasions. The utility model can also accurately observe the moving distance of the camera, and control its position conveniently and accurately. The utility model can also accurately observe the moving distance of the push block, and conveniently and accurately control the position of the product to be detected.

Description of drawings

Fig. 1 is a schematic diagram of the external structure of the utility model.

Fig. 2 is a schematic diagram of the external structure of the utility model viewed from another angle, and the top plate of the box is not shown in Fig. 2 .

Fig. 3 is a front view of the internal structure of the utility model.

Fig. 4 is a structural schematic diagram of the conveying device of the present invention.

Fig. 5 is a side view of the conveying device in the utility model.

Fig. 6 is a schematic structural diagram of the positioning device in the present invention.

Fig. 7 is a schematic structural diagram of the irradiation device in the present invention.

Fig. 8 is a schematic structural diagram of the photographing device in the present invention.

FIG. 9 is a structural schematic view of the photographing device in the present invention viewed from another angle.

Detailed ways

Below in conjunction with embodiment and accompanying drawing, the utility model is further described.

As shown in FIG. 1 and FIG. 2 , the electronic product surface quality detection device includes a box 100 . The box body 100 is provided with a cavity 110 . The box body 100 is made of light-shielding material to keep the inside of the cavity 110 dark. An inlet 111 and an outlet 112 are respectively provided on both sides of the box body 100 . Both the inlet 111 and the outlet 112 communicate with the cavity 110 .

As shown in FIG. 3 , FIG. 4 and FIG. 5 , the conveying device 200 is set according to a certain route, and is used to transport the product to be inspected into the cavity 110 , and output the product to be inspected from the cavity 110 after the inspection is completed. The conveying device 200 conveys the product 500 111 to be detected into the cavity 110 , and conveys the product 500 111 out of the cavity 110 through the outlet 112 .

The delivery device 200 includes a drive motor 210 and a plurality of drive shafts 220 . A plurality of driving shafts 220 constitute a conveying route of the product 500 to be inspected. Part of the drive shaft 220 is located inside the cavity 110 , and part of the drive shaft 220 is located outside the cavity 110 (not shown in the figure). In the present invention, a plurality of drive shafts 220 are arranged in a straight line. A plurality of conveying rollers 221 are sleeved on each driving shaft 220 . The transport roller 221 protrudes from the drive shaft 220 . The transport roller 221 rotates with the drive shaft 220 . The conveying roller 221 is made of flexible material, which can prevent the product from being scratched. Each drive shaft 220 is provided with a pulley 222 .

An adjustment substrate 230 is disposed below the driving shaft 220 . The adjustment substrate 230 is installed in the cavity 110 . The driving motor 210 is mounted on the adjustment substrate 230 . The drive motor 210 is provided with a drive pulley 211 . The drive belt 250 cooperates with the drive pulley 211 and the pulley 222 . The driving motor 210 drives a plurality of driving shafts 220 to rotate synchronously through the transmission belt 250 .

As shown in FIG. 3 and FIG. 6 , a positioning device is provided in the cavity 110 . The positioning device includes a first block 260 , a push block 270 and a second block 280 . The first block 260 is liftably arranged on the traveling route of the product 500 to be inspected. After the first block 260 rises, it protrudes beyond the product 500 to be detected and stops the product 500 to be detected from advancing, limiting the product 500 to be detected at this position; The first block 260 is connected with the piston rod of the first cylinder 261 . The first cylinder 260 drives the first block 260 up and down through the piston rod.

