TWI823173B

TWI823173B - Self-drilling screw

Info

Publication number: TWI823173B
Application number: TW110140675A
Authority: TW
Inventors: 顏辰叡; 沈嘉榮
Original assignee: 川巧螺絲工業股份有限公司
Priority date: 2021-11-02
Filing date: 2021-11-02
Publication date: 2023-11-21
Also published as: TW202319654A

Abstract

A self-drilling screw includes a head, a shank extending outwards from the head, a thread portion spirally disposed on the shank, and a drilling portion disposed on the shank and opposite to the head. The drilling portion has two symmetrical cutting grooves respectively extending from a tip of the drilling portion to the shank, a plurality of drilling bodies disposed between the cutting grooves, and a plurality of guiding grooves slantingly formed on the drilling bodies. Each drilling body has a first severing edge, a second severing edge, and a cutting edge formed between the first and second severing edges to thereby help increase the sharpness of the drilling body during cutting and improve the cutting and screwing effect. Chips caused during a cutting operation can be excluded outwards quickly through the cutting grooves and guiding grooves to thereby reduce the screwing resistance effectively.

Description

鑽尾螺絲Drill tail screw

本發明是有關於一種螺絲，特別是一種鑽尾螺絲。 The present invention relates to a screw, in particular to a drill tail screw.

參閱圖1，習知鑽尾螺絲1包含有一螺頭11，一由該螺頭11向外延伸之桿體12，複數螺旋環設於該桿體12上之螺牙13，一設於該桿體12上且相反該螺頭11一端之鑽尾14，以及二由該鑽尾14延伸至該桿體12之切削槽15；其中，該鑽尾14具有一由該桿體12向外延伸之鑽體141，一設於該鑽體141末端之鑽尖142，以及一形成於該鑽體141上且與該切削槽15相接處之刀鋒143；另，該二切削槽15係呈對稱且交錯環設由該鑽體141延伸至該桿體12上；是以，當該鑽尾螺絲1鎖合時，其切削物件過程中所產生之切屑，可直接排入該切削槽15內，且因該切削槽15係延伸至該桿體12上，故排入該切屑也可以順著該切削槽15排入該螺牙13上，使該切屑快速排出該物件外。 Referring to Figure 1, a conventional drill tail screw 1 includes a screw head 11, a rod body 12 extending outward from the screw head 11, a plurality of spiral rings provided on the threads 13 on the rod body 12, and a screw thread 13 on the rod body 12. There is a drill tail 14 on the body 12 opposite to one end of the screw head 11, and two cutting grooves 15 extending from the drill tail 14 to the rod body 12; wherein, the drill tail 14 has a drill tail 14 extending outward from the rod body 12. Drill body 141, a drill tip 142 provided at the end of the drill body 141, and a blade 143 formed on the drill body 141 and connected with the cutting groove 15; in addition, the two cutting grooves 15 are symmetrical and The staggered ring extends from the drill body 141 to the rod body 12; therefore, when the drill screw 1 is locked, the chips generated during the cutting of the object can be directly discharged into the cutting groove 15, and Since the cutting groove 15 extends to the rod body 12, the chips discharged can also be discharged into the thread 13 along the cutting groove 15, so that the chips can be quickly discharged out of the object.

然，實際使用後發現，該鑽尾14初始僅藉由該切削槽15進行排屑，其能產生的緩衝容屑效果有限，故在鎖設初期時所產生之大量切屑還是容易阻塞於該切削槽15內，造成鎖設阻力外，此外，該鑽尾14僅依靠該刀鋒143進行切削該物件，其切削的鋒利度有限，仍須改善。However, after actual use, it was found that the drill tail 14 only discharges chips through the cutting groove 15 at first, and the buffering and chip holding effect it can produce is limited. Therefore, a large amount of chips generated in the initial stage of locking is still easy to block the cutting. In addition to causing locking resistance in the groove 15, the drill tail 14 only relies on the blade edge 143 to cut the object, and its cutting sharpness is limited and needs to be improved.

因此，本發明之目的，是在提供一種鑽尾螺絲，其能有效提升鑽尾鋒利度及排屑效果，有效降低整體之鎖設阻力。Therefore, the purpose of the present invention is to provide a drill tail screw that can effectively improve the drill tail sharpness and chip removal effect, and effectively reduce the overall locking resistance.