The push block 270 and the second block 280 are respectively movably arranged on both sides of the traveling route of the product 500 to be inspected. When one or both of the push block 270 and the second stopper 280 move toward each other, they can be used to push the product 500 to be inspected to move horizontally so that the product to be inspected 500 is located in a proper position. The number of pushing blocks 270 is three, and they are installed on the first positioning bracket 271 at intervals. The first positioning base frame 271 is connected with the piston rod of the third cylinder 273 . The third cylinder 273 is installed on the positioning plate 274 . The third cylinder 273 pushes the first positioning bracket 271 and the push block 270 to move horizontally through the piston rod. The adjustment substrate 230 is also provided with a first transmission device and a first guide device. The first transmission device includes a first screw rod 275 , and the first screw rod 275 is threadedly engaged with the positioning plate 274 . The first guiding device includes a first sliding block 276 and a first guide rail 277 . The first slider 276 is slidably mounted on the first guide rail 277 along the first guide rail 277 . The first guide rail 277 is mounted on the adjustment substrate 230 . The positioning plate 274 is installed on the first sliding block 276 . The driving force drives the first screw rod 275 to rotate to move the positioning plate 274 . When the positioning plate 274 moves, it can drive the third cylinder 273, the first positioning bracket 271 and the pushing block 270 to move. A first scale 281 parallel to the positioning plate 274 is disposed below the positioning plate 274 . The first scale 281 is used to measure the moving distance of the positioning plate 274 and the push block 270 , so as to control the positions of the push block 270 and the product 500 to be inspected more accurately.

There are three second stoppers 280 , which are set opposite to the three pushers 270 respectively. Three second stoppers 280 are disposed on the second positioning bracket 281 at intervals. The second air cylinder 282 is installed on the adjustment base plate 230 . The second positioning bracket 281 is connected with the piston rod of the second cylinder 282 . The second cylinder 282 drives the second positioning bracket 282 and the second stopper 280 to move horizontally through the piston rod.

A sensor 120 is disposed in the cavity 110 . The sensor 120 is disposed under the driving shaft 220 . When the product 300 to be inspected moves above the sensor 120 , the sensor 120 sends out a signal. According to the signal, the drive motor 240 can be controlled to slow down or stop working.

As shown in FIG. 3 and FIG. 7 , an irradiation device 300 is disposed in the cavity 110 . The illuminating device 300 includes a blue light source 330 . The blue light source 300 is used to emit monochromatic light to the product to be detected. The blue light source 300 is installed on the piston rod of the fourth cylinder 310 . The fourth cylinder 310 is installed on the inner wall of the box body 100 through the light source bracket 320 and is located above the drive shaft 220 so as to irradiate the product to be inspected from above the product to be inspected 500 . Through the fourth air cylinder 310 , the blue light source 330 is liftably disposed in the cavity 110 .

As shown in FIG. 3 , FIG. 8 , and FIG. 9 , two photographing devices 400 are installed in the cavity 110 . The photographing device includes a camera 401 . The camera 401 is arranged in the chamber 110 so as to be able to lift up and down and move horizontally, and is located above the product to be inspected. The camera 401 is set up and down through the vertical position adjustment device; it is set up to move horizontally through the horizontal position adjustment device. The up and down position adjusting device is used to adjust the up and down position of the camera. The horizontal position adjusting device is used for adjusting the horizontal position of the camera. The camera 401 is installed on the up and down moving block 410 ; a lower moving block 411 is arranged above the up and down moving block 410 . The upper end plate 412 is installed on the lower moving block 411 through the first guide shaft 413 . The up and down moving block 410 is movably sleeved on the first guide shaft 413 along the first guide shaft 413 . The up and down position adjusting device is the fourth screw rod 414 . The fourth threaded rod 414 is rotatably mounted on the upper end plate 412 , passes through the lower moving block 411 , and is screwed with the upper and lower moving block 411 . A first handle 431 is installed at the end of the fourth screw rod 414 . A first clamping member 434 is installed between the first handle 431 and the lower moving block 411 . A first locking screw 435 is mounted on the first clamping member 434 . By turning the first locking screw 435 , the clamping force of the first clamping member 434 on the fourth threaded rod 414 can be adjusted. By adjusting the first clamping member 434, the fourth threaded rod 414 can be locked so that it cannot rotate; it can also be released so that it can rotate. A second scale 441 is installed on the lower moving block 411 . Through the second scale 441, the moving distance of the up and down moving block 410 can be observed conveniently, and the moving distance can be controlled more precisely. The lower moving block 411 is movably sleeved on the second guide shaft 415 along the second guide shaft 415 . The end of the second guide shaft 415 is installed on the shaft seat 416 . A rotatable second threaded mandrel 417 is mounted on the shaft seat 416 . The second screw mandrel 417 is threadedly engaged with the lower moving block 411 . A second handle 432 is installed at the end of the second screw rod 417 . A second clip 436 is installed between the second handle 432 and the shaft seat 416 . A second locking screw 437 is installed on the second clamping member 436 . By turning the second locking screw 437 , the clamping force of the second clamping member 436 on the second threaded rod 417 can be adjusted. By adjusting the second clamping member 436, the second threaded rod 417 can be locked so that it cannot rotate; it can also be released so that it can rotate. An end plate 445 is installed at the end of the second guide shaft 415 . A third scale 442 is installed on the end plate 445 . The third scale 442 and the lower moving block 411 are arranged parallel to each other on one side of the lower moving block 411 . Through the third ruler 442, the moving distance of the lower moving block 411 can be observed conveniently, and its position can be controlled more precisely. The shaft seat 416 is installed on the second sliding block 418 . The second slider 418 is slidably mounted on the second guide rail 419 along the second guide rail 419 . The second guide rail 419 is installed on the base 420 . A rotatable third threaded mandrel 421 is installed on the base 420 . A transition plate 422 is mounted on the shaft seat 416 . The transition plate 422 is threadedly engaged with the third threaded rod 421 . The second sliding block 418 and the second guide rail 419 form a second guiding device, which is used to limit the moving track of the camera 410 when the camera 401 moves horizontally. The second screw rod 417 and the third screw rod 421 are horizontal position adjustment devices. The second screw rod 417 is perpendicular to the third screw rod 421 and can adjust the position of the camera 401 in two horizontal directions.