於是，本發明鑽尾螺絲包含有螺頭，一由該螺頭向外延伸之桿體，一螺旋環設於該桿體上之螺牙，以及一設於該桿體上且相反該螺頭一端之鑽尾；其中，該鑽尾具有二對稱由該鑽尖延伸至該桿體之切削槽，分設於該二切削槽間之鑽體，以及分別傾斜開設於該鑽體上之導屑槽，而前述該每一鑽體上分別形成有一由該鑽尖往該桿體方向延伸之切削面，一連接該切削面之外緣面，一連接該外緣面至另一鑽體的切削面之排屑面，一凹設於該外緣面上且形成有該導屑槽之導屑面，一位於該鑽體末端且分別連接該切削面、外緣面、排屑面之錐面，一形成於該錐面與該切削面相接處之第一刀鋒，一形成於該切削面與外緣面之第二刀鋒，以及一形成於該第一刀鋒與第二刀鋒間之切刃；是以，透過該鑽體之第一刀鋒、第二刀鋒及切刃之設計下，能有效提升該鑽尾之鋒利度，增加切削能力與切削速度外，同時再搭配該切削槽及該導屑槽之設計下，該切削槽能提供足夠之容屑空間供該切屑容置緩衝外，其切屑也能經由該切削槽、導屑槽快速排出，有效降低鎖合阻力。Therefore, the drill tail screw of the present invention includes a screw head, a rod body extending outward from the screw head, a spiral ring provided on the screw thread on the rod body, and a screw head provided on the rod body and opposite to the screw head. A drill tail at one end; wherein, the drill tail has two symmetrical cutting grooves extending from the drill tip to the rod body, a drill body located between the two cutting grooves, and chip guides respectively provided at an angle on the drill body. groove, and each of the aforementioned drill bodies is respectively formed with a cutting surface extending from the drill tip to the direction of the rod body, one connecting the outer edge surface of the cutting surface, and one connecting the outer edge surface to the cutting surface of the other drill body. The chip discharge surface of the surface is a chip guide surface that is concave on the outer edge surface and forms the chip guide groove, and a tapered surface located at the end of the drill body and connecting the cutting surface, the outer edge surface, and the chip discharge surface respectively. , a first blade formed at the junction of the tapered surface and the cutting surface, a second blade formed between the cutting surface and the outer edge surface, and a cutting edge formed between the first blade and the second blade ; Therefore, through the design of the first blade, the second blade and the cutting edge of the drill body, the sharpness of the drill tail can be effectively improved, the cutting capacity and cutting speed are increased, and at the same time, the cutting groove and the guide Due to the design of the chip groove, the cutting groove can provide enough chip space for the chip to be accommodated and buffered. The chips can also be quickly discharged through the cutting groove and chip guide groove, effectively reducing the locking resistance.

有關本發明之前述及其他技術內容、特點與功效，在以下配合參考圖式之較佳實施例的詳細說明中，將可清楚的明白。The aforementioned and other technical contents, features and effects of the present invention will be clearly understood in the following detailed description of the preferred embodiments with reference to the drawings.

參閱圖2、圖3，本發明鑽尾螺絲3之第一較佳實施例，該鑽尾螺絲3包含有一螺頭31，一由該螺頭31向外延著一中心軸32a延伸之桿體32，一螺旋環設於該桿體32上之螺牙33，以及一設於該桿體32上且相反該螺頭31一端之鑽尾34；其中，該鑽尾34具有一形成於該鑽尾34末端之鑽尖341，二對稱由該鑽尖341延伸至該桿體32之切削槽342，分設於該二切削槽342間之鑽體343，以及分別傾斜開設於該鑽體343上之導屑槽344。Referring to Figures 2 and 3, the first preferred embodiment of the drill screw 3 of the present invention is shown. The drill screw 3 includes a screw head 31, and a rod 32 extending outwardly from the screw head 31 with a central axis 32a. , a spiral ring is provided on the thread 33 on the rod body 32, and a drill tail 34 is provided on the rod body 32 and opposite to one end of the screw head 31; wherein, the drill tail 34 has a drill tail 34 formed on the drill tail. The drill tip 341 at the end of 34 has two symmetrical cutting grooves 342 extending from the drill tip 341 to the rod body 32, a drill body 343 located between the two cutting grooves 342, and a drill body 343 respectively inclined and provided on the drill body 343. Chip guide 344.