In the utility model, a monochromatic light source is firstly used to irradiate products with normal quality, and a camera is used to take pictures, and the photographed images are used as standard images. Then use a monochromatic light source to irradiate the product to be inspected, use a camera to take pictures, and compare the brightness of the image formed by the photo with the standard image brightness. If the brightness of the photographed image is the same as the standard image brightness or does not exceed the specified standard, then judge the product to be inspected The quality is normal.

The embodiments in the utility model are only used to illustrate the utility model, and do not constitute a limitation on the scope of the claims. Other substantially equivalent substitutions conceivable by those skilled in the art are all within the protection scope of the utility model.

Claims (25)

1. electronic product surface quality detection device, is characterized in that, comprises,

Casing, described casing is provided with cavity volume;

Light source, described light source is used for launching monochromatic light to product to be detected, and described light source is arranged in described cavity volume;

Camera, described camera is used for taking pictures to the product to be detected under light source irradiation;

Conveying device; Described conveying device is used for product to be detected to be delivered in described cavity volume, and exports in described cavity volume after detection;

Described product to be detected is delivered in the cavity volume of described casing by described conveying device, and described light source launches monochromatic light to described product to be detected; Described camera is taken pictures to the product to be detected under light source irradiation.

2. electronic product surface quality detection device according to claim 1, is characterized in that, described conveying device comprises CD-ROM drive motor, driving shaft; Described driving shaft number is multiple, forms the landline of product to be detected; The multiple driving shaft synchronous rotary of described drive motor.

3. electronic product surface quality detection device according to claim 2, is characterized in that, described driving shaft is set with conveying roller; Described conveying roller protrudes from described driving shaft; Described conveying roller rotates with described driving shaft.

4. electronic product surface quality detection device according to claim 2, is characterized in that, described CD-ROM drive motor drives described multiple driving shaft synchronous rotary by driving-belt; Described driving shaft is provided with belt pulley; Described driving-belt matches with described belt pulley.

5. electronic product surface quality detection device according to claim 2, is characterized in that, is also provided with the first block in described cavity volume; Described first block is arranged in the course of described product to be detected, and can arrange up or down; Described first block rising processus aboralis is for described product to be detected and stop that described product to be detected advances.

6. electronic product surface quality detection device according to claim 5, is characterized in that, is also provided with inductor in described cavity volume, and described inductor is arranged in described product course to be detected; When described product to be detected is delivered to assigned address, described inductor produces electric signal and carries described electric signal; When the described product to be detected of described inductor detection moves to assigned address, described first block rising processus aboralis, for described product to be detected, stops that described product to be detected advances.

7. electronic product surface quality detection device according to claim 6, is characterized in that, also comprises the first cylinder, the first block lifting described in described first air cylinder driven.