仍續前述，該每一鑽體343具有一由該鑽尖341往該桿體32方向延伸之切削面3431，一連接該切削面3431之外緣面3432，一連接該外緣面3432至另一鑽體343的切削面3431之排屑面3433，一凹設於該外緣面3432上之導屑面3434，一位於該鑽體343末端且分別連接該切削面3431、外緣面3432、排屑面3433之錐面3435，一形成於該錐面3435與該切削面3431相接處之第一刀鋒3436，一形成於該切削面3431與外緣面3432之第二刀鋒3437，以及一形成於該第一刀鋒3436與第二刀鋒3437間之切刃3438，而前述該切削面3431於本實施例為平整狀設計，同時該切削槽342形成於該切削面3431與另一鑽體343的排屑面3433間，而該導屑面3434係傾斜凹設於該鑽體343上，而前述該導屑面3434與該外緣面3432之高低落差下而形成該導屑槽344，同時該導屑槽344一端係與該切削槽342連通。 Continuing with the above, each drill body 343 has a cutting surface 3431 extending from the drill tip 341 to the direction of the rod body 32, one connecting the outer edge surface 3432 of the cutting surface 3431, and one connecting the outer edge surface 3432 to the other side. A chip removal surface 3433 of the cutting surface 3431 of the drill body 343, a chip guide surface 3434 recessed on the outer edge surface 3432, and one located at the end of the drill body 343 and connected to the cutting surface 3431, outer edge surface 3432, respectively. The tapered surface 3435 of the chip removal surface 3433, a first blade 3436 formed at the junction of the tapered surface 3435 and the cutting surface 3431, a second blade 3437 formed at the cutting surface 3431 and the outer edge surface 3432, and a A cutting edge 3438 is formed between the first blade 3436 and the second blade 3437. The aforementioned cutting surface 3431 is designed to be flat in this embodiment, and the cutting groove 342 is formed between the cutting surface 3431 and the other drill body 343. The chip guide surface 3433 is between the chip guide surface 3433, and the chip guide surface 3434 is inclined and recessed on the drill body 343, and the chip guide groove 344 is formed by the height difference between the chip guide surface 3434 and the outer edge surface 3432. One end of the chip guide groove 344 is connected with the cutting groove 342 .

参閱圖4，本實施例使用時，係鎖設於一物件4上，其藉由該鑽尖341抵觸該物件4表面後，經由該螺頭31施予一下壓扭轉力道，透過該第一刀鋒3436逐漸對該物件4表面進行切削後，而於該物件4表面切削形成一周壁411之鎖合孔41，該第一刀鋒3436持續對該物件4進行切削，使該鑽尾螺絲3持續深入該物件4內，而該切刃3438及該第二刀鋒3437則可再對該周壁411再次進行切削，如此透過該第一刀鋒3436與該第二刀鋒3437及切刃3438設計下，將可增加該鑽尾螺絲3整體切削之鋒利度，同時切削該物件4過程中所產生之切屑(如圖中之箭頭)，可直接排入該切削槽342內，該切削槽342係由該切削面3431與該排屑面3433所圈圍，故能提供較大空間供該切屑排入與容置，且當該鑽尾螺絲3持續鎖入所產生之切屑，該切削槽342內之切屑除可直接順著該螺牙33排出外，同時也可以經由該導屑槽344快速排出，如此雙重排屑效果下，該切屑不易阻塞於該鎖合孔41內，能有效避免切屑阻塞而造成阻力，有效達到降低鎖合阻力及增進鎖合速度之功效。 Referring to Figure 4, when this embodiment is used, the fastening is provided on an object 4. After the drill tip 341 contacts the surface of the object 4, a pressing and twisting force is exerted through the screw head 31, and through the first After the blade 3436 gradually cuts the surface of the object 4, the locking hole 41 of the peripheral wall 411 is formed on the surface of the object 4. The first blade 3436 continues to cut the object 4, so that the drill screw 3 continues to penetrate deeply. In the object 4, the cutting edge 3438 and the second blade 3437 can cut the peripheral wall 411 again. In this way, through the design of the first blade 3436, the second blade 3437 and the cutting edge 3438, it will be possible to increase The overall cutting sharpness of the drill screw 3 and the chips (arrows in the figure) generated during the cutting of the object 4 can be directly discharged into the cutting groove 342, which is formed by the cutting surface 3431. Surrounded by the chip removal surface 3433, a larger space can be provided for the chips to be discharged and accommodated. When the drill screw 3 continues to lock the chips generated, the chips in the cutting groove 342 can be directly removed smoothly. The chips are discharged along the screw thread 33 and can also be quickly discharged through the chip guide groove 344. Under such a double chip discharge effect, the chips are not easily blocked in the locking hole 41, which can effectively avoid chip blockage and cause resistance, and effectively achieve Reduce locking resistance and increase locking speed.

參閱圖5、圖6，本發明第二較佳實施例，該鑽尾螺絲3仍包含有螺頭31、桿體32、螺牙33及鑽尾34等結構，而前述構件及欲達成之功效均與第一實施例相同，恕不詳述，特別是，本實施例中該桿體32上螺旋環設有二交錯設置之開槽35，且該開槽35經過處之螺牙33形成斷開型態，同時該每一開槽35環設之處經過一排屑面3433與該一導屑面3434，該每一開槽35分別與一導屑槽344及一切削槽342呈連通；另外，於本實施例中該切刃3438相反於該中心軸32a方向凸伸，使該切刃3438位於該鑽體343之最外側，且於本實施例中，該切刃3438可適時往旋鎖方向進行延伸，該切刃3438與該切削面3431不在同一平面上，使該切刃3438係凸伸於該切削面3431上。 Referring to Figures 5 and 6, a second preferred embodiment of the present invention is shown. The drill screw 3 still includes a screw head 31, a rod body 32, a screw thread 33, a drill tail 34 and other structures, and the aforementioned components have the effect to be achieved. They are the same as the first embodiment and will not be described in detail. In particular, in this embodiment, the spiral ring on the rod body 32 is provided with two staggered slots 35, and the threads 33 where the slots 35 pass form a break. Open type, at the same time, the surrounding area of each slot 35 passes through a chip discharge surface 3433 and a chip guide surface 3434, and each slot 35 is connected to a chip guide groove 344 and a cutting groove 342 respectively; In addition, in this embodiment, the cutting edge 3438 protrudes opposite to the direction of the central axis 32a, so that the cutting edge 3438 is located at the outermost side of the drill body 343, and in this embodiment, the cutting edge 3438 can be rotated in time. Extending in the locking direction, the cutting edge 3438 and the cutting surface 3431 are not on the same plane, so that the cutting edge 3438 protrudes on the cutting surface 3431.

參閱圖6、圖7，當該鑽尾螺絲3逐漸旋入一物件4時，且該切刃3438往旋鎖方向進行延伸，使該切刃3438與該切削面3431不在同一平面上，能使該切刃3438之銳利度增加，該第一刀鋒3436切削該物件4後，而於該物件4上形成一鎖合孔41，使該切刃3438位於該鑽尾34之最外側，而經過該切刃3438切削後所形成之周壁411，後續該第二刀鋒3437與該周壁411將產生一間隙，使該第二刀鋒3437不會直接接觸到該周壁411，能有效降低該第二刀鋒3437與該周壁411之阻力，同時切削後所產生之切屑(如圖中之箭頭)除可由該切削槽342、導屑槽344快速排出外，同時切屑也可以經由該切削槽342、導屑槽344排入該開槽35內，進而達到快速排屑之效果，因此使得該鑽尾螺絲3無論是旋鎖鋒利度、鎖合阻力及排屑功能均能達到良好之功效。Referring to Figures 6 and 7, when the drill screw 3 is gradually screwed into an object 4, and the cutting edge 3438 extends in the twisting direction, so that the cutting edge 3438 and the cutting surface 3431 are not on the same plane, so that The sharpness of the cutting edge 3438 is increased. After the first blade 3436 cuts the object 4, a locking hole 41 is formed on the object 4, so that the cutting edge 3438 is located at the outermost side of the drill tail 34 and passes through the drill tail 34. After cutting the peripheral wall 411 formed by the cutting edge 3438, a gap will be generated between the second blade edge 3437 and the peripheral wall 411, so that the second blade edge 3437 will not directly contact the peripheral wall 411, which can effectively reduce the distance between the second blade edge 3437 and the peripheral wall 411. In addition to the resistance of the peripheral wall 411, the chips (arrows in the figure) generated after cutting can be quickly discharged from the cutting groove 342 and the chip guide groove 344. At the same time, the chips can also be discharged through the cutting groove 342 and the chip guide groove 344. into the slot 35, thereby achieving the effect of rapid chip removal, so that the drill tail screw 3 can achieve good effects in terms of spin lock sharpness, locking resistance and chip removal function.