8. electronic product surface quality detection device according to claim 5, it is characterized in that, also be provided with pushing block in described cavity volume, described pushing block is arranged at described product course side to be detected movably, and described pushing block is arranged movably for promoting described Product Level to be detected.

9. electronic product surface quality detection device according to claim 8, is characterized in that, is also provided with the second block in described cavity volume, and described second block and described pushing block are arranged at described product course both sides to be detected respectively.

10. electronic product surface quality detection device according to claim 9, is characterized in that, also comprises the second cylinder; Described second block can be arranged with moving horizontally; Described in described second air cylinder driven, the second block moves horizontally.

11. electronic product surface quality detection devices according to claim 10, is characterized in that, described second block number is two or more, and interval is arranged; Described second block is installed on the second locating support; Described second locating support is connected with the piston rod of described second cylinder.

12. electronic product surface quality detection devices according to claim 8, is characterized in that, described pushing block can be arranged with moving horizontally, and promote described product to be detected and move when described pushing block moves horizontally.

13. electronic product surface quality detection devices according to claim 12, is characterized in that, also comprise the first scale, the first scale and described pushing block are arranged abreast.

14. electronic product surface quality detection devices according to claim 12, is characterized in that, also comprise the 3rd cylinder, and described in described 3rd air cylinder driven, pushing block moves horizontally.

15. electronic product surface quality detection devices according to claim 8, is characterized in that, also comprise the first gearing; Described pushing block is arranged on the first locating support; Driving force is moved by the first locating support described in described first actuator drives; Described first locating support drives described pushing block to move when moving.

16. electronic product surface quality detection devices according to claim 15, it is characterized in that, described first gearing comprises the first screw rod, described first screw rod is moved by the first locating support described in rotary actuation.

17. electronic product surface quality detection devices according to claim 15, is characterized in that, also comprise the first guide piece, described first guide piece comprises the first slide block and the first guide rail; Described first slide block can be installed on described first guide rail along described first slide; Described first locating support is installed on or is installed on one of described first slide block and described first guide rail by location-plate.

18. electronic product surface quality detection devices according to claim 1, is characterized in that, described light source is monochromatic source, and described light source is arranged at above described product mobile alignment to be detected.

19. electronic product surface quality detection devices according to claim 18, is characterized in that, described light source is blue-light source.

20. electronic product surface quality detection devices according to claim 18, it is characterized in that, described monochromatic source is liftably installed in described cavity volume.

21. electronic product surface quality detection devices according to claim 1, is characterized in that, described camera liftable also can be arranged at above described product to be detected with moving horizontally.

22. electronic product surface quality detection devices according to claim 21, it is characterized in that, also comprise in the second scale and the 3rd scale one or two, described second scale and the 3rd scale respectively with the lifting direction of described camera, move horizontally direction and arrange abreast.

23. electronic product surface quality detection devices according to claim 21, is characterized in that, also comprise upper-lower position adjusting gear and horizontal position adjustment device, and described upper-lower position adjusting gear is for adjusting the upper-lower position of described camera; Described horizontal position adjustment device is for adjusting the horizontal level of described camera.

24. electronic product surface quality detection devices according to claim 21, is characterized in that, also comprise the second guide piece, and described second guide piece is used at described camera lifting or the motion track moving horizontally camera described in limit.

25. electronic product surface quality detection devices according to claim 21, it is characterized in that, described camera is installed on vertical shift block; Bottom movable block is provided with above vertical shift block; Upper head plate is installed on the movable block of bottom by first axis of guide; Described vertical shift block can be sleeved on described first axis of guide along described first axis of guide movably; 4th screw mandrel is rotatably mounted on upper head plate, and through described bottom movable block, with described vertical shift block threaded engagement; Described bottom movable block can be sleeved on second axis of guide along second axis of guide movably; Second axis of guide end is installed on axle bed; Axle bed is provided with rotatable second screw mandrel, described second screw mandrel and bottom movable block threaded engagement; Described axle bed is installed on the second slide block, and described second slide block can be installed on described second guide rail along the second slide; Described second guide rails assembling is on base; Base is provided with rotatable 3rd screw mandrel, the 3rd screw mandrel and described second slide block threaded engagement.