歸納前述，本發明鑽尾螺絲在於鑽尾具有二對稱由該鑽尖延伸至該桿體之切削槽，分設於該二切削槽間之鑽體，以及分別傾斜開設於該鑽體上之導屑槽；是以，透過該鑽體之第一刀鋒、第二刀鋒及該切刃之設計下，能提升有助於該鑽體切削時之鋒利度，且該切削槽與導屑槽提供足夠之容屑空間供該切屑容置緩衝外，其切屑也能經由該切削槽、導屑槽快速排出。To sum up the foregoing, the drill tail screw of the present invention is that the drill tail has two symmetrical cutting grooves extending from the drill tip to the rod body, a drill body provided between the two cutting grooves, and guides respectively inclined on the drill body. Chip flutes; therefore, through the design of the first blade, the second blade and the cutting edge of the drill body, the sharpness of the drill body during cutting can be improved, and the cutting flutes and chip guides provide sufficient In addition to the chip-containing space for containing and buffering the chips, the chips can also be quickly discharged through the cutting groove and chip guide groove.

惟以上所述者，僅為說明本發明之較佳實施例而已，當不能以此限定本發明實施之範圍，即大凡依本發明申請專利範圍及發明說明書內容所作之簡單的等效變化與修飾，皆應仍屬本發明專利涵蓋之範圍內。However, the above descriptions are only for illustrating the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, that is, simple equivalent changes and modifications may be made based on the patent scope of the present invention and the contents of the description of the invention. , should still fall within the scope covered by the patent of this invention.

[習知] 1:鑽尾螺絲 11:螺頭 12:桿體 13:螺牙 14:鑽尾 15:切削槽 141:鑽體 142:鑽尖 143:刀鋒 [創作] 3:鑽尾螺絲 31:螺頭 32:桿體 32 a:中心軸 33:螺牙 34:鑽尾 35:開槽 341:鑽尖 342:切削槽 343:鑽體 344:導屑槽 3431:切削面 3432:外緣面 3433:排屑面 3434:導屑面 3435:錐面 3436:第一刀鋒 3437:第二刀鋒 3438:切刃 4:物件 41:鎖合孔 411:周壁 [customary knowledge] 1: Drill tail screw 11:Screw head 12: Rod body 13: screw thread 14: drill tail 15: Cutting groove 141:Drill body 142:Drill tip 143:Blade [Creation] 3: Drill tail screw 31:Screw head 32: Rod body 32 a:Central axis 33: screw thread 34: drill tail 35: Grooving 341:Drill tip 342:Cutting groove 343:Drill body 344: Chip guide 3431:Cutting surface 3432:Outer edge surface 3433: Chip removal surface 3434: Chip guide surface 3435:Conical surface 3436:The First Blade 3437:Second Blade 3438:Cutting edge 4:Object 41: Locking hole 411: Surrounding wall

圖1是習知鑽尾螺絲之示意圖。圖2是本實施例第一較佳實施例之立體示意圖。圖3是本實施例第一較佳實施例之平面示意圖。圖4是本實施例第一較佳實施例之鎖合狀態示意圖。圖5是本實施例第二較佳實施例之立體示意圖。圖6是本實施例第二較佳實施例之平面示意圖。圖7是本實施例第二較佳實施例之鎖合狀態示意圖。 Figure 1 is a schematic diagram of a conventional drill tail screw. Figure 2 is a schematic three-dimensional view of the first preferred embodiment of this embodiment. Figure 3 is a schematic plan view of the first preferred embodiment of this embodiment. Figure 4 is a schematic diagram of the locking state of the first preferred embodiment of this embodiment. Figure 5 is a schematic three-dimensional view of the second preferred embodiment of this embodiment. Figure 6 is a schematic plan view of the second preferred embodiment of this embodiment. Figure 7 is a schematic diagram of the locking state of the second preferred embodiment of this embodiment.

3:鑽尾螺絲 3: Drill tail screw

31:螺頭 31:Screw head

32:桿體 32: Rod body

32a:中心軸 32a:Central axis

33:螺牙 33: screw thread

34:鑽尾 34: drill tail

341:鑽尖 341:Drill tip

342:切削槽 342:Cutting groove

343:鑽體 343:Drill body

344:導屑槽 344: Chip guide

3431:切削面 3431:Cutting surface

3432:外緣面 3432:Outer edge surface

3433:排屑面 3433: Chip removal surface

3434:導屑面 3434: Chip guide surface

3435:錐面 3435:Conical surface

3436:第一刀鋒 3436:The First Blade

3437:第二刀鋒 3437:Second Blade

3438:切刃 3438:Cutting edge

Claims

一種鑽尾螺絲，其包含有一螺頭，一由該螺頭向外延伸且形成有一中心軸之桿體，一螺旋環設於該桿體上之螺牙，以及一設於該桿體上且相反該螺頭一端之鑽尾；另，該鑽尾末端形成有一鑽尖，其特徵在於：該鑽尾具有二對稱由該鑽尖延伸至該桿體之切削槽，分設於該二切削槽間之鑽體，以及分別傾斜開設於該鑽體上之導屑槽；其中，該每一鑽體具有一由該鑽尖往該桿體方向延伸之切削面，一連接該切削面之外緣面，一連接該外緣面至另一鑽體的切削面之排屑面，一凹設於該外緣面上且形成有該導屑槽之導屑面，一位於該鑽體末端且分別連接該切削面、外緣面、排屑面之錐面，一形成於該錐面與該切削面相接處之第一刀鋒，一形成於該切削面與外緣面之第二刀鋒，以及一形成於該第一刀鋒與第二刀鋒間之切刃；另，該切削槽形成於該切削面與另一鑽體的排屑面間，且該切削槽與該導屑槽連通；再者，該桿體上螺旋環設有二交錯設置之開槽，且該開槽經過處之螺牙形成斷開型態，且該每一開槽環設之處經過至少一該排屑面與一該導屑面，該每一開槽分別與一導屑槽及一切削槽成連通。 A drill tail screw, which includes a screw head, a rod body extending outward from the screw head and forming a central axis, a spiral ring provided on the thread of the rod body, and a thread provided on the rod body and On the contrary, there is a drill tail at one end of the screw head; in addition, a drill tip is formed at the end of the drill tail, which is characterized in that: the drill tail has two symmetrical cutting grooves extending from the drill tip to the rod body, and are respectively provided in the two cutting grooves. The drill body between them, and chip guides respectively inclined on the drill body; wherein each drill body has a cutting surface extending from the drill tip to the direction of the rod body, and a cutting surface connected to the outer edge of the cutting surface surface, a chip removal surface connecting the outer edge surface to the cutting surface of another drill body, a chip guide surface recessed on the outer edge surface and forming the chip guide groove, and a chip guide surface located at the end of the drill body and respectively The tapered surface connecting the cutting surface, the outer edge surface and the chip discharge surface, a first blade formed at the junction of the tapered surface and the cutting surface, a second blade formed at the cutting surface and the outer edge surface, and A cutting edge formed between the first blade and the second blade; in addition, the cutting groove is formed between the cutting surface and the chip discharge surface of another drill body, and the cutting groove is connected with the chip guide groove; furthermore, the cutting groove is formed between the cutting surface and the chip discharge surface of another drill body, and the cutting groove is connected with the chip guide groove; , the spiral ring on the rod body is provided with two staggered slots, and the threads where the slots pass through form a broken pattern, and the place where each slot ring is located passes through at least one of the chip removal surfaces and a The chip guide surface and each groove are respectively connected with a chip guide groove and a cutting groove.

根據請求項1所述之鑽尾螺絲，其中，該切刃相反於該中心軸方向凸伸。 The drill tail screw according to claim 1, wherein the cutting edge is opposite to the The direction of the central axis protrudes.

根據請求項1或請求項2所述之鑽尾螺絲，其中，該每一切刃往旋鎖方向進行延伸。The drill tail screw according to claim 1 or claim 2, wherein each cutting edge extends in the twist-locking direction.